Improved volume and contour stability with thin socket-shield preparation in immediate implant placement and provisionalization in the esthetic zone

Improved volume and contour stability with thin socket-shield preparation in immediate implant placement and provisionalization in the esthetic zone

MENA Clinical Dentistry

1. December 2019

Serhat Aslan

Tooth replacement with a dental implant in the esthetic zone is a challenging treatment modality for the clinician. Each step of the treatment from tooth extraction to the definitive restoration should be performed meticulously to achieve a good esthetic outcome.

Negative effects of the extraction can be minimized by various treatment protocols. Recent developments involving partial root retention (socket-shield technique) offer enhanced buccal tissue contour in these cases. This clinical report presents a slight modification to the socket-shield technique by preparing a thin shield and performing immediate implant placement. The gap between the shield and the implant was filled with a bone graft, and a screw-retained provisional restoration supported the natural emergence profile. Through the 6-month healing period, and after 1 year of function, the natural appearance of the buccal contour was maintained. Cone beam computed tomography (CBCT) and volumetric analysis confirmed the presence of the buccal bone plate and volume stability. This case report demonstrates that improved buccal contour stability and a high esthetic outcome can be achieved with thin socket-shield preparation (Int J Esthet Dent 2018;13:172–183).

Introduction

Various clinical studies have clearly demonstrated that bone remodeling following tooth extraction results in dimensional changes of the alveolar ridge contour.1-3 The amount of resorption is more pronounced in the buccal aspect compared to the lingual aspect of the alveolar ridge.4-6 

Replacement of the missing tooth with a dental implant, however, requires sufficient hard and soft tissue dimension to create a natural emergence of the restoration.7,8 To compensate for the negative outcomes of the extraction, various treatment modalities have been proposed such as ridge preservation with bone substitutes,9-11 socket sealing with a free gingival graft,12,13 and immediate implant placement with or without a connective tissue graft and/or provisional restoration.14-20 However, the entire preservation of the socket dimensions has not yet been demonstrated.21,22

Several clinical studies have tested the idea of root retention, either of the decoronated roots or partial retention on the buccal side. Vertical bone formation over the decoronated root was observed in a few studies.23,24 In pontic sites, the alveolar ridge contour can be maintained by the retention of the decoronated roots.25 For the implant sites in particular, partial retention of a buccal root fragment in contact with the dental implant was proposed by Hürzeler et al26 in immediate implant placement surgery. Histological analysis suggested that the buccal bone plate was preserved without any inflammatory or resorptional response with the socket-shield technique. Also, Davarpanah and Szmukler-Moncler27 reported implant placement in contact with ankylosed root fragments without any adverse events after a period of 1 year post-loading. Moreover, modification of the socket-shield technique suggesting the preservation of interproximal root fragments allowed for the maintenance of the interimplant papilla due to the natural attachment of the root fragments.28,29

Successful implementation of this technique as well as modifications have been demonstrated by several researchers.26,28-30 However, none of these studies have suggested the retention of the thin root fragment. The aim of this clinical report was to assess and demonstrate the effect of thin socket-shield preparation in combination with immediate implant placement and provisionalization.

Clinical report

A 32-year-old female patient was referred to our dental office requesting the esthetic replacement of a maxillary right central incisor. The tooth exhibited horizontal fracture due to several treatment attempts and incomplete endodontic therapy (Fig 1). Following discussion of the treatment plan, the patient decided to receive immediate implant placement and provisionalization with the socket-shield technique, and gave her written informed consent. The patient was a non-smoker and was systemically healthy. Radiographic examination revealed a periapical lesion (Fig  2).

Fig 1 Baseline labial view of the fractured maxillary right central incisor.
Fig  2 Baseline periapical radiograph.

 The surgical site was disinfected prior to extraction with a 0.12% chlorhexidine digluconate solution. Following local anesthesia, measurements of probing depth and bone sounding with a PCP-UNC  15 periodontal probe (Hu-Friedy) confirmed the presence of an intact buccal bone plate without vertical root fracture. The tooth was sectioned mesiodistally by a high-speed diamond bur, and the palatal side of the root was then removed atraumatically with a flapless procedure. The remaining buccal half of the root was prepared until the crescent-shaped 1-mm thickness of the shield was formed (Fig 3).

Fig  3 Crescent-shaped thin shield preparation

To respect the biologic width, the height of the shield was reduced to 2 mm apical to the gingival margin, and 1 mm coronal to the buccal bone crest. After the completion of the shield preparation, implant osteotomy was performed engaging two-thirds of the palatal bone to obtain the ideal three-dimensional (3D) position and high primary stability. A 3.9 × 11.5 mm implant (V3, MIS Implant Technologies) was inserted and positioned 4 mm apical to the prospective gingival margin (Figs  4 and 5).

The remaining gap between the shield and implant was grafted with demineralized bovine bone mineral (Bio-Oss, Geistlich Pharma). A non-functional, screw-retained provisional composite resin restoration was tightened onto the implant at a torque of 15 Ncm (Figs  6 and 7).

At the end of the surgery, an analgesic was administered (Brufen 600 mg, Abbott Laboratories), and the patient was instructed to take a subsequent dose 8 h later. To control possible bacterial contamination, an antibiotic (Augmentin BID 1000 mg, GlaxoSmithKline) was prescribed during the first postoperative week. The patient was asked to refrain from brushing the surgical site for the 2-week postoperative period, but to rinse with 0.12% chlorhexidine digluconate for 1 min twice daily. A soft diet as well as the avoidance of function at the implant site was also advised. At the end of 1 week, the surgical site had healed without event except for a slight oedema on the buccal side, which resolved at 2 weeks (Fig  8).

Fig  8  Uneventful healing at 1 week 

After an uneventful 6-month healing period, the screw-retained provisional restoration was modified by the addition of composite resin to convert the emergence profile and create a harmonious gingival margin (Figs  9 and 10). After 2 months of soft tissue conditioning, a polyvinylsiloxane impression was taken using a customized impression coping (Figs  11 to 14).

An individually fabricated lithium disilicate abutment (IPS e.max Press MO 1, Ivoclar Vivadent) luted to the titanium base was tightened onto the implant at a torque of 35 Ncm (Figs  15 to 17). Finally, the definitive lithium disilicate crown (IPS e.max Press LT A1) was cemented using a self-adhesive resin cement (RelyX U200, 3M ESPE). The patient was fully satisfied with the esthetics of the restoration as well as with the preservation of the natural convex buccal contour equal to the adjacent central incisor (Figs  18 to 20). The cone beam computed tomography (CBCT) image confirmed the presence of a very thin buccal bone plate (= 0.39 mm) after 1 year of function (Figs  21 to 23). 

 

 

Volumetric evaluation

The integrated comparison software (Cerec SW 4.4.3, Sirona) was used to superimpose the 3D datasets from pairs of dental stone replicas and to calculate the alterations. Measurements were performed in the buccopalatal direction parallel to the implant axis in 3 slices: 1, 4, and 7 mm below the gingival margin (Fig  24). The palatal side showed more volumetric changes compared to the buccal side in each slice at different levels (Figs  25 and 26; Table  1).

Table 1 Volumetric alterations from superimposed digital impressions

Slice 1 Slice 2 Slice 3
Buccal Palatal Buccal Palatal Buccal Palatal
1mm 0.09 0.97 0.02 1.21 0.04 1.03
4mm 0.15 0.72 0.10 0.63 0.04 0.51
7mm 0.72 0.48 0.50 0.35 0.34 0.35

Discussion

This case report confirms that thin socket-shield preparation in combination with immediate implant placement and provisionalization can maintain the natural appearance of the buccal contour of the implant site as well as esthetics. The term “thin socket-shield” in this case report was used to describe the 1-mm thickness of a crescent-shaped buccal root fragment that was prepared prior to implant osteotomy.

Replacement of a failing tooth with implant placement is a significant challenge in the esthetic zone and is affected by critical elements such as the timing of placement, topography of the alveolar socket, soft and hard tissue dimensions, the surgeon’s skill, and the implant position and design.7,8,15,17 Besides these critical elements, the behavior of patients (eg, compliance, smoking, maintenance of postoperative oral hygiene) may also influence the clinical outcome, especially in the esthetic zone.

The timing of implant placement has been debated following esthetic failures with immediate implant placement.8 The concept of early implant placement has been suggested to reduce the failure rate from an esthetic point of view.31-33 A period of 4 to 8 weeks of soft tissue healing allows the clinician to handle the surgical site. However, this technique comprises harvesting autogenous bone chips apical to the surgical site as well as bone graft and collagen barrier placement, and a periosteal releasing incision for passive flap closure. From the patient’s perspective it requires additional invasive procedures and seems more expensive compared to immediate implant placement.

The socket-shield technique in combination with immediate implant placement has the potential to preserve the natural appearance and can be considered minimally invasive as it does not require flap elevation or second-stage surgery, a periosteal releasing incision, or the additional use of autogenous bone chips and a barrier membrane. However, the shield preparation and implant positioning are technique-sensitive and require surgical expertise to maximize the esthetic outcome.30

The original technique proposed by Hürzeler et al26 suggests the use of implant drills on the decoronated root. Not only is the use of these drills expensive, there is also the possibility of endangering the integrity of the root by microcracks during the enlargement of the osteotomy site and the unwanted removal of some shield parts. Apart from this, the thickness of the shield may vary according to the buccopalatal dimension of the tooth and drilling location. Additionally, clinical application of the original technique entails a contact between the shield and the implant. In case of a complication, the removal of the shield may cause buccal dehiscence and rather a large area to regenerate with the guided bone regeneration (GBR) technique. By preparing a crescent-shaped, 1-mm- thick shield and inserting the implant away from the shield, extensive bone regeneration surgery in case of a removal may be prevented, as there will be bone-like tissue on the buccal surface of the implant and adding a soft tissue graft20 may compensate for the volume of the shield. This could be considered a major advantage for thin socket-shield preparation by eliminating the contact with the implant. However, the buccopalatal dimension of the maxillary lateral incisor might not allow the gap formation between the thin shield and the implant during the procedure, in which case the implant may have direct contact with the thin shield.

Evidence-based dentistry has clearly demonstrated the relevant factors for successful immediate implant placement; however, different outcomes are obtained in infected sites either with endodontic or periodontal lesions.34-36 Even an endodontically treated asymptomatic tooth could be a reason for implant failure.37 The success identified in this clinical report should be interpreted with caution, especially for root-retained procedures with immediate implant placement, and long-term results are required.

Volumetric alteration analyses have demonstrated that the remodeling of the alveolar bone following tooth extraction significantly influences the soft and hard tissue volume. In the case presented here, the palatal site showed 1.21 mm of change at the most coronal aspect, which corresponded to the level of the preexisting bundle bone. However, the buccal site showed only 0.02 mm of change at this level. This could be attributed to the preservation of the natural periodontium by the shield preparation, and resulted in a superior outcome on the buccal side.

Conclusion

Maintaining the natural emergence profile and buccal volume is challenging when replacing a failing tooth with a dental implant. Within the limitations of this report, the improved volume and contour stability can be obtained by retaining a thin shield in immediate implant placement. While this approach is less invasive for the patient, the technique requires significant surgical skill. Further clinical studies with long-term results should be conducted.

 

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Serhat Aslan
Dr

Private Practice, Izmir, Turkey
Meksika Sk.13/ 4 Alsancak,
Izmir, 35220 Turkey;
Tel: +90 232 4210108