|Year : 2022 | Volume
| Issue : 3 | Page : 75-81
Efficacy of Socket-Shield Technique on Tissue Stability of Immediate Implant Placement: A Systematic Review with Meta-Analysis and Trial Sequential Analysis
Reza Birang1, Jaber Yaghini2, Shirin Zahra Farhad3, Mahsa Ahmadi Shadmehri4, Zohreh Afshari5, Pedram Iranmanesh6, Mohammad Reza Maracy7, Amir Khorasani Zadeh8
1 Department of Periodontology, Dental Research Center, Dental Research Institute, School of Dentistry, Isfahan University of Medical Sciences, Isfahan, Iran
2 Dental Implants Research Center, Department of Periodontics, Dental Research Institute, School of Dentistry, Isfahan University of Medical Sciences, Isfahan, Iran
3 Dental Implant Research Center, Department of Periodontics, Dental Research Institute, School of dentistry, Isfahan University of Medical Sciences, Isfahan, Iran
4 Department of Periodontics, Faculty of Dentistry, Isfahan (Khorasgan) Branch, Islamic Azad University, Isfahan, Iran
5 Department of Periodontics, Dental Implants Research Center, Dental Research Institute, School of Dentistry, Isfahan University of Medical Sciences, Isfahan, Iran
6 Dental Research Center and Department of Endodontics, School of Dentistry, Dental Research Institute, Isfahan University of Medical Sciences, Isfahan, Iran
7 Department of Epidemiology and Biostatistics, School of Public Health, Isfahan University of Medical Sciences, Isfahan, Iran
8 Student Research Committee, Faculty of dentistry, Isfahan (khorasgan) Branch, Islamic Azad university, Isfahan, Iran
|Date of Submission||15-Nov-2021|
|Date of Decision||21-Jun-2022|
|Date of Acceptance||07-Jul-2022|
|Date of Web Publication||19-Sep-2022|
Mahsa Ahmadi Shadmehri
Department of periodontics, Faculty of dentistry, Isfahan (khorasgan) Branch, Islamic Azad university, Isfahan
Shirin Zahra Farhad
Department of Periodontics, Dental Research Institute, School of dentistry, Isfahan University of Medical Sciences, Isfahan
Source of Support: None, Conflict of Interest: None
Objective: To compare the socket-shield technique (SST) with the conventional method of immediate implant placement (IIP) regarding stabilization of buccal hard and soft tissue, and esthetic management. Method and Materials: Randomized controlled trials (RCT) investigating SST, published in English, were searched in MEDLINE/PubMed, Web of Science, Scopus, Cochrane, ProQuest, OpenGrey, and Embase until May May 2021, in June 2021. The quality assessment of included RCTs was conducted using the Cochrane Collaboration’s tools. A STATA version 16 was used to determine mean difference with 95% confidence intervals for buccal plate width (BPW), buccal plate height (BPH), pink esthetic score (PES), and implant stability quotient for 3, 6, and 12 months follow-up subgroups. Results: Out of 4617 records, 10 RCTs were finally included for the review and meta-analysis. Regarding BPW, significant differences were observed in favor of SST after 6 months. Also significant difference was detected in BPH and PES in favor of SST compared to the conventional method for all time points. However, no significant difference was found regarding implant stability between the two groups. Conclusion: SST yields better outcomes in dimensional changes of bone and soft tissue, and is found to be superior to conventional IIP regarding esthetic results and stability of hard and soft tissue around implants.
Keywords: Socket-shield technique, immediate implantation, buccal bone loss
|How to cite this article:|
Birang R, Yaghini J, Farhad SZ, Shadmehri MA, Afshari Z, Iranmanesh P, Maracy MR, Zadeh AK. Efficacy of Socket-Shield Technique on Tissue Stability of Immediate Implant Placement: A Systematic Review with Meta-Analysis and Trial Sequential Analysis. Dent Hypotheses 2022;13:75-81
|How to cite this URL:|
Birang R, Yaghini J, Farhad SZ, Shadmehri MA, Afshari Z, Iranmanesh P, Maracy MR, Zadeh AK. Efficacy of Socket-Shield Technique on Tissue Stability of Immediate Implant Placement: A Systematic Review with Meta-Analysis and Trial Sequential Analysis. Dent Hypotheses [serial online] 2022 [cited 2022 Dec 1];13:75-81. Available from: http://www.dentalhypotheses.com/text.asp?2022/13/3/75/356341
| Introduction|| |
The inevitable resorption of the alveolar ridge after tooth extraction, mainly due to the loss of periodontal ligament (PDL), causes soft tissue recession, which is associated with esthetic issues for the patient, particularly in the anterior maxillary areas.
The socket-shield technique (SST) was first introduced by Hurzeler et al. to preserve the buccal bone after tooth extraction by placing implants in proximity to the remaining root to preserve PDL., Histological studies in animal models have reported the formation of cement on the surface of the implant in contact with the root, and human studies on failed implants have shown bone formation in the distance between the root and the implant.
This systematic review and meta-analysis aimed to review clinical studies comparing the SST method with the conventional method of immediate implant placement (IIP) to determine the efficacy of this technique regarding stabilization of buccal hard and soft tissue, and esthetic management in IIP.
| Materials and Methods|| |
Registration and structured question
This systematic review protocol was registered in the International Prospective Register of Systematic Reviews (PROSPERO) under registration number CRD42021233085. The review is based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and Cochrane Collaboration guidelines., The question was “is SST successful in maintaining hard and soft tissue stability in immediate implantation?” and PICOS was, − (a) population: patients in need of immediate implantation in esthetic area; (b) intervention: implant placement with SST; (c) comparison: implant placed with conventional technique; (d) outcome: dimensional changes of buccal bone and soft tissue; and (e) study design: randomized controlled trial (RCT).
Search strategies and eligibility criteria
An electronic search restricted to May 2021 was undertaken, including MEDLINE/PubMed, Web of Science, Scopus, in June 2021, Cochrane, ProQuest, OpenGrey, and Embase. Furthermore, the bibliographies of all included records were screened manually to identify further relevant studies. Inclusion criteria were: RCTs investigating SST published in English. Exclusion criteria were: animal studies, in vitro studies, case reports, case series, and literature reviews [Table S1].
Screening and data extraction
After removing duplicate records, the titles and abstracts of the search results were screened initially by two independent researchers (MAS and SZF). Records were evaluated for full text if they met the inclusion criteria. Any disagreement between authors was resolved by discussion with a third review researcher (ZA). In case of inadequate information, the corresponding authors were contacted via e-mail. The following data were extracted by one of the reviewers (MAS): first author’s names, year of publication, country of setting, trail design, follow-up period, number of patients, and the result of buccal plate width (BPW) and buccal plate height (BPH), pink esthetic score (PES), and implant stability quotient (ISQ), and success rate assessment. For quality assessment, RCTs were independently assessed by two reviewers (MAS and ZA) using the Cochrane Collaboration’s tool for human randomized trials.
Meta-analysis was carried out by STATA version 16 (StataCorp, College Station, TX) and metaphor R packages (R Foundation for Statistical Computing, Vienna, Austria) to determine the mean difference (MD) with 95% confidence intervals (95% CI) for BPW, BPH, PES and ISQ value. The subgroup was conducted based on the time of follow-up period comprising 3, 6, and 12 months. However, measurements of 4 months period in two studies, and 7 to 8 months in two, studies were categorized into 3 and 6 months subgroups, respectively. The unit of analysis was the number of implants. The statistical heterogeneity was obtained by the I2 statistic and a value of >50% is considered substantial heterogeneity. Publication bias was assessed with Egger and Begg tests. The nonparametric trim-and-fill test was conducted to declare any possible missing (unpublished) studies and estimated the MDs by considering those. Trial sequential analysis (TSA) was carried out using the 0.9.5.10 Beta version of the TSA software package (Copenhagen, Denmark, https://ctu.dk/tsa/downloads/) based on the MD of each subgroup, 5% type I error, 80% power, and heterogeneity suggested via model variance.
| Results|| |
Characteristics of studies
Out of 4617 retrieval records in the initial search, 2421 duplicate records were removed. After screening titles and abstracts of 2196 records, 12 studies were eligible for full-text review. Two studies were excluded, due to the lack of sufficient data, and 10 studies were included in a systematic review and meta-analysis [Figure S1].
A total of 143 and 142 immediate implants were placed with SST and conventional protocol, respectively, and all were located in the maxillary esthetic area. Except for three studies,,, implants were immediately loaded with provisional fixed prosthesis. Four studies filled the buccal gap between the shield and implant fixture with xenograft bone material,, and the other five studies did not use any bone material or guided bone regeneration (GBR) process.,,,, One study used alloplastic graft material for gap filling. All studies evaluated the dimensional bone changes by the means of cone-beam computed tomography (CBCT) except for two studies, which performed the analysis on intraoral periapical radiographs with a parallel technique., For BPW, three studies assessed the parameter in 3 months,,, five for 6 months,,,,, and one in 12 months. The BPH was evaluated in 3, 6, and 12 months by four,,,, six,,,, and two studies,, respectively. The PES was evaluated immediately, 3, 6, and 12 months after surgery by three,,, two,, four,,,, and five studies,,,,, respectively. The ISQ was measured immediately in three studies,,, one study reported the outcome in 4 months and another in 6 months [Tables S2 and S3].
Risk of bias
About 100% and 70% of the studies were categorized as high risk for performance and detection bias, respectively. Half of the studies (50%) were classified as high risk for selection bias. All (100%) studies were at low risk of bias for other issues [Figure 1].
|Figure 1 Risk of bias of the included studies presented with low (green), and high (red) risk of bias.|
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Changes in width of buccal bone plate
While no significant difference was reported for changes in BPW after 3 months’ follow-up after IIP with/without SST (MD: 0.12, 95% CI: 0.00–0.25, I2 = 79%), a statistically significant difference was noted for 6 months’ time period (MD: 0.37, 95% CI: 0.02–0.71, I2 = 99%) [Figure 2]. Baujat plots showed that Tiwari et al. had the most significant impact on the overall result of meta-analyses for changes in BPW [Figure S2]. The 12-month BPW was evaluated in a study, so a meta-analysis was not conducted for this follow-up period.
|Figure 2 Forest plot of conventional IIP versus IIP with SST for (a) 3 month BPH, (b) 6 months BPH, (c) 12 months BPH, (d) 3 months BPW, (e) 6 months BPW, (f) immediate PES, (g) 3 months PES, (h) 6 months PES, (i) 12 months PES, and (j) immediate ISQ. BPH, buccal plate height; BPW, buccal plate width; ISQ, implant stability quotient; PES, pink esthetic score; REML, restricted maximum-likelihood.|
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Changes in height of buccal bone plate
In all follow-up period including 3, 6, and 12 months, changes in BPH showed statistically significant difference in favor of SST group (MD: 0.43, 95% CI: 0.19–0.67, I2 = 87%; MD: 0.65, 95% CI: 0.37–0.94, I2 = 97%; and MD: 0.27, 95% CI: 0.11–0.42, I2 = 62% for 3, 6, and 12 months, respectively). Baujat plots indicated that Atef et al. and Fattouh had the highest impact on the heterogeneity of changes in BPH.
Pink esthetic score
The meta-analysis showed no significant difference at the time of implant placement (MD: −0.44, 95% CI: −1.13–0.26, I2 = 51%). However, significant difference in favor of SST at 3, 6, and 12 months were indicted (MD: 0.90, 95% CI: 0.38–1.42, I2 = 0%; MD: 1.41, 95% CI: 0.23–2.59, I2 = 86%; and MD: 1.15, 95% CI: 0.31–1.99, I2 = 88%; respectively). Baujat plots demonstrated that Abd-Elrahman et al. had the most impact on the overall outcome of meta-analyses and heterogeneity for PES of immediate time of implant placement and 6-month follow-up. Likewise, Hana and Omar and Bramanti et al. were the most cause of heterogeneity for 3 and 12 months follow-ups respectively.
Implant stability quotient
The meta-analysis showed no significant difference for ISQ at the time of placement (MD: 0.85, 95% CI: −0.49–2.18, I2 = 16%). Considering the Baujat plot, the highest heterogeneity was contributed to Abd-Elrahman et al. ISQ for 3 and 6-month follow-up periods each were evaluated in a study,; hence, the meta-analysis was not conducted in this regard.
Except for mild pain and swelling following the implant placement, no other clinical complications and adverse events were reported. In one study, exposure of the root fragment was observed in two cases of the SST group, and inadequate keratinized tissue band and gum recession in five cases of the IIP group. Additionally, an internal exposure of the root fragment was observed in one case in another study.
Implant survival rate
Implant survival rate was 0.968 (95% CI: 0.996, I2 = 0%) for each group.
Publication bias and TSA
The Egger and Begg tests demonstrated no publication bias for all groups, except BPH 12 months and PES 3 months groups, in which due to inadequate observation, the publication bias could not be evaluated quantitatively [Table S4]. The nonparametric trim-and-fill test declared that there were possible one and two unpublished articles for PES 3 month and ISQ, respectively [Table S5, Figure S3].
The information size boundary was surpassed by the Z-curve indicating that the pooled sample sizes of included clinical trials are sufficient to consider the outcome of MA conclusive for BPH 6 month and 12 month. Additionally, Z-curve did touch neither the information size boundary nor futility or monitoring boundaries for BPW 3 month, PES immediately, 6 month, and 12 month, and ISQ, demonstrating the pieces of evidence were inconclusive. For BPH 3 month, BPW 6 month, and PES 3 month, the information size boundary was not touched by Z-curve but the monitoring boundary was touched; therefore, it is most likely that the assumed effect is feasible [Figure 3].
|Figure 3 Trial sequential analysis diagram for (a) 3 month BPH, (b) 6 months BPH, (c) 12 months BPH, (d) 3 months BPW, (e) 6 months BPW, (f) Immediate ISQ, (g) immediate PES, (h) 3 months PES, (i) 6 months PES, and (j) 12 months PES. Cumulative Z-curve (blue line), traditional boundary (red horizontal line), the information size (red vertical line), sequential monitoring boundary (outer curved red line), and futility boundary (inner curved red line).|
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| Discussion|| |
Interpretation of main findings
The results of this meta-analysis revealed that there was no significant difference in changes in BPW between SST and conventional IIP 3 months after implantation. However, it was found that by 6 months and 12 months after IIP, SST results in fewer changes in BPH. Significantly lower resorption was detected in BPH in IIP with SST compared to conventional IIP in regard to all-time points.
Two IIP techniques were also compared based on PES, which revealed no significant difference at the time of placement. Instead, a statistically significant difference was found between IIP with and without SST in PES in favor of the SST group at 3, 6, and 12-month time points. However, no significant difference was found in comparing implant stability between IIP with or without SST at different time points.,,
Implication of findings
The present systematic review showed that IIP with SST results in better outcomes in regard to buccal bone dimensional changes and PES than conventional IIP protocol. Few studies report the height and thickness of the root fragment., Also, the position of the root fragment in regard to the bone crest is under discussion, as in some studies it is suggested to be at the level of the buccal bone plate to prevent shield exposure while others place the root 1 mm above the alveolar ridge to maintain more amount of supracrestal marginal gingival fibers which has a better effect on soft tissue stability.
One of the most controversial aspects of IIP has always been the need of placing bone graft materials in gaps between the implant surface and socket walls. Hurzeler et al. suggested filling the jumping distance of ≥2 mm between implant and root fragment with heterogeneous graft material with the aim of preventing soft tissue migration into the gap. While in other studies, in which the mentioned gap was left ungrafted for spontaneous healing, complete bone fill was achieved after the second stage surgery and it was confirmed with CBCT after 6 months. Also, a study conducted by Mitsias et al. stated that a histological analysis of a fixture with SST and without grafting materials after 5 years reported a bone–implant contact of 76.2% with noninfiltrated connective tissue in the most coronal threads between the implant and the shield. Due to the lack of sufficient long-term studies comparing SST with or without grafting material, the result of filling the jumping gap remains unclear.
In regard to patient-reported clinical outcomes such as pain, swelling, and infection, no significant differences were reported in studies analyzed in this systematic review for IIP with or without SST.
Agreements and disagreements with previous systematic reviews
In regard to the changes in width and height of buccal bone, the results of the present study were in line with a recent study published by Atieh et al., which was a meta-analysis of seven RCTs shared with this article. The results of the study showed a significant difference in this outcome in favor of SST. Esthetic outcomes of IIP with SST were reported in a systematic review by Atieh et al. They reported a better PES score for the SST group at 3, 6, and 12 months postsurgery. In the present study, the same results were obtained except for the PES score at the time of implant placement which showed no significant difference between SST and conventional protocol. Also, in a meta-analysis by Bohórquez et al., high mean PES was reported for SST which is concluded to be a result of lower volumetric changes in soft tissues and reduced marginal bone loss around implants in SST.
With regard to complication and clinical evaluation of SST, the meta-analysis by Atieh et al. demonstrates no significant difference between SST and the control group; which is similar to the current study. Another literature review by Blaschke and Schwass reported three cases with resorption of root fragment, two cases with loss of osseointegration, 13 with internal shield exposure and four with external shield exposure, and three cases with infected socket shields. The main reason for shield exposure was concluded to be the failure of soft tissue closure and the insufficient amount of shield reduction which is better to be shortened at the level of bone.
According to the results of a review by Mourya et al., a thickness of 0.5 to 1.5 mm for the root fragment was proposed to have successful results with the better esthetic outcome and reduced crestal bone resorption. Another systematic review published by Gharpure and Bhatavadekar on this topic reported a total of 24.26% of complications and adverse effects for implants with SST. The most rated complication was buccal/crestal bone loss around implants with a 78.78% distribution rate. It was concluded that a risk of infection may be possible for implants in close proximity to root fragment. Therefore, the implants may be compromised by either resorption or extraction of the infected root fragment.
The implant failure rate reported in the present study showed no significant difference between the two groups, similar to the study of Atieh et al., and was 100% in all RCTs except for 95% in both groups of one study. The systematic review of Bohórquez et al. also reported a low implant failure rate of 1.37%, and a published systematic review and meta-analysis by Ogawa et al. reported 90.5% implant survival and a low failure rate.
Limitations and suggestions
The considerable heterogeneity in the meta-analysis might be due to: not achieving complete consistency with the implant system, implant site, the difference in reference points for the measurement of width and height of buccal bone, the difference in characteristics of root fragment and its preparation, and short-term follow-ups in included studies. Additionally, the quality of included studies, the lack of double-blinding in all studies, and no single blinding and allocation concealment in most of the studies, might be considered possible limitations for this meta-analysis. In future studies, well-designed, large randomized clinical trials with long-term follow-ups should take into account to compare the clinical variables in socket-shield preparations.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]