Several techniques and modifications have been proposed in implant dentistry throughout the past years to develop faster, less invasive, and more esthetic approaches during the placement of implants. One of these innovations was placing an implant immediately after tooth extraction, eliminating the need for 4 to 6 months postextraction healing and remodeling period.1 Immediate implant placement has proven to be a highly successful approach and includes several advantages in comparison with conventional technique of implant placement, such as reduction in the number of surgical procedures, improved implant orientation during placement due to clear visualization of the extraction socket borders, preservation of the remaining alveolar bone dimensions, and improved esthetics by stabilizing the surrounding soft tissues.2–4 On the other hand, the morphology of the site, the presence of periapical pathology, the absence of keratinized tissue, thin tissue biotype, and lack of complete soft tissue closure over the extraction socket have been reported to adversely affect immediately placed implants; therefore, proper case selection and careful case evaluation are mandatory to achieve successful end results.5–7 Another main challenge that remains unresolved is that when an implant is placed immediately in the socket, a space is always present in the area surrounding the coronal portion of the implant, which is called “The Jumping Distance.” This space is due to the discrepancy in size and form between the extraction socket and the implant morphology, which can lead to bone resorption and consequence formation of a bony defect especially in the labial area.8 Therefore, surgical techniques including the use of bone grafting materials as well as using different barriers to fill the space around the implants were proposed to maintain hard and soft tissue architecture and to regenerate lost bone in areas of where bony defects occurred.9 On the other hand, some available data have shown good results in cases where the use of any type of reconstructive methods alongside immediate implants was not used.10–12 Due to this discrepancy in reported results, comparing all available data related to this issue and observing hard and soft tissue dimension stability outcomes will aid the surgeon in proper treatment planning and improved esthetic and functional results. Therefore, the aim of this study report is to systematically review the literature on immediate implant placement associated with different bone reconstructive methods using bone grafts and/or barriers to fill the space between remaining alveolar bone and the immediately placed implant on bone and soft tissue stability.
A systematic review focusing on the effect of bone graft and/or guided bone regeneration performed concurrently with immediate implant placement on the dimensional changes of bone and soft tissues. Consolidated Standards of Reporting Trials (CONSORT) and Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statements checklist were followed.13
A protocol was specified and registered with the International Prospective Register of Systematic Reviews (PROSPERO) on June 2016 (registration number CRD 42016042257), and is available from:
Eligibility Criteria for Study Inclusion
Randomized clinical trials (RCT), controlled clinical trials (CT), cross-sectional (CS), and cohort studies (C) were eligible for inclusion. Population was composed of healthy adult subjects treated with immediate implants with or without simultaneous application of bone graft and/or barrier membranes. Outcomes consisted of hard and soft tissue dimensional changes.
Comprehensive search strategies were established. MEDLINE (via PubMed), EMBASE, and CENTRAL databases were searched without language restrictions from the earliest records through June 2016. The search terms were “immediate implant” and “guided bone regeneration,” “bone graft,” “autologous bone graft,” “autogenous bone graft,” “allogenic bone graft,” “xenogenic bone graft,” “alloplastic bone graft,” “synthetic bone graft,” “FDBA,” “DFDBA,” “BioOss,” “porous hydroxyapatite,” “mineralized bovine bone” and “without bone graft” and “buccal bone thickness,” “bone contour,” “bone implant contact,” “soft tissue contour,” “bone height,” “bone level.”
Assessment of Validity
Two independent reviewers (H.A. and R.AL.J.) screened the titles, abstracts, and full texts that were identified. Disagreement between the reviewers was resolved through discussion and consensus was reached. Authors were contacted to resolve ambiguity and to retrieve missing data from the trials. Cohen's Kappa score was used to assess interreviewer agreement of selection process.14 The reasons for excluding studies were recorded Figure 1. Studies meeting the inclusion criteria underwent data extraction and validity assessment.
Predesigned extraction forms were developed to assess the following data: author name(s), publication year and place, source of funding, conflict of interest, study design, sample size, follow-up period, source, selection and description of the study population (including age, gender, race and ethnicity, teeth to be treated, and baseline measurements), surgical details of the intervention and control, measurement of outcomes, results and their variation, and risk of bias.
Data synthesis was performed through organizing data in an evidence table and a descriptive summary was created to determine study characteristics (Table 1). Descriptive statistical analysis according to the mean values was used to evaluate the outcomes of test and control groups (Tables 2–4).
Quality Assessment and Risk of Bias
The methodological quality of the included studies was assessed and recorded in Table 5 according to PRISMA.15
The screening process is shown in Figure 1. Electronic searches yielded 191 articles of which 18 were selected for full-text evaluation after screening their titles and abstracts. Ten articles16–25 were further excluded and reasons are listed in Figure 1. The k value for interreviewer agreement for potentially relevant articles was 0.95 for full-text article reviewing, indicating a “almost perfect” agreement between the 2 reviewers.14
Features of the Included Studies
Eight studies26–33 were included as shown in Table 1. Four of the studies compared bone grafting the buccal gap of immediate implants to the control sites, which received no bone graft,26,27,31,32 whereas another 3 studies compared guided bone regeneration to bone graft or membrane alone, or no bone graft.31–33 Three studies assessed the efficacy of different bone graft materials in immediate implants buccal gap grafting.28–30
Two hundred eight participants were included. The age of the participants ranged from 18 to 75 years with a follow-up period ranging from 5 to 12 months.
Two hundred eight sites were included in this review. Two studies included both maxillary and mandibular teeth,28,33 whereas 5 studies included maxillary teeth only.26,27,29,31,32 In regard to the type of teeth treated, 5 studies included anterior teeth and premolars.27,29,31–33 Although 2 studies included anterior teeth only,26,28 one study did not mention which teeth were treated.30
Surgical protocol and implants used
Three studies performed the surgical procedure under flapless technique,26–28 whereas the remaining 5 studies used a full thickness mucoperiosteal flap technique.29–33 Only 3 studies specified the use of tapered implant.26–28 Two studies used plasma-sprayed titanium implants,29,30 one study used sand-blasted acid-etched implants,31 and one study used turned surface titanium implants,32 whereas the other studies did not specify the implant surface characteristics.
Medications prescribed and postoperative management
One study prescribed presurgical antibiotics.27 In terms of postoperative management, 4 studies covered their patients with antibiotics and chlorhexidine gluconate mouth rinse29,31–33 and one prescribed analgesics as needed.27
Comparing bone graft (BG) to no bone graft (NBG)
Four studies have been found to compare the application of bone graft around immediate implants to no bone graft among other groups (Table 2).26,27,31,32 Chu et al26 found that the use of small particle bone allograft preserved the soft tissue height when compared to no bone graft sites measuring 2.72 versus 2.29 mm (P < 0.05) and preserved soft tissue thickness of 2.90 mm compared to 2.28 mm, respectively (P < 0.008). Tarnow et al27 reported higher mean facial-palatal ridge dimension, when measured on the stone casts taken at least 6 months post implant insertion, in the small particle allograft group when compared to no bone graft group measuring 10.2 versus 9.3 mm (P < 0.05). Chen et al31 used anorganic bovine xenograft in comparison with no bone graft and found no significant difference at 6 months in the vertical distance between the implant shoulder and the base of the defect (VDH), the horizontal distance between the implant shoulder and the internal socket wall (HDD), or in changes of the vertical distance from implant shoulder to bone crest (SBC). While less changes were found in the buccal bone distance to the implant shoulder (BBD) for the bone graft group (0.4 ± 0.5 mm) when compared to no bone graft group (1.1 ± 0.3 mm), P = 0.020. On the other hand, Chen et al32 compared autogenous bone graft to control sites (no bone graft) and reported no significant difference in dimensional changes of the horizontal buccal defect width (HDW), the buccal plate resorption (BPR), VDH, or HDD at the 6-months follow-up.
The studies that performed GBR
Three studies were identified (Table 3).31–33 Chen et al 2007 compared mineralized bovine xenograft alone to that with a resorbable membrane, or the control sites, which received no bone graft or a membrane, showing no significant difference between the groups in VDH, SBC, or HDD. The only difference was a significant loss of the BBD for the control group measuring 1.1 ± 0.3 mm when compared to the bone graft 0.4 ± 0.5 mm and the bone graft + membrane group 0.6 ± 0.7 mm (P = 0.020), whereas the difference was insignificant between the bone graft group and the bone graft + membrane group.31 Another study by Chen et al 2005 compared the use of nonresorbable membrane, resorbable membrane, resorbable membrane with autogenous bone, autogenous bone alone, and no graft (control) and found the difference insignificant between the techniques in VDH or HDD, whereas significant percentage reduction in the horizontal defect width (HDW) was noted for the membrane groups with or without bone graft (67.3%, 60.6%, 71.2%) compared to autogenous bone alone (34.1%) (P < 0.01), while the dissimilarity between the membranes or the use of autogenous bone alongside the membrane made no significance (P > 0.01). For the labial plate resorption (BPR), the use of nonresorbable membrane (22.9%) or autogenous bone alone (39.1%) yielded the least percentage resorption compared to resorbable membrane (60.6%) or resorbable membrane with autogenous bone (64.1%) (P < 0.01).32 Cornelini et al 2004 also compared the use of mineralized bovine xenograft with resorbable membrane to resorbable membrane alone and no significant difference was found in regard to VDH, HDD, or BPR. Although the mineralized bovine xenograft with resorbable membrane group appeared to preserve soft tissue contours in a position coronal to the implant shoulder interproximally, lingually, and labially by 2.6, 2.3, and 2.1 mm, respectively, when compared to resorbable membrane alone 1.3, 1.1, and 0.9 mm (P < 0.01, P < 0.01, P < 0.05).33
Comparison between the different types of bone grafts:
Three studies compared different types of bone grafts used to fill the defect buccal to immediately placed implants (Table 4).28–30 Viswambaran et al 2012 compared demineralized freeze-dried bone allograft (DFDBA) to hydroxyapatite (HA) and found no significant difference between the two bone graft materials in radiographic bone loss up to 12 months after implant placement.28 Hassan29 found a significant difference between the use of autogenous bone with polylactic polyglycolic acid polymer alloplast when compared to autogenous bone alone favoring the former group in residual vertical defect depth around the implant (VDH) measuring 5.0 ± 0.04 versus 5.3 ± 0.04 mm at 9 months respectively (P = 0.01), whereas reduction of the horizontal defect (HDD) was unaffected by the type of bone graft used. Another study by Hassan et al30 found that autogenous graft had 0.46 mm less marginal bone loss than polylactic polyglycolic acid polymer alloplast at 12 months, 2.54 ± 0.24 versus 3.0 ± 0.26 mm, respectively (P = 0.000).
Risk of bias assessment
The results of the bias assessment of the included studies are presented in Table 5. None of the studies obtained the highest score in the quality analysis. Randomization was performed in 3 studies; however, none of these studies specified randomization type.31–33 None of the studies performed any blinding method. In terms of selective outcome reporting, ridge dimension measurements were not fully reported in one of the studies.27 Another study did not report VDH nor HDD in the 3-month follow-up visit,29 whereas a third study did not clearly report some clinical parameters after the intervention.28 Three studies reported similarity among all groups,29,31,33 and 4 studies clearly reported control of confounding factors.13,29,31–33 None of the studies reported adherence to the CONSORT statement recommendations.13 These findings can bring included studies to uncertain risk of bias.34
The present review was conducted to evaluate the outcomes of different bone reconstructive methods, using bone grafts and/or barriers, to fill the space between remaining alveolar socket and the immediately placed implant, on bone and soft tissue stability. To authors' knowledge, this is the first systematic review conducted to evaluate those outcomes. Eighteen potential trials were identified, but data from 8 studies were eligible for analysis.26–33 After full-text selection stage, these included trials were further divided into 3 broad groups, due to variability in comparison with groups and outcomes measured, as the following: (1) Studies comparing bone grating application to no bone grafting26,27,31,32; (2) Studies that utilized guided bone regeneration31–33; and (3) Studies comparing different types of bone graft materials.28–30
All the studies in the first group have relatively similar design and follow-up period and all had control groups, which make them valid for comparison; however, in terms of surgical technique, variations were noticed.26,27,31,32 Three of those demonstrated significant advantages for the use of bone graft when compared to no bone graft in preserving soft tissue height and thickness,26 buccal-palatal horizontal ridge's dimensions,27 and buccal bone thickness.31 It should be noted that although the types of bone grafts were different in these trials, the mean gain was similar, which was less than 1 mm and no more than 0.4 mm. The clinical significance in light of the additional cost and time involved in the bone grafting procedure is left to the operator to decide. Additionally, these results are at no agreement with a systematic review by Chen and Buser35 that concluded the absence of a bony plate buccal to immediately placed implants on CBCT in 36% to 57% of the cases when bone graft was used. The last trial that used autogenous graft demonstrated no additional benefit of preserving the socket dimensions around immediate implants.32 This is likely due to the large initial defect size utilized in the study's sample (9 mm), which made it difficult to detect any significance between the groups.32 In addition, this is not in agreement with the well-known paradigm in regeneration that considers the use of autogenous bone as the golden standard.36 It should also be noted that one of the trials performed flapless extraction and implant placement which could be an important factor that aided in bone preservation due to the intact periosteum.26
The second group included 3 trials, which have similarity in terms of follow-up periods (6 months). However, variation in terms of study design, surgical techniques, sample sizes, and the presence of control groups was noted.31–33 One trial showed that the use of bone graft material with or without a membrane significantly reduced the resorption of the bony plate buccal to the immediately placed implant by half to that when no bone graft was used.31 Another trials showed significant reduction in horizontal defect width (HDW) around the implant when a membrane was used despite the type of membrane or the addition of bone graft.32 Also, it was found that nonresorbable membrane specifically aided in labial plate preservation.32 Lastly, the combination of resorbable membrane and bone graft would significantly maintain the overall soft tissue dimensions when compared to placing a resorbable membrane alone.33 Findings of these trials revealed the advantage of using a membrane and/or bone graft material for guided bone regeneration, epithelial exclusion, and space maintenance until bone regeneration occurs. But, due to the variety of results, it is unclear which augmentation technique would give superior outcomes. These results are inconsistent with a previously published systematic review stating that augmentation procedure has unclear added benefit to immediately placed implant.37
The third group composed of the final 3 trials, which compared various types of bone grafts.28–30 One trial showed that cortical autogenous bone graft significantly decreased marginal bone loss when compared to synthetic bioabsorbable polylactic polyglycolic acid polymer grafting material.30 In a later trial by the same author, the combination of previously mentioned materials was shown to be superior to autogenous bone graft alone in resolution of the vertical bony defect around the immediately placed implant,29 whereas another study found no difference between the use of demineralized freeze-dried bone allograft or hydroxyapatite on radiographic bone loss.28–30 These findings are in agreement with previously published review stating the lack of difference between the different bone augmentation materials used but that highlighted the importance of accompanying the immediately placed implant with a bone graft material to fill the jumping gap when more than 2 mm.38
It is crucial to mention that although present systematic review had a more focused different question and primary outcomes than previously published systematic reviews,35,37 the heterogeneity between included studies was still present. Therefore, quantitative analysis for outcomes was not possible. These methodological variations are not uncommon in the dental implantology literature, and it is recommended that clinicians seek advice from statisticians and research scientists in designing and analyzing studies. In addition, sample size was considered relatively small in 5 of the included studies.26,27,29,30,33 It is therefore likely that many of the studies were underpowered to demonstrate any significance difference in outcome measures between the groups.26,27,29,30,33 Nevertheless, these included studies did provide useful information, which should be carefully evaluated when deciding whether to perform augmentation procedure at the time of immediate implant placement and to evaluate what type of augmentation procedure should be utilized. A time span was devoted to contact included studies' authors to verify some information. Fortunately, one has kindly provided useful unpublished information.26 Recommendations for future trials include increasing the sample size, decreasing the number of treatment variables, and constructing proper control groups.
In the present review, several conclusions can be withdrawn as follows:
- Bone grafting of the buccal gap simultaneously with immediate implant placement resulted in preserving hard and soft tissue dimensions.
- The application of guided bone regeneration techniques aids in soft tissue preservation and prevents resorption of the buccal plate of the immediately placed implant, despite the type of membrane used.
- It is unclear whether bone graft alone, the use of membrane alone, or a combination of, would lead to the most stable hard and soft tissue profiles around immediate implants.
- In terms of comparing different bone grafting materials, autogenous bone graft showed to be superior to synthetic polylactic polyglycolic acid polymer alloplast. On the other hand, combination of autogenous bone with polylactic polyglycolic acid polymer alloplast further improved the vertical defect fill.
- Further long-term randomized clinical trials conducted under the focus of evaluating the efficiency of bone grafting materials, evaluating the effect of using a barrier, and comparing different materials used with the presence of homogenous samples and proper control are needed to confirm these conclusions.
The authors claim to have no financial interest, either directly or indirectly, in the products or information listed in the article.
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