Impact of prosthetic material on mid- and long-term outcome of dental implants supporting single crowns and fixed partial dentures: A systematic review and meta-analysis

MENA Dental Science

24. January 2019

Samir Abou-Ayash, Malin Strasding, Gerta Rücker, Wael Att

Aim: The impact of prosthetic material selection on implant survival is not clear. The current criteria for choosing a prosthetic material seem to be based on clinician preferences. This systematic review aims to evaluate the impact of restorative materials on the mid- and long-term survival of implants supporting single crowns and fixed partial dentures.

Materials and methods: Hand and MEDLINE searches were performed to identify relevant literature for single crowns (SC) and fixed partial dentures (FPD). Further inclusion criteria were a mean follow-up period of at least 3 years, the inclusion of at least 10 patients in a relevant study cohort, and a clear description of prosthesis type and prosthetic material.

Results: A total of 63 studies for the SC group and 11 studies for the FPD group were included. Full arch restorations were not included. The materials utilised in the SC group were metal-ceramic (precious and non-precious), lithium-disilicate, veneered zirconia, veneered alumina, and nanoceramics. The materials used in the FPD group were metal-ceramic (precious), veneered titanium, metal-resin (precious), and veneered zirconia. No significant impact on the prosthetic material relating to mid- or long-term implant survival was identified. Furthermore, there were no statistically significant differences between the survival rates of the dental prostheses made from different materials (SC and FPD group). Single crowns made of nanoceramics showed a higher risk for decementation relative to other materials (0.80, 95% CI [0.67; 0.89]; P < 0.0001), whereas metal-resin FPDs showed a higher risk for chipping (0.36, 95% CI [0.23; 0.52]; P = 0.0072).

Conclusion: The current evidence suggests that prosthetic material selection has no influence on mid- and long-term survival of implants restored with single crowns and fixed partial dentures. Similarly, the prosthetic material seems to have no significant impact on prosthetic survival rates. Further research is required to provide more evidence regarding the impact of the prosthetic material on long-term outcome.

Introduction

The use of oral endosseous implants for the replacement of missing teeth has become a routine clinical procedure1. Today, oral implants are being used to treat various clinical situations, in particular partially and completely edentulous jaws. For implant-supported dental rehabilitations, several prosthetic solutions and materials are available2. In fact, clinicians have a wide variety of materials available for prosthetic solutions. With the progress of CAD/CAM techniques and improvements to the aesthetic characteristics of contemporary materials, new possibilities for both fixed and removable rehabilitations are continuously being introduced. For example, high-strength ceramics can be used today as a framework material for veneered restorations, as well as for a final monolithic restoration. With such a wide spectrum of available materials and restorative options, clinicians are often confused about selecting the ideal prosthetic material, which facilitates ideal aesthetics, biocompatibility, and long-term stability. Apparently, material selection for the definitive prosthesis seems to depend not only on mechanical properties and anatomic and patient-related factors, but also on a clinician’s individual preferences3.

The influence of many factors on the long-term outcome and on technical or biological complication rates of implant-borne fixed partial dentures (FPDs) is well described in scientific literature. For example, retention mechanisms seem to have an influence on technical and biological complication rates4,5. On the one hand, screw-retained single crowns and fixed partial dentures seem to have a higher risk for technical complications than cement-retained single crowns or fixed partial prostheses. On the other hand, when all fixed restorations (regardless of the restoration type) are compared, significantly fewer complications were observed with screw retention4. This demonstrates that factors such as the retention mechanism can have different effects on various restoration types.

Another potential factor influencing the long term-outcome in partially edentulous patients is the length of the utilised implants. A recently published systematic review comparing short vs standard-length implants found that there were no significant differences in marginal bone loss, complication, or prosthesis failure rates. However, implants with lengths of less than 8 mm presented a higher risk of implant failure6. Another 5-year follow-up of a randomised controlled trial showed similar survival and success rates, and no statistically significant complication rates in partially edentulous cases, when 6 mm implants were compared with 10 mm implants7.

There appear to be several factors influencing the long-term survival and success rates of implant-borne dental restorations, including, but not necessarily limited to, restoration type, retention mechanism, and implant length. For example, the choice of the prosthetic material is an additional factor to be considered in combination with the aforementioned variables, as it might play a role in determining long-term outcome8.

While many studies have reported on implants and factors affecting their survival, little knowledge is available about the impact of the prosthetic material. For example, it is not clear whether an all-ceramic crown would lead to an improved outcome for the implant relative to a metal-ceramic crown. Also, the influence of the restorative material on the clinical outcome of the implant-borne prosthetic rehabilitation is unclear. So far, studies addressing the outcome of implant rehabilitations made of different materials primarily compared two materials. Moreover, varying study designs make it difficult to assess the outcome and impact of a specific material. An evaluation of the impact of the prosthetic material on implant survival would enhance clinical knowledge and provide clinicians with guidelines regarding material selection.

Therefore, the aim of this systematic literature review and meta-analysis is to examine whether a correlation exists between the type of restorative material and the clinical outcome of implants, as well as the associated prosthetic rehabilitations.

Materials and methods

Study protocol

The study protocol was set in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement9. The focused leading question was set according to the PICO model for clinical questions. This model aids the discovery of clinically relevant evidence in literature by dividing the leading question into four subcategories (population, intervention, comparison, and outcome). The four criteria for this study were as follows:

Population: Partially edentulous patients receiving fixed implant-supported restorations;

Intervention: Prosthodontic rehabilitation by means of implant-supported single crowns (SCs) or fixed partial dentures (FPDs);

Comparison: Performance of various prosthetic materials used for each type of restoration;

Outcome: Implant and prosthetic survival, as well as technical complications related to the restorative material and the type of prosthesis.

 

After analysing the different points of this model, the resulting PICO question was: “Does the choice of restorative material influence the mid- and long-term outcome of implants and/or fixed partial dentures?”

Definitions

Prior to the systematic search, several terms were defined: “Implant survival” was defined as implants that were still in situ at the point of observation. Implant conditions such as surrounding bone, soft tissue, or signs of inflammation were not parameters considered in the evaluation of survival. “Prosthetic survival” was defined as prostheses that were still in situ, even if repairs of any kind were necessary (e.g. renewal of the veneering material). “Technical complications” were subdivided into four distinct categories: abutment fracture, chipping, screw loosening, and decementation of the superstructure.

Inclusion and exclusion criteria

For the systematic literature search, the following inclusion and exclusion criteria were compiled:

Inclusion criteria

Human clinical studies (randomised controlled trials, controlled trials, prospective studies, retrospective studies, case series);

Fixed implant-supported prostheses and single crowns;

Titanium implants;

Partially edentulous patients;

Documentation of prosthetic material;

Documentation of restoration type;

Number of patients/ study arm or cohort ≥ 10;

Mean follow-up period ≥ 3 years;

Publication in English.

Exclusion criteria

In vitro or animal studies;

Removable partial denture;

Ceramic implants;

Edentulous patients;

Insufficient documentation of prosthetic material;

No documentation of restoration type;

Fewer than 10 patients in relevant study arm/cohort;

Mean follow-up period less than 3 years;

Publications not written in English;

Combined tooth-implant-supported restorations;

Search strategy and study selection

For the initial electronic search in the MEDLINE library (via PubMed), the types of dental restorations were divided into two different groups: single crowns (SC group) and fixed partial dentures (FPD group). For each group, a separate initial search of literature without any filters was performed using distinct key words (Table 1). Furthermore, reference lists of review articles with similar topics were systematically screened, and potentially relevant articles were added to the results of the electronic search. After elimination of duplicates, the titles of the remaining articles were checked for adequacy, according to the inclusion criteria. Irrelevant titles (e.g. in vitro studies) were excluded. When the relevance of studies was uncertain according to the title, the studies were included for abstract screening. When the relevance of the studies remained unclear after reading the abstract, they were included for full text screening, resulting in a selection of possibly eligible full texts. After reviewing the full texts, irrelevant articles were excluded, and data of the remaining articles was extracted whenever possible. Study selection and data extraction were performed for each group independently by two reviewers (SA and MS). Afterwards, every disagreement regarding the inclusion of specific articles was solved by discussion. Tables 2a and 2b illustrate the study selection process for each group. For data extraction, identical study forms for each group were designed, including the following parameters: authors, title, year of publication, study design, study period, number of patients, number of implants in the study, implant system, implant lengths, implant diameters, implant material, abutment material, timing of implant placement, loading protocol, number of implants per prosthesis, number of prostheses in total, jaw, number of cantilevers, length of cantilever, type of retention, bone augmentation, soft tissue augmentation, CAD/CAM workflow, mean radiographic bone loss, implant loss before loading, prosthetic survival rate, screw loosening, decementation, chipping, prosthesis fracture, framework fracture, abutment fracture, peri-implantitis, mucositis, implant fracture, and superstructure material.

Table 1 Key words for initial database search.

Group Search Terms Initial hits
SC (“crown” OR “crowns” OR “partially edentulous” OR “single Crown” OR “single Crowns”) AND (“implant” OR “implants” OR “dental implant” OR “dental implants”) 3411
FPD (“fixed partial prostheses” OR “fixed partial prosthesis” OR “partially edentulous” OR “implant bridge”) AND (“implant” OR “implants” OR “dental implants“) 1147

Risk of bias within the studies

For quality assessment, six quality categories were implemented to evaluate the included studies10: “fair” for retrospective studies, “average” for prospective case studies, “good” for prospective studies with historical control, “better” for prospective studies with concurrent controls, “best” for double-blind randomised controlled trials, and “unknown” for studies not fitting one of the other five criteria. Due to the high degree of heterogeneity observed in study design and in results of the different studies that were considered, a decision was made to include all studies that were rated at least “fair”.

Risk of bias across the studies

In most of the studies, primary outcomes differed from our leading question. The choice of prosthetic material was often considered as a marginal note. Therefore, a potential risk of bias might be introduced via extracting and evaluating data from studies that do not refer to the influence of the prosthetic material.

Statistical analysis

For evidence synthesis using meta-analysis, the open source statistical environment R (version 3.2.0)11 with the R packages “meta”12 and “metafor”13 was used. The random effects model was used throughout. The outcomes were the proportion of surviving implants, the prosthetic survival proportion, the proportion of screw-loosening events by number of implants, the proportion of abutment fractures by the number of implants, the proportion of chipping by the number of prostheses, and the proportion of decementation by the number of prostheses. Proportions were pooled using the logit transformation. In addition, loss of implants was measured as an incidence rate per average follow-up time. For all outcomes, the impact of material was analysed using meta-regression13. The generally poor reporting in the primary studies made it impossible to adjust for potential intrasubject correlation due to the varying unit of analysis (patients, implants, prostheses).

Synthesis of results

Most of the included studies did not compare multiple restorative materials directly, but described, for example, different augmentation techniques.

Data were extracted whenever the restorative material was mentioned and the study met the inclusion criteria. For simplification, not all of the columns of the study form had to be completed, if certain information was not provided in a given study (e.g. implant lengths). Whenever implant or prosthetic survival rates were not reported, studies were not included for data extraction, but taken into consideration for strengthening or weakening results of the meta-analysis. If multiple study arms or cohorts were identified in the same study, data from each group was recorded separately. This resulted in a higher number of study populations than indicated by the number of included studies.

The primary outcome of the meta-analysis was to evaluate the implant and prosthetic survival rates as functions of the restorative material and restoration type. Therefore, restorations were divided into metal-based and all-ceramic restorations, and secondly, whenever possible, divided into groups according to the exact restoration material (e.g. glass ceramics or ceramic-veneered precious alloy). Hence, several studies did not describe the exact restoration material, but only whether an all-ceramic or metal-based restoration was used, such that the number of included studies was higher for the comparison between metal-based and all-ceramic materials than for the comparison of the exact materials used.

Furthermore, to be able to compare the results of the included studies, despite the variable follow-up periods, the implant loss rate per 10 implant years was calculated. This rate describes the risk of an implant loss regarding one single implant for a period of 10 years, or the risk of an implant loss of two implants over 5 years. Additionally, the incidence rates for screw loosening, decementation of superstructures, chipping, and abutment fractures were calculated.

Results

Literature search

As previously described, an initial literature search via MEDLINE and a manual search were performed for each group separately (Table 1). 3411 studies were included for the SC group, while 1147 studies were included for FPDs. After title-, abstract-, and full text screening, 83 studies remained in the SC group, and 18 remained in the FPD group for data extraction. During data extraction, 21 further studies from the SC group and seven from the FPD group were excluded, resulting in a final number of included studies of 62 for the SC group and 11 for the FPD group (Tables 2a and 2b). Reasons for exclusion during data extraction are listed in Tables 3a and 3b. The results for the two groups are henceforth described separately.

Tables 2a and 2b Study selection process for single crowns (SCs) and fixed partial dentures (FPDs).

Authors Type of study Quality assessment
Balshi TJ et al.42 Prospective good
Berberi AN et al.43 Prospective good
Bilhan H et al.44 Retrospective fair
Bonde MJ et al.45 Retrospective fair
Buser D et al.46 Prospective good
Calandriello R & Tomatis M47 Prospective good
Cannizzaro G et al.48 RCT best
Cannizzaro G et al.49 RCT best
De Bruyn H et al.50 Prospective better
Cosyn J et al.51 Prospective good
Covani U et al.52 Prospective good
Covani U et al.53 Prospective good
Davis DM54 Prospective good
Donati M et al.55 Prospective good
Enkling N et al.56 RCT best
Fenner N et al.57 Prospective better
Glauser R et al.58 Prospective good
Gotfredsen K et al.59 Prospective better
Guarnieri R et al.60 Prospective good
Ioannidis A et al.61 RCT best
Jemt T62 Retrospective fair
Jemt T & Pettersson P63 Retrospective fair
Khraisat A et al.64 Prospective good
Kolgeci L et al.65 Prospective good
Lai HC et al.66 Retrospective fair
Lang LA et al.67 Prospective good
Lops D et al.68 Prospective better
Mangano C et al.69 Retrospective fair
Mangano FG et al.70 Prospective good
Authors Type of study Quality assessment
Mangano FG et al.71 Retrospective fair
Mericske-Stern R et al.72 Retrospective fair
Montoya-Salazar V. et al.73 RCT best
Nejatidanesh et al.74 Retrospective fair
Palmer RM75 Prospective good
Perelli M. et al.76 Prospective good
Pieri F et al.77 Prospective better
Proussaefs P & Lozada J78 Prospective good
Rinke S et al.79 Retrospective fair
Rinke S et al.80 Retrospective fair
Roccuzzo M et al.81 Prospective good
Romanos GE et al.82 RCT best
Romeo E et al.83 Prospective good
Rossi F et al.84 Prospective good
Rossi F et al.85 RCT best
Schepke U86 Prospective good
Schropp L et al.87 RCT best
Schropp L et al.88 RCT best
Sorrentino R et al.89 Retrospective fair
Turkyilmaz I et al.90 Prospective better
Vanioglu AB et al.91 Prospective better
Vigolo P et al.92 Prospective better
Visser A et al.93 Prospective good
Weber HP et al.94 Prospective good
Worni A et al.95 Prospective good
Zarone F et al.96 Prospective good
Zembic A et al.97 RCT best
Zembic A et al.98 Prospective good
Zhao X et al.99 Retrospective fair

Table 3a Reasons for study exclusion (SC group).

Study Reason for exclusion
Bergenblock et al. 201214 Pooled results
Bianchi et al. 200415 Pooled results
Branzen et al. 201516 Pooled results
Dierens et al. 201617 Pooled results
Ekfeldt et al. 201118 Pooled results
Grassi et al. 201519 Zirconia implants
Hälg et al. 200820 Pooled results
Hosseini et al. 201321 Pooled results
Lops et al 201222 Pooled results
Mangano et al. 201023 Pooled results
Mangano et al. 201524 Pooled results
Moberg et al. 199925 Pooled results
Özkan et al. 201126 Pooled results
Özkan et al. 200727 Pooled results
Passos et al. 201628 Pooled results
Spies et al. 201529 Zirconia implants
Spies et al. 201530 Zirconia implants
Tartaglia et al. 201531 Pooled results
Thoma DS et al. 201532 Different target variables
Vigolo et al. 200033 Pooled results
Walton 201534 Pooled results

Table 3b Reasons for study exclusion (FPD-group).

Study Reason for exclusion
Astrand et al. 200435 No implant/ prosthetic survival rates reported
Becktor et al. 200736 No implant/ prosthetic survival rates reported
Bornstein et al 201037 Pooled results
Felice et al. 201438 No implant/ prosthetic survival rates reported
Maló P et al 201339 Pooled results
Nissan J et al. 201140 Unclear statistics
Ortorp A et al. 199941 Pooled results

Study characteristics

Most of the included studies were prospective studies, but RCTs, retrospective studies and case series were also included. The type of study and quality assessment of each study is shown in Tables 4a and 4b. The majority of the studies had an observation period between 3 and 10 years. Studies with longer observation periods were scarce. In the SC group, 76 study populations across 62 studies and in the FPD group, 15 populations across 11 studies were investigated. Various implant types with different surface modifications were placed in these studies. Several types of prosthetic materials were used in the studies (all types of metal-ceramic, metal-resin and all-ceramic materials). Screw-retained, as well as cemented restorations were analysed. Differences in time of implant placement, loading protocols, augmentation procedures, number of implants per prosthesis, abutment materials, implant lengths, implant diameters, number of cantilevers, and lengths of cantilevers were not taken into consideration for the meta-analysis.

Table 4b  Quality assessment of included studies (FPD-group).

Authors Type of study Quality assessment
Barnea E et al.100 Retrospective fair
Brägger U et al.101 Prospective good
Francetti L et al.102 Prospective good
Göthberg C et al.103 RCT best
Jemt T et al.104 Retrospective fair
Kreissl ME et al.105 Prospective good
Mangano F et al.106 Prospective good
Pozzi A et al.107 Prospective better
Romeo E et al.108 Prospective good
Romeo E et al.109 Prospective good
Romeo E et al.7 RCT best

Single crowns

All-ceramic vs metal-based SCs

For the analysis of implant survival, the results of 24 study cohorts of the all-ceramic group and 53 of the metal-based group were used for the meta-analysis (Tables 5 and 6). The implant survival rate in the all-ceramic group (included studies n = 23) was 0.97 (95% CI [0.95; 0.98]) with a mean observation period of 5.4 years, and 0.96 (95% CI [0.95; 0.97]) among metal-based SCs with a mean observation period of 5.6 years. This difference was not statistically significant (P = 0.1724). The meta-regression-analysis showed no impact on the different observation periods for the two groups (P = 0.5976). The calculated implant loss rate per 10 implant years was 0.06 (95% CI [0.04; 0.08]) for the all-ceramic and 0.07 (95% CI [0.05; 0.10]) for the metal-based group. This difference was not statistically significant (P = 0.3737).

Prosthetic survival rates were 0.95 (95% CI [0.94; 0.97]) in the all-ceramic (included studies n =19) and 0.97 (95% CI [0.96; 0.98] in the metal-based group (n = 27). The difference was not significant (P = 0.0872). Subgroup analyses for the incidence rates of screw loosening, decementation, abutment fractures and chipping revealed no statistical differences between the two groups.

Table 5  Included studies in the all-ceramic single crown group.

Study Study period (years) Patients (n) Implants (n) Prostheses (n) Superstructure material Abutment material Implant survival (%) Prosthetic survival (%) Abutment fracture (%) Chipping (%) Screw loosenig (%) Decementation (%)
Berberi AN et al.43 3 20 20 20 Veneered Zirconia Ti 100
Bonde MJ et al.45 10 42 46 46 All ceramic (non defined) Ti 93.5 93.5
Buser D et al.46 3 20 20 20 Veneered Zirconia Ti 100 100
Calandriello R & Tomatis M47 5 33 40 40 Veneered Alumina Ti 95 100 0 0 0 0
De Bruyn H et al.50 5 55 55 55 Veneered Alumina Ti 94.6
De Bruyn H et al.50 5 58 58 58 Veneered Alumina Ti 98.3
Fenner N et al.57 7.2 13 13 13 All ceramic (non defined) Al 100 100 0 0 0 0
Glauser R et al.58 4.1 18 36 36 Glass ceramics Zr 100 97.2 0 8.3 5.6 0
Guarnieri R et al.60 5 21 21 21 All ceramic (non defined) Zr 95.2 0 0 0 4.8
Jemt T62 10 15 18 18 All ceramic (non defined) Ti 100 0 0 16.7 0
Kolgeci L et al.65 3.3 67 120 120 Veneered Zirconia Zr 98.3 95.8 0
Lops D et al.68 5 37 37 37 Veneered Zirconia Zr 100 100 0 10.8 2.7 0
Nejatidanesh et al.74 4.9 122 232 232 Veneered Zirconia Ti 99.2 97.5 1.6
Pieri F et al.77 5 29 29 29 Veneered Zirconia Ti/Zr 100 100 0 7 0 3.5
Rinke S et al.79 6.5 27 42 42 Veneered Zirconia Zr 100 97.6 2,3 11.9 4.7 9.5
Schepke U et al.86 1.1 50 50 Nano Ceramic Zr 100 94 80
Sorrentino R et al.89 6 48 81 81 Veneered Alumina Ti/Al 97.6 95.1 0.9 0 0
Vanioglu AB et al.91 5 6 11 11 Glass ceramics Zr 100 100 0 0 9.1 0
Vanioglu AB et al.91 5 6 12 12 Glass ceramics Ti 100 100 0 0 0 0
Visser A et al.93 5 93 92 92 Veneered Zirconia Ti 96.7 88 0 1.1 2.2 0
Worni A et al.95 5 70 70 Veneered Zirconia Zr 98.6 94.2
Zarone F et al.96 4 58 58 Veneered Alumina Al/Ti 100 98.3
Zembic A et al.97 5.6 18 18 18 All ceramic (non defined) Zr 88.9 100 0 0 0 0
Zembic A et al.98 11.3 16 23 23 Glass ceramics Zr 100 100 9.7 6.5

Table 6  Included studies in the metal-ceramic single crown group.

Study Study period (years) Patients (n) Implants (n) Prostheses (n) Superstructure material Abutment material Implant survival (%) Prosthetic survival (%) Abutment fracture (%) Chipping (%) Screw loosenig (%) Decementation (%)
Balshi TJ et al.42 5.5 140 164 164 Metal-Ceramic (precious) - 95.7
Bilhan H et al.44 3 80 122 122 Metal-Ceramic (non-defined) - 91.8
Cannizzaro G et al.48 4 30 29 29 Metal-Ceramic (non-defined) - 96.7
Cannizzaro G et al.48 4 30 31 31 Metal-Ceramic (non-defined) - 96.8
Cannizzaro G et al.48 4 30 29 29 Metal-Ceramic (non defined) - 96,7
Cannizzaro G et al.49 3 20 52 52 Metal-Ceramic (non-defined) - 100 100 0 3.8 1.9 0
Cannizzaro G et al.49 3 20 56 56 Metal-Ceramic (non-defined) - 100 100 0 3.6 0 0
Cosyn J et al.51 3 25 25 25 Metal-Ceramic (non-defined) - 96 100 0 0 0 4
Covani U et al.52 10 91 159 159 Metal-Ceramic (non-defined) - 91.8 100 0 1.3 5.7 0
Covani U et al.53 5 47 47 47 Metal-Ceramic (non-defined) Ti 95.7
Davis DM54 5 20 23 23 Metal-Ceramic (non-defined) - 87 13 18.2 52.2
Donati M et al.55 12 31 35 35 Metal-Ceramic (non-defined) Ti 90.9 0 5.7 11.4
Enkling N et al.56 3 25 25 25 Metal-Ceramic (non-defined) Ti 100
Enkling N et al.56 3 25 25 25 Metal-Ceramic (non-defined) Ti 100
Fenner N et al.57 7.2 15 15 15 Metal-Ceramic (non-defined) Ti 100 100 0 13.3 0 0
Gotfredsen K et al.59 10 10 10 10 Metal-Ceramic (non-defined) Ti 100 90 15 10 10
Gotfredsen K et al.59 10 10 10 10 Metal-Ceramic (non-defined) Ti 100 90 15 10 10
Ioannidis A et al.61 3 15 15 15 Metal-Ceramic (non-defined) - 100 0 5.9 5.9 0
Ioannidis A et al.61 3 17 17 17 Metal-Ceramic (non-defined) - 100 0 5.9 0 0
Jemt & Pettersson 63 3 49 69 69 Metal-Ceramic (non-defined) - 98.5 44.9
Jemt T 62 10 13 15 15 Metal-Ceramic (non-defined) Ti 100 100 0 0 20 0
Khraisat A et al. 64 3 12 12 12 Metal-Ceramic (non-defined) - 100
Khraisat A et al. 64 3 12 12 12 Metal-Ceramic (non-defined) - 100
Lai HC et al.66 10 168 231 231 Metal-Ceramic (non-defined) - 98.3 95.2 0.4 2.6 5.6 3.9
Lang LA et al.67 5 10 10 10 Metal-Ceramic (non-defined) - 100
Lops D et al.68 5 44 44 44 Metal-Ceramic (non-defined) Ti 100 100 0 6.8 2.3 0
Mangano C et al.69 3 20 20 20 Metal-Ceramic (non-defined) - 100 100
Mangano FG et al.70 5.6 191 212 212 Metal-Ceramic (non-defined) - 98.5 100 0 0.9 0.5 0
Mangano FG et al.71 10 482 482 Metal-Ceramic (non-defined) - 99.2 99.2 0 0 0.6 20
Mericske-Stern R et al.72 4.3 72 109 109 Metal-Ceramic (precious) Ti 97.3 95.8 4.2 1.4 26.4 1.4
Montoya-Salazar V. et al.73 3 18 18 18 Metal-Ceramic (non-precious) Ti 94.4
Montoya-Salazar V. et al.73 3 18 18 18 Metal-Ceramic (non-precious) Ti 100
Palmer RM 75 5 14 14 14 Metal-Ceramic (non-defined) - 100 100 0 7.1 0 7.1
Perelli M. et al. 76 5 87 110 110 Metal-Ceramic (non-defined) - 90 93.1 0 0.9 1.8
Proussaefs P & Lozada J 78 3 10 10 10 Metal-Ceramic (non-defined) - 100 100
Rinke S et al.80 6.8 65 112 112 Metal-Ceramic (precious) - 100 97.3 0 8.9 3.6 14.3
Roccuzzo M et al.81 10 30 36 36 Metal-Ceramic (precious) - 100
Romanos GE et al.82 12.1 10 36 36 Metal-Ceramic (non-defined) - 100 100
Romanos GE et al.82 12.4 10 36 36 Metal-Ceramic (non-defined) - 100 100
Romeo E et al. 83 7 103 176 176 Metal-Ceramic (precious) - 96.8
Rossi F et al.84 5 45 60 60 Metal-Ceramic (precious) Ti 86.7
Rossi F et al.84 5 45 60 60 Metal-Ceramic (precious) Ti 96.7
Rossi F et al.85 5 35 40 40 Metal-Ceramic (non-defined) Ti 95
Schropp L et al. 87 5 18 18 18 Metal-Ceramic (non-defined) - 88.9 88.9 0 0 0
Schropp L et al. 87 5 16 16 16 Metal-Ceramic (non-defined) - 93.7 93.7 0 0 0
Schropp L et al. 88 10 18 18 18 Metal-Ceramic (non-defined) - 90.9
Schropp L et al. 88 10 40 37 37 Metal-Ceramic (non-defined) - 97.6
Turkyilmaz I et al. 90 4 29 34 34 Metal-Ceramic (precious) Ti 94.4
Turkyilmaz I et al. 90 4 10 23 23 Metal-Ceramic (precious) Ti 95.7
Vigolo P et al.92 4 20 40 40 Metal-Ceramic (precious) Au/Ti 100 100 0 0 0 0
Weber HP et al. 94 3 152 152 Metal-Ceramic (non-defined) - 100 100 0 0 0 0
Zembic A et al. 97 5.6 18 10 10 Metal-Ceramic (non-defined) Ti 90 100 0 30 0 0
Zhao X et al.99 6.2 45 45 45 Metal-Ceramic (precious) Ti 100 100 0 4.4 0 0

Exact restorative materials

For the meta-analysis of implant survival rates, the results of two study cohorts of veneered non-precious alloys, 11 of veneered precious alloys, 10 of veneered zirconia, five of veneered alumina, four of glass ceramics, and one for nanoceramics, were included. The veneering material was ceramic. For the analysis of the prosthetic survival rates, three study cohorts of veneered precious alloys, 12 of veneered zirconia, four of veneered alumina, four of glass ceramics, and one of nanoceramics, were included. For veneered non-precious alloys, no details regarding prosthetic survival rates could be found. Implant and prosthetic survival rates, as well as the 95% CI, can be seen in Table 7. The differences in implant and prosthetic survival rates were not statistically significant (implant survival: P = 0.4061; prosthetic survival: P = 0.8580). The meta-regression-analysis showed no impact of the different observation periods on the comparison between any of the groups (implant survival: P = 0.2120; prosthetic survival: P = 0.9622). The calculated implant loss rate per 10 implant years showed no statistically significant differences among all groups (P = 0.6502).

Subgroup analyses for the prosthetic complication rates showed no statistically significant differences for screw loosening, abutment fractures, or chipping between any of the groups. The incidence rate for decementation was significantly higher for the nanoceramic group relative to all of the other groups (P < 0.0001). Incidence rates and 95% CI can be seen in Table 7.

Table 7  Results for exact restorative materials (SC group).

Material Number of studies included Implant survival rates + 95% CI Implant loss per 10 implant years Number of studies included Prosthetic survival rates + 95% CI Decementation + 95% CI
Veneered metal-ceramics (non-precious) 2 0.96 [0.81; 0.99] 0.15 [0.03; 0.73] - - -
Veneered metal-ceramics (precious) 11 0.96 [0.93; 0.98] 0.07 [0.04; 0.13] 4 0.97 [0.94; 0.98] 0.03 [0.01; 0.15]
Veneered zirconia 10 0.98 [0.97; 0.99] 0.04 [0.02; 0.07] 9 0.96 [0.93; 0.97] 0.04 [0.02; 0.09]
Veneered alumina 5 0.97 [0.93; 0.98] 0.07 [0.03; 0.13] 3 0.96 [0.92; 0.98] 0.01 [0.00; 0.06]
Glass ceramics 4 0.97 [0.87; 0.99] 0.06 [0.01; 0.31] 4 0.97 [0.91; 0.99] 0.03 [0.01; 0.13]
Nano Ceramics 1 0.99 [0.86; 1.00] 0.09 [0.01; 1.45] 1 0.94 [0.83; 0.98] 0.80 [0.67; 0.89]

Fixed Partial Dentures

All-ceramic vs metal-based FPDs

For the analysis of implant survival, the results from one study cohort of the all-ceramic group, two of the metal-based FPDs with resin facings, and eight of metal-based FPDs veneered with ceramics were included in the meta-analysis (Table 8). The survival rate of the all-ceramic group was 0.96 (95% CI [0.89; 0.99]) with a mean observation time of 3 years, 0.97 (95% CI [0.94; 0.99]) in the group of the metal-based FPDs with resin facings with a mean observation time of 5 years, and 0.96 (95% CI [0.94; 0.98]) in the ceramic-veneered group with a mean observation period of 5.9 years. The differences were not statistically significant (P = 0.835). The calculated implant loss rate per 10 implant years was 0.12 (95% CI [0.04; 0.38]) for the all-ceramic, 0.05 (95% CI [0.03; 0.11]) for the metal-based group with resin facings, and 0.06 (95% CI [0.03; 0.15]) for the ceramic-veneered group. The differences were not statistically significant (P = 0.4840).

Table 8  Included studies in the FPD group.

Study Study period (years) Patients (n) Implants (n) Prostheses (n) Superstructure material Abutment material Implant survival (%) Prosthetic survival (%) Abutment fracture (%) Chipping (%) Screw loosenig (%) Decementation (%)
Barnea E et al.100 4.86 29 29 29 Metal-Ceramic (non-defined) - 93.10 100
Barnea E et al.100 4.86 29 29 29 Metal-Ceramic (non-defined) - 89.60 100
Brägger U et al.101 10 29 69 33 Metal-Ceramic (non-defined) - 93.9
Francetti L et al.102 6 39 18 Metal-Ceramic (precious) Ti 100 100
Göthberg C et al.103 3 26 78 26 Titanium-Ceramic Ti 94.87
Göthberg C et al.103 3 24 72 24 Titanium-Ceramic Ti 97.22
Jemt & Lekholm104 5 101 36 Metal-Resin - 97.2 100 44.44 36.11
Jemt & Lekholm104 5 158 58 Metal Resin - 97.2 100 29.31 8.62
Kreissl ME et al.105 5 159 66 Metal-Ceramic (precious) Ti 06.06 03.03
Mangano F et al.106 10 636 242 Metal-Ceramic (non-defined) - 98.4 0 2.8 1.6
Pozzi A et al.107 3 27 81 37 Veneered Zirconia Ti/Zi 96.3 100 0 8.1 0
Romeo E et al.108 7 295 137 Metal-Ceramic (precious) Ti 96.1 2.92 2.19 3.65
Romeo E et al.109 8.2 45 105 45 Metal-Ceramic (precious) Ti/Au 100 100 48.89 6.6
Romeo E et al.7 5 9 9 Metal-Ceramic (non-defined) Ti 90 0 11.11 33.33
Romeo E et al.7 5 9 9 Metal-Ceramic (non-defined) Ti 100 0 11.11 22.22

Prosthetic survival rates were 0.99 (95% CI [0.82; 1.00]) for the all-ceramic, 0.99 (95% CI [0.93; 1.00]) for the metal-based group with resin facings, and 0.96 (95% CI [0.91; 0.98]) for the ceramic-veneered group. The difference was also not significant (P = 0.3695).

Subgroup analyses for the incidence rates of screw loosening (P = 0.0641) and abutment fractures (P = 1) revealed no statistical differences among the three materials. Data concerning prosthesis fracture and decementation was only available for the metal-ceramic group. The incidence rate for chipping was significantly higher (P = 0.0072) in the metal-resin group (0.36; 95% CI [0.23; 0.52]), compared with the metal-ceramic (0.09; 95% CI [0.02; 0.31]) and the all-ceramic group (0.08; 95% CI [0.03; 0.22]).

Types of restorative materials

For the meta-analysis of implant survival rates, the results of three study cohorts from ceramic-veneered precious alloy FPDs group, two from ceramic-veneered and titanium based FPDs group, two from precious alloy-resin FPDs, and one from veneered zirconia FPDs, were included. For the analysis of the prosthetic survival rates, two study cohorts from the ceramic-veneered precious alloy FPDs group, two from precious alloy-resin FPDs, and one from veneered zirconia FPDs, were included. For the ceramic-veneered titanium group, no details regarding the prosthetic survival rates could be found. Implant and prosthetic survival rates, as well as the 95% CI, are given in Table 9. The differences in implant and prosthetic survival rates were not statistically significant (implant survival: P = 0.8249; prosthetic survival: P = 0.9486). The meta-regression-analysis showed no impact of the different observation periods for any of the groups (implant survival: P = 0.5270; prosthetic survival: P = 0.6558). The calculated implant loss rate per 10 implant years showed no statistically significant differences among the groups (P = 0,1534).

Subgroup analyses for the incidence rates of screw loosening (P = 0.0641) showed no statistically significant differences between the used materials. Data regarding prosthesis fracture, abutment fracture, and decementation was only available for the metal-ceramic group. The incidence rate for chipping was significantly higher (P = 0.0176) in the metal-resin group (0.36; 95% CI [0.23; 0.52]), compared to the metal-ceramic (0.11; 95% CI [0.01; 0.56]) and the veneered zirconia group (0.08; 95% CI [0.03; 0.22]).

Table 9  Results for exact restorative materials (FPD-group).

Material Number of studies included Implant survival rates + 95% CI Implant loss per 10 implant years Number of studies included Prosthetic survival rates + 95% CI Chipping + 95% CI
Metal-ceramic (precious) 3 0.98 [0.92; 0.99] 0.03 [0.01; 0.12] 2 0.98 [0.89; 1.00] 0.11 [0.01; 0.56]
Titanium-ceramic 2 0.96 [0.91; 0.98] 0.14 [0.06; 0.31] --- ---
Metal-resin 2 0.97 [0.94; 0.99] 0.05 [0.03; 0.11] 2 0.99 [0.93; 1.00] 0.36 [0.23; 0.52]
Veneered zirconia 1 0.96 [0.89; 0.99] 0.12 [0.04; 0.38] 1 0.99 [0.82; 1.00] 0.08 [0.03; 0.22]

Discussion

Summary of evidence

The aim of this systematic review and meta-analysis was to analyse whether the choice of prosthetic material for fixed implant-supported restorations has an impact on the survival rates of oral endosseous implants. Furthermore, additional analyses for dental prosthesis survival rates and the incidence rates of prosthetic complications were performed.

Current data regarding the influence of prosthetic materials on implant survival is unsatisfactory. To our knowledge, there is not a single study investigating the impact of the prosthetic material on implant survival. There are several reviews dealing with implant and prosthetic survival rates for all kinds of fixed prostheses, but each of these posed a different scientific question, e.g. restoration types or implant lengths, while none of them addressed the prosthetic material during data collection7,110-116. Therefore, the evidence for the influence of the prosthetic material has to be evaluated as nonexistent. Furthermore, even the abutment material as well as the abutment shape might play a role in implant survival. The most commonly used abutment material in the present study was titanium, but zirconia, alumina or gold alloy abutments were also used for the different types of restoration.

Even more interesting than the implant or prosthetic survival rates, are the associated success rates. As there are several criteria for measuring implant success or the related success of the restorations, all of these distinct criteria are used in the analysed literature, which by itself makes finding a useful comparison method challenging; some authors did not even explicitly discuss the applied criteria. Therefore, it was decided not to analyse success, but rather survival rates. A main criterion for the analysis of implant success is the marginal bone loss. Generally, there are two different possible dates to evaluate the baseline value for bone loss: the day of implant placement or the day of the insertion of the definitive restoration. Furthermore, there are several possibilities for measuring marginal bone loss (e.g. the distance between implant shoulder and crestal bone margin). Apparently, a unified method to evaluate bone loss in combination with the description of the restorative material has not been used. For this reason, evaluation of the marginal bone loss was not included in the current meta-analysis.

For a meta-regression analysis, there are two commonly used statistical models: the random and the fixed effects model. For meta-regression and subgroup analyses, the random effects model is the most often recommended model117. In the present review, there were meta-analyses showing statistically significant differences between study groups when using the fixed effects model, but the random effects model showed no statistical significance (implant survival of all-ceramic SCs vs metal-ceramic SCs; screw loosening in all analysed study groups).

The calculation of implant loss rate per 10 implant years makes the assumption that the probability of implant loss is constant over the time after placement. This type of analysis might be questionable, but it enables the inclusion and comparison of studies with different observation periods, and has been applied in previous studies118. Furthermore, the results can also be interpreted as the average implant loss rate during a period of 10 years.

To obtain an acceptable number of included studies, RCTs, controlled clinical trials, prospective studies, retrospective studies, and case series with at least 10 patients were included. In many studies, no information about the restoration material was provided. This led to the exclusion of several studies. Despite the inclusion of retrospective studies and case series, there are study groups in the present meta-analysis consisting of a single study cohort (e.g. veneered zirconia FPDs). The significance of the results concerning these groups is at least questionable.

In the SC group, 75 study populations in 61 study groups were initially investigated. Furthermore, one study was included in the tables, although it did not fit into the inclusion criteria (due to a follow-up period shorter than 3 years), but it was the only study that dealt with nanoceramics as the restorative material83. The study showed a significantly higher incidence rate for decementation of the nanoceramic single crowns, compared with the other materials, even though the observation period was lower.

Considering the focused leading question, the prosthetic material selection seems to have no influence on the survival rates of dental implants or fixed partial dentures. Among single crowns, the incidence rates for decementation were significantly higher in the nanoceramic group (0.80; 95%CI [0.67; 0.89]) relative to all the other groups, even with the shorter follow up-period. In the FPD group, the incidence rate for chipping was significantly higher in the metal-resin group (0.36; 95% CI [0.23; 0.52]).

Limitations

The results of this meta-analysis must be regarded to consider the following limitations:

Data was mostly extracted from non-comparative studies. This was done because there were no studies comparing the influence of various restorative materials on implant survival. Especially due to the fact that the use of implants is a relatively new in dentistry, it is challenging to find comparative studies for every aspect. Many factors that have been considered to be more important have been investigated in randomised studies with different study cohorts.

It is worth mentioning that the primary questions of each of the included RCTs and prospective studies did not regard the choice of restorative material. Therefore, the level of evidence might be lower than assumed by regarding the quality assessment of the included studies. The scarcity of RCTs led to a lack of high-quality studies that could be included in this meta-analysis.

As the restorative material was not the key point of the included studies, heterogeneity among them was high. Furthermore, in many studies it was not clearly stated whether the baseline was the time of implant placement or the time of prosthesis delivery. Therefore, the mean calculated observation in the study groups could be different from reality.

The glass ceramic restorations of the SC group comprised different types of glass ceramic materials. In two studies the single crowns were made of leucite ceramics and in the two other studies, the crowns were made of lithium-disilicate ceramics58,91,98. Although the material properties are different, we decided not to separate them into distinct groups as the crowns were all fabricated in a monolithic way. This seemed to have no influence on our outcome measures.

Further factors with a possible influence on survival, such as implant type, implant material, implant diameter, implant length, abutment material, location of implants, soft- or hard tissue grafting, biological complications, time of implant placement, loading protocols, type of retention, existing cantilever, or the number of implants per prosthesis, were not taken into consideration. Many of these factors are known to have an influence on implant survival and/or on the prosthetic outcome. However, due to the aforementioned heterogeneity, it was not possible to include these factors in the present meta-analysis.

Full-arch implant-supported prostheses were not included in the study. The heterogeneity of variables within this type of restoration was too large for the analysis performed here (e.g. the number of implants per prosthesis). Further research on the influence of the prosthetic materials, especially on this type of prosthesis, would be interesting, as there are no remaining teeth in full arch prostheses. Therefore, bite forces are directly transferred to the bone by the implant and the prosthetic restoration, without any buffering by teeth or the periodontal ligaments, and the impact of the restorative material on implant survival might be significant in this group. But for a representative analysis, a closer selection of inclusion criteria must be performed than was required for this study.

Conclusions

A wide range of literature is available to analyse the impact of prosthetic material selection on implant and prosthetic survival rates in fixed dental restorations. However, most of the studies investigate single crowns rather than fixed partial dentures. Despite the limitations discussed above, the following conclusions can be made:

The choice of prosthetic material seems to have no influence on implant survival rates in fixed restorations;
The prosthetic material seems to have no influence on prosthetic survival rates of fixed implant-borne restorations;
Nanoceramic SCs seem to have a higher risk of decementation relative to other materials, and;
Metal-resin FPDs seem to have higher risk of chipping relative to other materials.

For future research, controlled clinical trials are essential to minimise the heterogeneity of literature concerning material selection, thereby enhancing our knowledge about the influence of restorative material on implant survival. 

Conflict-of-interest statement

The authors declare that they have no conflict of interest.

References 

1. Moraschini V, Poubel LA, Ferreira VF, Barboza Edos S. Evaluation of survival and success rates of dental implants reported in longitudinal studies with a follow-up period of at least 10 years: a systematic review. Int J Oral Maxillofac Surg 2015;44:​377–388.

2. Bornstein MM, Halbritter S, Harnisch H, Weber HP, Buser D. A retrospective analysis of patients referred for implant placement to a speciality clinic: Indications, surgical procedures and early failures. Int J Oral Maxillofac Implants 2008;23:​1109–1116.

3. Dhingra K. Oral rehabilitation considerations for partially edentulous periodontal patients. J Prosthodont 2012;21:​494–513.

4. Millen C, Brägger U, Wittneben JG. Influence of prosthesis type and retention mechanism on complications with fixed implant-supported prostheses: a systematic review applying multivariate analyses. Int J Oral Maxillofac Implants 2015;30:​110–124.

5. Ma S, Fenton A. Screw- versus cement-retained implant prostheses: a systematic review of prosthodontic maintenance and complications. Int J Prosthodont 2015;28:​127–145.

6. Lemos CA, Ferro-Alves ML, Okamoto R, Mendonça MR, Pellizzer EP. Short dental implants versus standard dental implants placed in the posterior jaws: A systematic review and meta-analysis. J Dent 2016;47:​8–17.

7. Romeo E, Storelli S, Casano G, Scanferla M, Botticelli D. Six-mm versus 10-mm long implants in the rehabilitation of posterior edentulous jaws: a 5-year follow-up of a randomised controlled trial. Eur J Oral Implantol 2014;7:​371–381.

8. Gallucci GO, Avrampou M, Taylor JC, Elpers J, Thalji G, Cooper LF. Maxillary Implant-Supported Fixed Prosthesis: A Survey of Reviews and Key Variables for Treatment Planning. Int J Oral Maxillofac Implants 2016;Suppl:​192–207.

9. Moher D, Liberati A, Tetzlaff J, Altman DG, PRISMA Group. Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. J Clin Epidemiol 2009;62:​1006–1012.

10. Proskin HM, Jeffcoat RL, Catlin A, Campbell J Jeffcoat MK. A meta-analytic approach to determine the state of science on implant dentistry. Int J Oral Maxillofac Implants 2007;22:​11–18.

11. R Core Team. A language and environment for statistical computing. R Foundation for Statistical Computing 2015; Vienna Austria. http://www.R-project.org/

12. Schwarzer G. General Package for Meta-Analysis. R package version 4.3-2 2015; URL http://CRAN.R-project.org/package=meta

13. Viechtbauer W. Conducting meta-analyses in R with the metafor package. Journal of Statistical Software 2010;36:​1–48.

14. Bergenblock S, Andersson B, Fürst B, Jemt T. Long-term follow-up of CeraOne™ single-implant restorations: an 18-year follow-up study based on a prospective patient cohort. Clin Implant Relat Res 2012;14:​471–479.

15. Bianchi AE, Sanfilppo F. Single-tooth replacement by immediate implant and connective tissue graft: a 1-9-year clinical evaluation. Clin Oral Implants Res 2004;15:​269–277.

16. Branzén M, Eliasson A, Arnrup K, Bazargani F. Implant-Supported Single Crowns Replacing Congenitally Missing Maxillary Lateral Incisors: A 5-Year Follow-Up. Clin Implant Dent Relat Res 2015;17:​1134–1140.

17. Dierens M, De Bruyn H, Kisch J, Nilner K, Cosyn J, Vandeweghe S. Prosthetic Survival and Complication Rate of Single Implant Treatment in the Periodontally Healthy Patient after 16 to 22 Years of Follow-Up. Clin Implant Dent Relat Res 2016;18:​117–128.

18. Ekfeldt A, Fürst B, Carlsson GE. Zirconia abutments for single-tooth implant restorations: a retrospective and clinical follow-up study. Clin Oral Implants Res 2011;22:​1308–1314.

19. Grassi FR, Capogreco M, Consonni D, Bilardi D, Buti J, Kalemaj Z. Immediate Occlusal Loading of One-Piece Zirconia Implants: Five-Year Radiographic and Clinical Evaluation. Int J Oral Maxillofac Implants 2015;30:​671–680.

20. Hälg GA, Schmid J, Hämmerle CH. Bone level changes at implants supporting crowns or fixed partial dentures with or without cantilevers. Clin Oral Implants Res 2008;19:​983–990.

21. Hosseini M, Worsaae N, Schiødt M, Gotfredsen K. A 3-year prospective study of implant-supported, single-tooth restorations of all-ceramic and metal-ceramic materials in patients with tooth agenesis. Clin Oral Implants Res 2013;24:​1078–1087.

22. Lops D, Bressan E, Pisoni G, Cea N, Corazza B, Romeo E. Short implants in partially edentulous maxillae and mandibles: a 10 to 20 years retrospective evaluation. Int J Dent 2012; doi: 10.1155/2012/351793. Epub 2012 Jul 9.

23. Mangano C, Mangano F, Piattelli A, Iezzi G, Mangano A, La Colla L. Prospective clinical evaluation of 307 single-tooth morse taper-connection implants: a multicenter study. Int J Oral Maxillofac Implants 2010;25:​394–400.

24. Mangano C, Iaculli F, Piattelli A, Mangano F. Fixed restorations supported by Morse-taper connection implants: a retrospective clinical study with 10-20 years of follow-up. Clin Oral Implants Res 2015;26:​1229–1236.

25. Moberg LE, Köndell PA, Kullman L, Heimdahl A, Gynther GW. Evaluation of single-tooth restorations on ITI dental implants. A prospective study of 29 patients. Clin Oral Implants Res 1999;10:​45–53.

26. Özkan Y, Akoğlu B, Kulak-Özkan Y. Five-year treatment outcomes with four types of implants in the posterior maxilla and mandible in partially edentulous patients: a retrospective study. Int J Oral Maxillofac Implants 2011;26:​639–647.

27. Özkan Y, Özcan M, Akoğlu B, Ucankale M, Kulak-Özkan Y. Three-year treatment outcomes with three brands of implants placed in the posterior maxilla and mandible of partially edentulous patients. J Prosthet Dent 2007:​78–84.

28. Passos SP, Linke B, Larjava H, French D. Performance of zirconia abutments for implant-supported single-tooth crowns in esthetic areas: a retrospective study up to 12-year follow-up. Clin Oral Implants Res 2016;27:​47–54.

29. Spies BC, Balmer M, Patzelt SB, Vach K, Kohal RJ. Clinical and Patient-reported Outcomes of a Zirconia Oral Implant: Three-year Results of a Prospective Cohort Investigation. J Dent Res 2015;94:​1385–1391.

30. Spies BC, Stampf S, Kohal RJ. Evaluation of Zirconia-Based All-Ceramic Single Crowns and Fixed Dental Prosthesis on Zirconia Implants: 5-Year Results of a Prospective Cohort Study. Clin Implant Dent Relat Res 2015;17:​1014–1028.

31. Tartaglia GM, Sidoti E, Sforza C. Seven-year prospective clinical study on zirconia-based single crowns and fixed dental prostheses. Clin Oral Investig 2015;19:​1137–1145.

32. Thoma DS, Brandenberg F, Fehmer V, Knechtle N, HämmerleCH, Sailer I. The Esthetic Effect of Veneered Zirconia Abutments for Single-Tooth Implant Reconstructions: A Randomized Controlled Clinical Trial. Clin Implant Dent Relat Res 2015;doi:10.1111/cid.12388. [Epub ahead of print].

33. Vigolo P, Givani A. Clinical evaluation of single-tooth mini-implant restorations: a five-year retrospective study. J Prosthet Dent 2000;84:​50–54.

34. Walton TR. An Up-to-15-Year Comparison of the Survival and Complication Burden of Three-Unit Tooth-Supported Fixed Dental Prostheses and Implant-Supported Single Crowns. Int J Oral Maxillofac Implants 2015;30:​851–861.

35. Astrand P, Engquist B, Anzén B, Bergendal T, Hallman M, Karlsson U, Kvint S, Lysell L, Rundcranz T. A three-year follow-up report of a comparative study of ITI Dental Implants and Brånemark System implants in the treatment of the partially edentulous maxilla. Clin Implant Dent Relat Res 2004;6:​130–141.

36. Becktor JP, Isaksson S, Sennerby L. Endosseous implants and bone augmentation in the partially dentate maxilla: an analysis of 17 patients with a follow-up of 29 to 101 months. Int J Oral Maxillofac Implants 2007;22:​603–608.

37. Bornstein MM, Wittneben JG, Brägger U, Buser D. Early loading at 21 days of non-submerged titanium implants with a chemically modified sandblasted and acid-etched surface: 3-year results of a prospective study in the posterior mandible. J Periodontol 2010;81:​809–818.

38. Felice P, Cannizzaro G, Barausse C, Pistilli R, Esposito M. Short implants versus longer implants in vertically augmented posterior mandibles: a randomised controlled trial with 5-year after loading follow-up. Eur J Oral Implantol 2014;7:​359–369.

39. Maló P, de Araujo Nobre M, Lopes A. The prognosis of partial implant-supported fixed dental prostheses with cantilevers. A 5-year retrospective cohort study. Eur J Oral Implantol 2013;6:​51–59.

40. Nissan J, Narobai D, Gross O, Ghelfan O, Chaushu G. Long-term outcome of cemented versus screw-retained implant-supported partial restorations. Int J Oral Maxillofac Implants 2011;26:​1102–1107.

41. Ortorp A, Jemt T. Clinical experiences of implant-supported prostheses with laser-welded titanium frameworks in the partially edentulous jaw: a 5-year follow-up study. Clin Implant Dent Relat Res 1999;1:​84–91.

42. Balshi TJ, Wolfinger GJ, Wulc D, Balshi SF A prospective analysis of immediate provisionalization of single implants. J Prosthodont 2011;20:​10–15.

43. Berberi AN, Noujeim ZN, Kanj WH, Merawi RJ, Salameh ZH. Immediate Placement and Loading of Maxillary Single-Tooth Implants: A 3 Year Prospective Study of Marginal Bone Level. J Contemp Dent Pract 2014;15:​202–208.

44. Bilhan H, Mumcu E, Geçkili O, Atalay B. The evaluation of the success of immediately placed single implants: a retrospective clinical study. Implant Dent 2011;20:​215–225.

45. Bonde MJ, Stokholm R, Schou S, Isidor F. Patient satisfaction and aesthetic outcome of implant-supported single-tooth replacements performed by dental students. Eur J Oral Implantol 2013;6:​387–395.

46. Buser D, Wittneben J, Bornstein MM, Grütter L, Chappuis V, Belser UC. Stability of Contour Augmentation and Esthetic Outcomes of Implant-Supported Single Crowns in the Esthetic Zone: 3-Year Results of a Prospective Study With Early Implant Placement Postextraction. J Periodontol 2011;82:​342–349.

47. Calandriello R, Tomatis M. Immediate occlusal loading of single lower molars using Brånemark System® Wide Platform TiUnite™ implants: a 5-year follow-up report of a prospective clinical multicenter study. Clin Implant Dent Relat Res 2011;13:​311–318.

48. Cannizzaro G, Felice P, Leone M, Ferri V, Viola P, Esposito M. Immediate versus early loading of 6.5 mm-long flapless-placed single implants: a 4-year after loading report of a split-mouth randomised controlled trial. Eur J Oral Implantol 2012;2:​111–121.

49. Cannizzaro G, Leone M, Consolo U, Ferri V, Esposito M. Immediate functional loading of implants placed with flapless surgery versus conventional implants in partially edentulous patients: a 3-year randomized controlled clinical trial. Int J Oral Maxillofac Implants 2008;23:​867–875.

50. De Bruyn H, Raes F, Cooper LF, Reside G, Carriga JS, Tarrida LG, Wiltfang J, Kern M. Three-years clinical outcome of immediate provisionalization of single OsseospeedTM implants in extraction sockets and healed ridges. Clin Oral Implants Res 2013;24:​217–223.

51. Cosyn J, Eghbali A, De Bruyn H, Collys K, Cleymaet R, De Rouck T. Immediate single-tooth implants in the anterior maxilla: 3-year results of a case series on hard and soft tissue response and aesthetics. J Clin Periodontol 2011;38:​746–753.

52. Covani U, Chiappe G, Bosco M, Orlando B, Quaranta A, Barone A. A 10-year evaluation of implants placed in fresh extraction sockets: a prospective cohort study. J Periodontol. 2012;83:​1226–1234.

53. Covani U, Canullo L, Toti P, Alfonsi F, Barone A. Tissue stability of implants placed in fresh extraction sockets: a 5-year prospective single-cohort study. J Periodontol 2014;85: e323–332.

54. Davis DM, Watson RM, Packer ME. Single tooth crowns supported on hydroxyapatite coated endosseous dental implants: a prospective 5-year study on twenty subjects. Int Dent J 2004;65:​201–205.

55. Donati M, Ekestubbe A, Lindhe J, Wennström JL. Implant-supported single-tooth restorations. A 12-year prospective study. Clin Oral Implants Res 2016;27:​1207–1211.

56. Enkling N, Jöhren P, Katsoulis J, Bayer S, Jervøe-Storm PM, Mericske-Stern R, Jepsen S. Influence of platform switching on bone-level alterations: a three-year randomized clinical trial. J Dent Res 2013;92:139S–145S.

57. Fenner N, Hämmerle CH, Sailer I, Jung RE. Long-term clinical, technical, and esthetic outcomes of all-ceramic vs. titanium abutments on implant supporting single-tooth reconstructions after at least 5 years. Clin Oral Implants Res 2016;27:​716–723.

58. Glauser R, Sailer I, Wohlwend A, Studer S, Schibli M, Schärer P. Experimental Zirconia Abutments for Implant-Supported Single-Tooth Restorations in Esthetically Demanding Regions: 4-Year Results of a Prospective Clinical Study. Int J Prosthodont 2004;17:​285–290.

59. Gottfredsen K. A 10-year prospective study of single tooth implants placed in the anterior maxilla. Clin Implant Dent Relat Res 2012:14:​80–87.

60. Guarnieri R, Ceccherini A, Grande M. Single-Tooth Replacement in the Anterior Maxilla by Means of Immediate Implantation and Early Loading: Clinical and Aesthetic Results at 5 Years. Clin Implant Dent Relat Res 2015;17:​314–326.

61. Ioannidis A, Gallucci GO, Jung RE, Borzangy S, Hämmerle CH, Benic GI. Titanium-zirconium narrow-diameter versus titanium regular-diameter implants for anterior and premolar single crowns: 3-year results of a randomized controlled clinical study. J Clin Periodontol 2015;42:​1060–1070.

62. Jemt T. Cemented CeraOne® and Porcelain Fused to TiAdapt™ Abutment Single-Implant Crown Restorations: A 10-Year Comparative Follow-Up Study. Clin Implant Dent Relat Res 2009;11:​303–310.

63. Jemt T, Pettersson P. A 3-year follow-up study on single implant treatment. J Dent 1993;21:​203–208.

64. Khraisat A, Zembic A, Jung RE, Hammerle CH. Marginal bone levels and soft tissue conditions around single-tooth implants with a scalloped neck design: results of a prospective 3-year study. Int J Oral Maxillofac Implants 2013;550–555.

65. Kolgeci L, Mericske E, Worni A, Walker P, Katsoulis J, Mericske-Stern R. Technical Complications and Failures of Zirconia-Based Prostheses Supported by Implants Followed Up to 7 Years: A Case Series. Int J Prosthodont 2014;27:​544–552.

66. Lai HC, Si MS, Zhuang LF, Shen H, Liu YL, Wismeijer D. Long-term outcomes of short dental implants supporting single crowns in posterior region: a clinical retrospective study of 5-10 years. Clin Oral Implants Res 2013;24:​230–237.

67. Lang LA, Turkyilmaz I, Edgin WA, Verrett R, Garcia LT. Immediate restoration of single tapered implants with nonoccluding provisional crowns: a 5-year clinical prospective study. Clin Implant Dent Relat Res 2014;16:​248–258.

68. Lops D, Bressan E, Chipasco M, Rossi A, Romeo E. Zirconia and titanium implant abutments for single-tooth implant prostheses after 5 years of function in posterior regions. Int J Oral Maxillofac Implants 2013;281–287.

69. Mangano C, Levrini L, Mangano A, Mangano F, Macchi A, Caprioglio A. Esthetic evaluation of implants placed after orthodontic treatment in patients with congenitally missing lateral incisors. J Esthet Resto Dent 2014;26:​61–71.

70. Mangano FG, Shibli JA, Sammons RL, Iaculli F, Piattelli A, Mangano C. Short (8-mm) locking-taper implants supporting single crowns in posterior region: a prospective clinical study with 1-to 10-years of follow-up. Clin Oral Implants Res 2014;25:​933–940.

71. Mangano F, Macchi A, Caprioglio A, Sammons RL, Piattelli A, Mangano C. Survival and complication rates of fixed restorations supported by locking-taper implants: a prospective study with 1 to 10 years of follow-up. J Prosthodont 2014;26:​434–444.

72. Mericske-Stern R, Grütter L, Rösch R, Mericske E. Clinical evaluation and prosthetic complications of single tooth replacements by non-submerged implants. Clin Oral Implants Res 2001;12:​309–318.

73. Montoya-Salazar V, Castillo-Oyagüe R, Torres-Sánchez C, Lynch CD, Gutiérrez-Pérez JL, Torres-Lagares D. Outcome of single immediate implants placed in post-extraction infected and non-infected sites, restored with cemented crowns: a 3-year prospective study. J Dent 2014;645–652.

74. Nejatidanesh F, Moradpoor H, Savabi O. Clinical outcomes of zirconia-based implant- and tooth-supported single crowns. Clin Oral Investig 2016; 20:​169–178.

75. Palmer RM, Palmer PJ, Smith BJ. A 5-year prospective study of Astra single tooth implants. Clin Oral Implants Res 2000;11:​179–182.

76. Perelli M, Abundo R, Corrente G, Saccone C. Short (5 and 7 mm long) porous implants in the posterior atrophic maxilla: a 5-year report of a prospective single-cohort study. Eur J Oral Implantol 2012;5:​265–272.

77. Pieri F, Aldini NN, Marchetti C, Corinaldesi G. Esthetic outcome and tissue stability of maxillary anterior single-tooth implants following reconstruction with mandibular block grafts: a 5-year prospective study. Int J Oral Maxillofac Implants 2013; 28: 270 – 280.

78. Proussaefs P, Lozada J. Immediate loading of hydroxyapatite-coated implants in the maxillary premolar area: three-year results of a pilot study. J Prosthet Dent 2004;91:​228–233.

79. Rinke S, Lattke A, Eickholz P, Kramer K, Ziebolz D. Practice-based clinical evaluation of zirconia abutments for anterior single-tooth restorations. Quintessence Int 2015;46:​19–29

80. Rinke S, Roediger M, Eickholz P, Lange K, Ziebolz D. Technical and biological complications of single-molar implant restorations. Clin Oral Implants Res 2015; 26:​1024–1030.

81. Roccuzzo M, Gaudioso L, Bunino M, Dalmasso P. Long-term stability of soft tissues following alveolar ridge preservation: 10-year results of a prospective study around nonsubmerged implants. Int J Periodontics Restorative Dent 2014;34:​795–804.

82. Romanos GE, Aydin E, Locher K, Nentwig GH. Immediate vs. delayed loading in the posterior mandible: a split-mouth study with up to 15 years of follow-up. Clin Oral Implants Res 2016;e74–79.

83. Romeo E, Chiapasco M, Ghisolfi M, Vogel G. Long-term clinical effectiveness of oral implants in the treatment of partial edentulism. Seven-year life table analysis of a prospective study with ITI dental implants system used for single-tooth restorations. Clin Oral Implants Res 2002;13:​133–143.

84. Rossi F, Lang NP, Ricci E, Ferraioli L, Marchetti C, Botticelli D. Early loading of 6-mm-short implants with a moderately rough surface supporting single crowns--a prospective 5-year cohort study. Clin Oral Implant Res 2015; 26:​471–477.

85. Rossi F, Botticelli D, Cesaretti G, De Santis E, Storelli S, Lang NP. Use of short implants (6 mm) in a single-tooth replacement: a 5-year follow-up prospective randomized controlled multicenter clinical study. Clin Oral Implant Res 2016;27:​458–464.

86. Schepke U, Meijer HJ, Vermeulen KM, Raghoebar GM, Cune MS. Clinical Bonding of Resin Nano Ceramic Restorations to Zirconia Abutments: A Case Series within a Randomized Clinical Trial. Clin Implant Dental Relat Res 2015;18:​984–982.

87. Schropp L, Isidor F. Clinical outcome and patient satisfaction following full-flap elevation for early and delayed placement of single-tooth implants: a 5-year randomized study. Int J Oral Maxillofac Implants 2008;23:​733–743.

88. Schropp L, Wenzel A, Stavropoulos A. Early, delayed, or late single implant placement: 10-year results from a randomized controlled clinical trial. Clin Oral Implants Res 2014;25:​1359–1365.

89. Sorrentino R, Galasso L, Tetè S, De Simone G, Zarone F. Clinical evaluation of 209 all-ceramic single crowns cemented on natural and implant-supported abutments with different luting agents: a 6-year retrospective study. Clin Implant Dent Relat Res 2012;14:​184–197.

90. Turkyilmaz I, Avci M, Kuran S, Ozbek EN. A 4-year prospective clinical and radiological study of maxillary dental implants supporting single-tooth crowns using early and delayed loading protocols. Clin Oral Implants Res 2007;9:​222–227.

91. Vanlioglu BA, Özkan Y, Evren B, Özkan YK. Experimental custom-made zirconia abutments for narrow implants in esthetically demanding regions: a 5-year follow-up. Int J Oral Maxillofac Implants 2012;27:​1239–1242.

92. Vigolo P, Givani A, Majzoub Z, Cordioli G. A 4-year prospective study to assess peri-implant hard and soft tissues adjacent to titanium versus gold-alloy abutments in cemented single implant crowns. J Prosthodont 2006;15:​250–256.

93. Visser A, Raghoebar GM, Meijer HJ, Meijndert L, Vissink A. Care and aftercare related to implant-retained dental crowns in the maxillary aesthetic region: a 5-year prospective randomized clinical trial. Clin Implant Dent Relat Res 2011;13:​157–167.

94. Weber HP, Kim DM, Ng MW, Hwang JW, Fiorellini JP. Peri-implant soft-tissue health surrounding cement- and screw-retained implant restorations: a multi-center, 3-year prospective study. Clin Oral Implants Res 2006;17:​375–379.

95. Worni A, Kolgeci L, Rentsch-Kollar A, Katsoulis J, Mericske-Stern R. Zirconia-Based Screw-Retained Prostheses Supported by Implants: A Retrospective Study on Technical Complications and Failures. Clin Implant Dent Relat Res 2015;17:​1073–1081.

96. Zarone F, Sorrentino R, Vaccaro F, Russo S, De Simone G. Retrospective clinical evaluation of 86 Procera AllCeram anterior single crowns on natural and implant-supported abutments. Clin Implant Dent Relat Res 2005; 7 Suppl:​95–103.

97. Zembic A, Bösch A, Jung RE, Hämmerle CH, Sailer I. Five-year results of a randomized controlled clinical trial comparing zirconia and titanium abutments supporting single-implant crowns in canine and posterior regions. Clin Oral Implants Res 2013;24:​284–390.

98. Zembic A, Philipp AO, Hämmerle CH, Wohlwend A, Sailer I. Eleven-Year Follow-Up of a Prospective Study of Zirconia Implant Abutments Supporting Single All-Ceramic Crowns in Anterior and Premolar Regions. Clin Implant Dent Relat Res. 2015;17Suppl 2;e417–426.

99. Zhao X, Qiao SC, Shi JY, Uemura N, Arai K, Lai HC. Evaluation of the clinical and aesthetic outcomes of Straumann® Standard Plus implants supported single crowns placed in non-augmented healed sites in the anterior maxilla: a 5-8 years retrospective study. Clin Oral Implants Res 2016;27:​106–112.

100. Barnea E, Tal H, Nissan J, Tarrasch R, Peleg M, Kolerman R. The Use of Tilted Implant for Posterior Atrophic Maxilla. Clin Implant Dent Relat Res 2016;18:​788–800.

101. Brägger U, Karoussis I, Persson R, Pjetursson B, Salvi G, Lang N. Technical and biological complications/failures with single crowns and fixed partial dentures on implants: a 10-year prospective cohort study. Clin Oral Implants Res 2005;16:​326–334.

102. Francetti L, Azzola F, Corbella S, Taschieri S, Del Fabbro M. Evaluation of clinical outcomes and bone loss around titanium implants with oxidized surface: six-year follow-up results from a prospective case series study. Clin Implant Dent Relat Res 2014;16:​81–88.

103. Göthberg C, André U, Gröndahl K, Thomsen P, Slotte C. Bone Response and Soft Tissue Changes Around Implants With/Without Abutments Supporting Fixed Partial Dentures: Results From a 3-Year, Prospective, Randomized, Controlled Study. Clin Implant Dent Relat Res 2016;18:​309–322.

104. Jemt T, Lekholm U. Oral implant treatment in posterior partially edentulous jaws: a 5-year follow-up report. Int J Oral Maxillofac Implants 1993;8:​635–640.

105. Kreissl ME, Gerds T, Muche R, Heydecke G, Strub JR. Technical complications of implant-supported fixed partial dentures in partially edentulous cases after an average observation period of 5 years. Clin Oral Implants Res 2007 18:​720–276.

106. Mangano F, Macchi A, Caprioglio A, Sammons RL, Piattelli A, Mangano C. Survival and complication rates of fixed restorations supported by locking-taper implants: a prospective study with 1 to 10 years of follow-up. J Prosthodont 2014;23:​434–444.

107. Pozzi A, Sannino G, Barlattani A. Minimally invasive treatment of the atrophic posterior maxilla: a proof-of-concept prospective study with a follow-up of between 36 and 54 months. J Prosthet Dent 2012; 108:286 –297.

108. Romeo E, Lops D, Margutti E, Ghisolfi M, Chiapasco M, Vogel G. Long-term survival and success of oral implants in the treatment of full and partial arches: a 7-year prospective study with the ITI dental implant system. Int J Oral Maxillofac Implants 2004; 19:​247–259.

109. Romeo E, Tomasi C, Finini I, Casentini P, Lops D. Implant-supported fixed cantilever prosthesis in partially edentulous jaws: a cohort prospective study. Clin Oral Implants Res 2009; 20:​1278–1285.

110. Albrektsson T, Donos N. Implant survival and complications. The Third EAO consensus conference 2012. Clin Oral Implants Res 2012;23 Suppl6:​63–65.

111. Jung RE, Pjetursson BE, Glauser R, Zembic A, Zwahlen M, Lang NP. A systematic review of the 5-year survival and complication rates of implant-supported single crowns. Clin. Oral Impl Res 19,2008;119–130.

112. Hjalmarsson L, Gheisarifar M, Jemt T. A systematic review of survival of single implants as presented in longitudinal studies with a follow-up of at least 10 years. Eur J Oral Implantol. 2016;9:​155–62.

113. Jung RE, Zembic A, Pjetursson BE. Zwahlen M, Thoma DS. Systematic review of the survival rate and the incidence of biological, technical, and aesthetic complications of single crowns on implants reported in longitudinal studies with a mean follow-up of 5 years. Clin. Oral Implants Res 2012;Suppl6:​2–21.

114. Bryant SR, MacDonald-Jankowski D, Kim K. Does the type of implant prosthesis affect outcomes for the completely edentulous arch? Int J Oral Maxillofac Implants. 2007; 22 Suppl:​117–139.

115. Crespi R, Capparè P, Gastaldi G, Gherlone EF. Immediate occlusal loading of full-arch rehabilitations: screw-retained versus cement-retained prosthesis. An 8-year clinical evaluation. Int J Oral Maxillofac Implants; 29:​1406–1411.

116. Maló P, de Araújo Nobre M, Lopes A, Francischone C, Rigolizzo M. “All-on-4” Immediate-Function Concept for Completely Edentulous Maxillae: A Clinical Report on the Medium (3 Years) and Long-Term (5 Years) Outcomes. Clin Implant Dent Relat Res 2012;14 Suppl1:e139–150.

117. Thompson SG, Higgins JPT. How should meta-regression analyses be undertaken and interpreted? Stat Med 2002; 21:​1559–1573.

118. Kern JS, Kern T, Wolfart S, Heussen N. A systematic review and meta-analysis of removable and fixed implant supported prostheses in edentulous jaws: post-loading implant loss. Clin Oral Impl Res 2016;27:​174–195.

 

Authors

 

 

Samir Abou-Ayash Department of Prosthodontics, School of Dentistry, Medical Center – University of Freiburg, Freiburg, Germany; Faculty of Medicine, Medical Center – University of Freiburg, Freiburg, Germany

Malin Strasding Department of Prosthodontics, School of Dentistry, Medical Center – University of Freiburg, Freiburg, Germany; Faculty of Medicine, Medical Center – University of Freiburg, Freiburg, Germany

Gerta Rücker  Institute for Medical Biometry and Statistics, Medical Center – University of Freiburg, Freiburg, Germany; Faculty of Medicine, Medical Center – University of Freiburg, Freiburg, Germany

Wael Att Department of Prosthodontics, School of Dentistry, Medical Center - University of Freiburg, Hugstetter Str. 55, 79106 Freiburg, Germany; Faculty of Medicine, Medical Center – University of Freiburg, Freiburg, Germany 

Correspondence to:
Prof Dr Wael Att, Department of Prosthodontics, School of Dentistry, Medical Center - University of Freiburg, Hugstetter Str. 55, 79106 Freiburg, Germany

Email: wael.att@uniklinik-freiburg.de

Fax: +4976127049250,

Tel: +4976127047380