Post-extraction dimensional changes: A systematic review and meta-analysis

A multi-centre randomized controlled trial comparing connective tissue graft with collagen matrix to increase soft tissue thickness at the buccal aspect of single implants: 1-year results

AIM

To compare connective tissue graft (CTG) with collagen matrix (CMX) in terms of increase in buccal soft tissue profile (BSP) at 1 year when applied at single implant sites.

MATERIALS AND METHODS

Patients with a single tooth gap in the anterior maxilla and horizontal mucosa defect were enrolled in a multi-centre RCT. All sites had a bucco-palatal bone dimension of at least 6 mm, received a single implant and an immediate implant restoration using a full digital workflow. Sites were randomly allocated to the control (CTG) or test group (CMX) to increase buccal soft tissue thickness. The primary outcome was the increase in BSP at 1 year when compared to the pre-operative situation based on superimposed digital surface models. The changes in BSP over time were registered at a buccal area of interest reaching from 0.5 mm below the soft tissue margin to 4 mm more apical. Secondary outcomes included patient-reported, clinical and aesthetic outcomes.

RESULTS

Thirty patients were included per group (control: 50% females, mean age 50.1; test: 53% females, mean age 48.2). The increase in BSP at 1 year was 0.98 mm (98.3% CI: 0.75 - 1.20) for CTG and 0.57 mm (98.3% CI: 0.34 - 0.79) for CMX. The mean difference of 0.41 mm (98.3% CI: 0.12 - 0.69) in favour of CTG was significant (p < 0.001). Based on an arbitrarily chosen threshold for success of 0.75 mm increase in BSP, 89.7% of the patients in the control group and 10% of the patients in the test group were successfully treated (OR = 77.90; 95% CI 13.52 - 448.80; p < 0.001). Sites treated with CMX demonstrated 0.89 mm (98.3% CI: 0.49 - 1.30) more shrinkage between postop and 1 year than sites treated with CTG. In addition, CMX resulted in significantly more marginal bone loss (0.39 mm; 95% CI 0.05- 0.74; p = 0.026) than CTG. There were no significant differences between the groups in terms of patients' aesthetic satisfaction (p = 0.938), probing depth (p = 0.917), plaque (p = 0.354), bleeding on probing (p = 0.783), midfacial recession (p = 0.915), Pink Esthetic Score (p = 0.121) and Mucosal Scarring Index (p = 0.965).

CONCLUSION

CTG remains the gold standard to increase soft tissue thickness at implant sites. Clinicians need to outweigh the benefits of CMX against considerable resorption of the graft.

Decoronation-induced infected alveolar socket defect rat model for ridge preservation

Current rat alveolar ridge preservation models have not been well standardized. In this study, we proposed decoronation-induced infected alveolar socket model of rat. The bilateral maxillary first molars (M1) of twenty-four rats were decoronized or extracted. After 2, 6, 10, and 14 weeks, bone and soft tissue changes at M1 and periodontal conditions of maxillary second (M2) and third molars (M3) were evaluated by micro-computed tomography and histological analysis. Additional eighteen rats with standardized size defects were grafted with Bio-Oss Collagen to compare with unmanipulated contralateral side. Decoronation preserved greater bone and soft tissue dimensions at M1, provided larger three-dimensional (3D) bone contour volume, but also promoted periodontal breakdown of M2 Histological results showed intense inflammatory cell infiltrations and severe bone resorption within M1 socket and at mesial aspect of M2. The critical dimensions to accommodate largest standardized defect at M1 were 2.2-2.3 mm at vertical bone height and 2.8-3.2 mm at alveolar crestal width. Bio-Oss Collagen could not fully preserve buccal or palatal bone height but could be beneficial in preserving ridge width in large alveolar defects. Collectively, if periodontally-involved alveolar bone defect is preferred, we suggest extracting M1 roots 6 weeks after decoronation to allow periodontitis to occur at M2. If standardized critical dimension defect is preferred, we suggest extracting M1 roots 2 weeks after decoronation, and creating defect in the middle of M1 site with size no larger than 2.7 mm diameter to its full depth.

Comparing the histological assessment following ridge preservation using a composite bovine derived xenograft versus an alloplast hydroxyapatite-sugar cross-linked collagen matrix

BACKGROUND

This randomized controlled trial was designed to evaluate the histological wound healing and alveolar ridge dimensional changes following ridge preservation using two different xenograft/ collagen matrices.

METHODS

Fifty-four patients each with non-molar teeth that required extraction and replacement with dental implants were enrolled. Teeth extractions were completed with minimal flap reflection and were randomized to receive ridge preservation with either 90% bovine-derived xenograft granules in a 10% porcine collagen matrix (Group A) or a sponge-like matrix of 80% microparticulate hydroxyapatite alloplast graft with 20% sugar cross-linked porcine type 1 collagen (Group B). After 16 weeks of healing and at the time of implant placement, a bone core biopsy was harvested followed by dental implant placement. The primary histological outcome evaluated were percent (%) vital bone formation and connective tissue (CT)/other (fibrous tissue and marrow space). Secondary outcomes included the change in alveolar ridge width and the buccal and lingual ridge height. Statistical analysis was completed with two-sample t-test and Fisher's exact test.

RESULTS

Forty-four patients completed the study, 23 in group A and 21 in group B. Group B presented with statistically significantly (p = 0.02) more % vital bone (39.3 ± 17.8) than group A (26.8 ± 15.8). No statistically significant difference was observed for changes in alveolar ridge dimensions.

CONCLUSIONS

Group B, when used for ridge preservation, yields statistically significantly more vital bone over a 4-month healing period. Ridge dimension changes were similar between the two groups and were adequate for implant placement. This article is protected by copyright. All rights reserved.

Alveolar Ridge Preservation with Guided Bone Regeneration or Socket Seal Technique. A Randomised, Single-Blind Controlled Clinical Trial

Objectives

To compare radiographic bone changes, following alveolar ridge preservation (ARP) using Guided Bone Regeneration (GBR), a Socket Seal (SS) technique or unassisted socket healing (Control).

Material and methods

Patients requiring a single rooted tooth extraction in the anterior maxilla, were randomly allocated into: GBR, SS and Control groups (n= 14/). Cone Beam Computed Tomography (CBCT) images were recorded post‐extraction and at 4 months, the mid‐buccal and mid‐palatal alveolar ridge heights (BARH/PARH) were measured. The alveolar ridge width, cross‐sectional socket and alveolar‐process area changes, implant placement feasibility, requirement for bone augmentation and post‐surgical complications were also recorded.

Results

BARH and PARH was found to increase with the SS (0.65 mm ± 1.1/0.65 mm ± 1.42) techniques, stabilise with GBR (0.07 mm ± 0.83/0.86 mm ±1.37) and decrease in the Control (−0.52 mm ± 0.8/−0.43 mm ± 0.83). Statistically significance was found when comparing the GBR and SS BARH (p = .04/.005) and GBR PARH (p = .02) against the Control. GBR recorded the smallest reduction in alveolar ridge width (−2.17 mm ± 0.84), when compared to the Control (−2.3 mm ± 1.11) (p = .89). A mid‐socket cross‐sectional area reduction of 4% (−2.27 mm² ± 11.89), 1% (−0.88 mm² ± 15.48) and 13% (−6.93 mm² ± 8.22) was found with GBR, SS and Control groups (GBR vs. Control p = .01). The equivalent alveolar process area reduction was 8% (−7.36 mm² ± 10.45), 6% (−7 mm² ± 18.97) and 11% (−11.32 mm² ± 10.92). All groups supported implant placement, with bone dehiscence noted in 57% (n = 4), 64%(n = 7) and 85%(n = 12) of GBR, SS and Control cases (GBR vs. Control p = .03). GBR had a higher risk of swelling and mucosal colour change, with SS associated with graft sequestration and matrix breakdown.

Conclusion

GBR ARP was found to be more effective at reducing radiographic bone dimensional changes following tooth extraction.

Immediate implant placement with or without socket grafting: A systematic review and meta-analysis

OBJECTIVES

To assess the effect of grafting the gap (SG) between the implant surface and alveolar socket on hard and soft tissue changes following single immediate implant placement (IIP).

MATERIALS AND METHODS

Two independent reviewers conducted an electronic literature search in Pubmed, Web of Science, Embase and Cochrane databases as well as a manual search to identify eligible clinical studies up to August 2021. Randomized controlled trials (RCTs) comparing IIP with and without SG were included for a qualitative analysis. Meta-analyses were performed when possible.

RESULTS

Out of 3627 records, 15 RCTs were selected and reported on 577 patients who received 604 single immediate implants (IIP + SG: 298 implants in 292 patients; IIP: 306 implants in 285 patients) with a mean follow-up ranging from 4 to 36 months. Two RCTs showed low risk of bias. Meta-analysis revealed 0.59 mm (95% CI [0.41; 0.78], p < 0.001) or 54% less horizontal buccal bone resorption following IIP + SG when compared to IIP alone. In addition, 0.58 mm (95% CI [0.28; 0.88], p < 0.001) less apical migration of the midfacial soft tissue level was found when immediate implants were installed with SG. A trend towards less distal papillary recession was found (MD 0.60 mm, 95% CI [-0.08; 1.28], p = 0.080) when SG was performed, while mesial papillae appeared not significantly affected by SG. Vertical buccal bone changes were also not significantly affected by SG. Insufficient data were available for meta-analyses on horizontal midfacial soft tissue changes, pink esthetic score, marginal bone level changes, probing depth and bleeding on probing. Based on GRADE guidelines, a moderate recommendation for SG following IIP can be made.

CONCLUSION

SG may contribute to horizontal bone preservation and soft tissue stability at the midfacial aspect of immediate implants. Therefore, SG should be considered as an adjunct to IIP in clinical practice.

Alveolar ridge preservation reduces the need for ancillary bone augmentation in the context of implant therapy

Background

There is limited information on the need for bone augmentation in the context of delayed implant placement whether alveolar ridge preservation (ARP) is previously performed or not. The primary aim of this retrospective cohort study was to evaluate the efficacy of ARP therapy after tooth extraction compared with unassisted socket healing (USH) in reducing the need for ancillary bone augmentation before or at the time of implant placement.

Methods

Adult subjects that underwent non‐molar single tooth extraction with or without simultaneous ARP therapy were included in this study. Cone beam computed tomography scans obtained before tooth extraction and after a variable healing period were used to record the baseline facial bone thickness and to virtually plan implant placement according to a standard method. A logistic regression model was used to evaluate the effect of facial alveolar bone thickness upon tooth extraction and baseline therapy (USH or ARP) on the need for additional bone augmentation, adjusting for several covariates (i.e., age, sex, baseline KMW, and tooth type).

Results

One hundred and forty subjects that were equally distributed between both baseline therapy groups constituted the study population. Implant placement was deemed virtually feasible in all study sites. Simultaneous bone augmentation was considered necessary in 60% and 11.4% of the sites in the USH and ARP group, respectively. Most of these sites (64.2% in the USH group and 87.5% in the ARP group) exhibited a thin facial bone phenotype (<1 mm) at baseline. Logistic regression revealed that the odds of not needing ancillary bone augmentation were 17.8 times higher in sites that received ARP therapy. Furthermore, the need for additional bone augmentation was reduced 7.7 times for every 1 mm increase in facial bone thickness, regardless of baseline therapy.

Conclusions

Based on a digital analysis, ARP therapy, compared with USH, and thick facial alveolar bone largely reduce the need for ancillary bone augmentation at the time of implant placement in non‐molar sites.

Dimensional Changes in the Alveolus after a Combination of Immediate Postextraction Implant and Connective Grafting and/or Socket Shield Technique

Immediate implant placement protocols after dental extraction have enabled a reduction in surgical phases. This procedure has increased patient satisfaction and similar survival rates to late implant placement procedures. However, placing an implant immediately after dental extraction does not counteract the physiological remodeling of alveolar bone. For this reason, additional surgical techniques have been developed, such as the placement of a connective tissue graft (CTG) or the socket shield technique (SST). Dimensional changes in the peri-implant tissues were observed after placement of immediate implants following the extraction and CTG and/or SST. A total of 26 surgical interventions were carried out in which dimensional change variables of peri-implant tissues were analyzed. The preoperative state and immediate postoperative situation were compared with the situation after one year. Measurements were taken at 3, 5, and 7 mm from the gingival margin and analyzed in this CBCT radiological study (Planmeca Promax 3D). The implant platform was used as a reference point for the measurement of changes in alveolar crest height. One year after performing either of the two techniques (CTG and/or SST), a significant increase in the gingiva thickness and vestibular cortex occurred at 5 mm (0.65 ± 1.16 mm) and 7 mm (0.95 ± 1.45 mm) from the gingival margin. Additionally, an increase in thickness of palatal bone was registered at 3 mm (0.48 ± 0.90 mm). The graft placement group showed an increase in thickness of peri-implant tissue in the vestibular area after one year, although CTG and SST groups were clinically similar. The implementation of SST revealed promising results regarding the buccal thickness of hard and soft tissues after one year. A significant increase in vestibular cortical bone thickness, as well as the overall mucosa thickness and buccal bone at 3 mm from the gingival margin, was observed. A significant reduction in the distance from the bone crest to the platform was detected in both techniques. Both techniques (CTG and SST) are appropriate to provide sufficient volume to peri-implant tissues in the vestibular area of anterior maxillary implants. Some limitations were detected, such as the lack of an aesthetic analysis or small sample size, so results should be interpreted with caution. Future studies are necessary to further evaluate the long-term predictability of these techniques.

Impact of the periodontal phenotype in premolar and molar sites on bone loss following full thickness mucoperiosteal flap. A 1-year prospective clinical trial

BACKGROUND

Full thickness mucoperiosteal flap (FTF) elevation could potentially affect the periodontium of the involved teeth; it is not clear if the periodontal phenotype of teeth involved in a FTF may influence these changes. The aim of this study was to evaluate the impact of FTF on teeth periodontium, as well as assessing the impact of periodontal phenotype on bone remodeling.

METHODS

In this single arm prospective clinical trial, 26 subjects and a total of 52 adjacent teeth were included. Patients receiving implant surgery in the posterior area, at the time of implant site preparation, an FTF was extended one tooth mesial and distal to the planned site, and the flap was elevated both facially and lingually. Vertical and horizontal bone linear changes were measured on both adjacent teeth, using superimposed cone-beam computerized tomography (CBCT) images taken prior to implant placement (T0) and at 12 months (T1). Baseline digital scans of models and DICOM files were superimposed to assess the periodontal phenotype.

RESULTS

Vertical bone changes from T0 to T1 were statistically significant (p = 0.013), with changes were significantly higher at the mesial (-0.31± 0.30 mm) and facial (p<0.05) sites. Horizontal dimensional changes 5 mm subcrestally were similar among different locations (p = 0.086) and the bone width loss was higher closest to the crest (p = 0.001). No correlation was found between soft tissue thickness and bone changes. However, bone thickness at baseline appears to influence the extent of horizontal bone remodeling. Overall, the magnitude of bone loss either vertically or horizontally was clinically insignificant (≤0.4 mm).

CONCLUSION(S)

Marginal bone changes in maxillary and mandibular posterior teeth following FTF at 12 months are very minimal, and mainly influenced by bone rather than soft tissue thickness. Overall, FTF does not seem to have deleterious effects on adjacent teeth periodontium. This article is protected by copyright. All rights reserved.

Low-dose CBCT imaging of alveolar buccal bone adjacent to mandibular anterior teeth- a pilot study

Objectives

Accurate description of buccal bone adjacent to mandibular anterior teeth is helpful for planning and monitoring periodontal and orthodontic treatment. Low-dose cone beam computed tomography (LD-CBCT) imaging has shown promising results for very small dental structures in animals. This study asserts that LD-CBCT is sufficiently accurate to measure buccal alveolar bone adjacent to human mandibular anterior teeth.

Materials and methods

Buccal bone level adjacent to 16 mandibular anterior teeth from four human cadavers was measured radiographically using one high-dose (HD) CBCT protocol and two LD-CBCT protocols. The resulting radiographic measurements of buccal bone height (bl) and thickness (bt) were compared with reference probe and reflected-light microscopy measurements. Measurement medians and Bland–Altman plots were calculated, and a linear mixed model was used to compare raters and imaging modalities.

Results

All regression coefficients were approximately 0, indicating high interrater, intrarater, and intermodality agreement. No significant differences were found between reference measurements and CBCT protocols. The mean differences for bl measurements were 0.07 mm (rater 1 [r1]) and 0.12 mm (rater 2 [r2]) for HD-CBCT; 0.07 mm (r1) and 0.13 mm (r2) for LD-CBCT-1; and 0.02 mm (r1) and 0.01 mm (r2) for LD-CBCT-2. For bt measurements, mean differences were 0.02 mm (r1) and 0.02 mm (r2) for HD-CBCT; 0.01 mm (r1) and 0.01 mm (r2) for LD-CBCT-1; and 0.00 mm (r1) and 0.01 mm (r2) for LD-CBCT-2.

Conclusions

Within the limitations of the present study, LD-CBCT seems to be a precise method for describing buccal bone and its thickness adjacent to mandibular anterior teeth in this experimental setting.

Clinical relevance

For the first time, this study showed LD-CBCT produces excellent results and is a reliable modality for imaging buccal bone in vitro. If clinical studies confirm these results, LD-CBCT could enable better treatment planning and monitoring at a radiation dose that is far lower than that of conventional HD-CBCT but similar to that of panoramic views.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00784-022-04389-x.

Pontic site development for fixed dental prostheses with and without soft tissue grafting: 1-year results of a cohort study

AIM

To describe and compare the pontic site development for fixed-dental prostheses (FDPs) with and without soft tissue grafting up to one-year post insertion of FDPs.

MATERIALS AND METHODS

A convenience sample of 24 patients participating in an ongoing RCT was provided with three-unit tooth-borne FDPs. Six patients received a subepithelial connective tissue graft (SCTG) at the pontic site, whereas 18 patients were treated without any soft tissue graft (CONTROL). Digital impressions were taken prior to tooth preparation, after tooth preparation, after insertion of the final FDP, and at the 1 year of follow-up. The obtained stereolithography files (STL) were superimposed and profilometric as well as linear changes of the soft tissue profile were assessed at the pontic regions. Profilometric outcomes included changes of the ridge contour, the alveolar ridge width, and the crown height of the pontic. Further outcomes assessed included: the papilla index, the pink esthetic score (PES), probing depth (PD), bleeding on probing (BOP), and plaque control record (PCR). Descriptive and nonparametric statistics were applied for all outcome measures.

RESULTS

The median profilometric contour between tooth preparation and 1 year after the insertion of the final FDP decreased by - 0.25 mm [Q1, Q3: - 0.36, 0.14] in the CONTROL group and increased by 0.61 mm [Q1, Q3: - 0.18, 1.06] in the SCTG group (intergroup p = 0.038). The alveolar ridge width between prior to tooth preparation and the one-year follow-up amounted to - 0.12 mm [Q1, Q3: - 0.74, 0.70] (= loss) in the CONTROL group and to 2.23 mm [Q1, Q3: 0.62, 3.86] (= gain) in the SCTG group (intergroup p = 0.032). At one year, the median crown height of the pontic tended to decrease by - 1.24 mm [Q1, Q3: - 2.05, - 1.05] in the SCTG group (intragroup p = 0.094) and by - 0.22 mm [Q1, Q3: - 0.58, 0.66] in the CONTROL group (intragroup p = 0.831), with significant differences between the groups (intergroup p = 0.022). The papilla index between prior to tooth preparation and one year of follow-up improved significantly in both groups (p < 0.05). Between FDP delivery and one year of follow-up, the PES values decreased significantly in the CONTROL group (intragroup p = 0.007), while in the SCTG group the change was not significant (intragroup p = 0.875). Clinical parameters (PD, BOP, and PCR) remained stable over time and did not differ between the groups at any time point (intergroup p > 0.05).

CONCLUSION

Within the limitations of the present study, soft tissue grafting tends to limit contour changes at pontic sites, thus maintaining the esthetic outcomes over time. The lack of soft tissue grafting results in stable clinical outcomes; however, it may lead to a decrease in aesthetic outcomes over time.

CLINICAL RELEVANCE

Autogenous soft tissue grafting seems to be a valid therapeutic option for the development of the pontic site to restore ridge defects prior to the delivery of fixed dental prostheses and to limit dimensional changes over time.

A randomized controlled trial evaluating hyaluronic acid gel as wound healing agent in alveolar ridge preservation

AIM

To compare the results of administration of hyaluronic acid (HA) gel to no gel administration following alveolar ridge preservation (ARP) in terms of changes in wound dimensions over time.

MATERIALS AND METHODS

Systemically healthy patients scheduled for ARP at one or two sites in the incisor, cuspid, or premolar area with at least one neighbouring tooth and >50% buccal bone present following extraction were included. ARP consisted of socket grafting with collagen-enriched, deproteinized bovine bone mineral and socket sealing by means of a collagen matrix. Following surgical therapy, sites were randomly allocated to the control group (no gel application) or the test group (0.8% HA gel applied onto the collagen matrix three times per day for 7 days). Bucco-lingual and mesio-distal wound dimensions were registered at T0 (immediately post operation), T1 (1 week), and T2 (3 weeks). Patient-reported outcomes, clinical outcomes, and hard and soft tissue changes were recorded up to 4 months (T3).

RESULTS

In the control group, 20 patients (7 males, 13 females; mean age 53.30) with 23 sites, and in the test group 18 patients (9 males, 9 females; mean age 52.56) with 23 sites, were included. There were no significant differences between the groups in the changes in wound dimensions from T0 to T2 (bucco-lingual aspect: p = .340; mesio-distal aspect: p = .883). Three sites (13%) in the control group and six (26%) in the test group demonstrated complete wound resolution at T2 (p = .259). HA failed to show any effect on the number of analgesics taken (p = .175), patient-reported outcomes (p ≥ .263), alveolitis (p = .136), socket healing (p ≥ .424), soft tissue changes (p ≥ .064), or mucosal scarring (p = .548). However, significantly more horizontal bone loss at the coronal aspect was found in the test group (p ≤ .025).

CONCLUSION

HA failed to promote wound resolution on a collagen matrix. This study was registered in ClinicalTrials.gov (NCT04467736).

Survival rates of ultra-short (<6 mm) compared with short locking-taper implants supporting single crowns in posterior areas: A 5-year retrospective study

Background

Short and ultra‐short implants represent a predictable treatment, in terms of implant survival, with patients presenting insufficient available bone volumes. Moreover, single crown restorations represent a gold standard in terms of oral hygiene.

Purpose

The aim of this retrospective study was to evaluate implant survival, marginal bone loss, and peri‐implant complications in 333 locking‐taper short and ultra‐short implants.

Materials and Methods

Implants were placed in the maxillary and mandibular posterior regions of 142 patients. Clinical and radiographic examinations were performed at 5‐year recall appointments.

Results

All implants placed consisted of 8.0‐, 6.0‐, and 5.0‐mm length, 38.14%, 34.53%, and 27.33%, respectively. Three hundred thirty‐two implants (one early failure) were rehabilitated with single crowns in 141 patients. In 45.48% of the implants the crown‐to‐implant ratio was ≥2, with a mean value of 1.94. Overall implant‐based survival after 5 years of follow‐up was 96.10%: 96.85%, 95.65%, and 95.60% for 8.0‐, 6.0‐, and 5.0‐mm length implants, respectively (p = 0.82). Overall patient‐based survival was 91.55%. Regarding crestal bone level variations, average crestal bone loss and apical shift of the “first bone‐to‐implant contact point” position were 0.69 and 0.01 mm, respectively. Setting the threshold for excessive bone loss at 1 mm, during the time interval from loading to follow‐up, 28 implants experienced loss of supporting bone greater than 1 mm: 19 of them (67.85%) were surgically treated with a codified surgical regenerative protocol. After 60 months, a peri‐implantitis prevalence of 5.94% was reported, with an overall implant success of 94.06%: 95.93%, 92.73%, and 93.10% for 8.0‐, 6.0‐, and 5.0‐mm length implants, respectively (p = 0.55).

Conclusion

Long‐term outcomes suggest that short and ultra‐short locking‐taper implants can be successfully restored with single crowns in the posterior area of the maxilla and mandible.

Prediction of Residual Alveolar Bone Height in the Posterior Maxilla After Dental Extractions

PURPOSE

After tooth extraction in the posterior maxilla, bone resorption often limits implant placement unless additional grafting procedures are performed. However, it is difficult to predict the amount of bone that will remain after extraction based on current evidence. The purpose of this study was to develop a method for predicting the postextraction alveolar bone height in the posterior maxilla.

PATIENTS AND METHODS

The authors conducted a retrospective cohort study that included all patients who were treated for the extraction and replacement of a maxillary first molar with a dental implant from 2008 to 2019. Potential predictor variables included thirteen pre-extraction radiographic measurements obtained via cone-beam computed tomography. The outcome variable was having more than 6 mm of bone height from the alveolar crest to the sinus floor after extraction. Decision tree analyses were used to search for the best predictors of this outcome using random forest analysis with a maximum of 3 randomly chosen covariates in each candidate tree.

RESULTS

A total of 63 patients were included in the study; 55.6% were women, and the mean age was 57.6 ± 14.5 years. In this study population, having a bone height from the furcation to the maxillary sinus floor of <6.7 mm had a 7.1% chance of having >6 mm of bone height postoperatively, whereas those patients with ≥6.7 mm at the same position preoperatively had a 61.9% chance of having >6 mm of bone height postoperatively (P < .001).

CONCLUSIONS

This study suggests that patients with <6.7 mm of bone from the furcation to the sinus are at increased risk of having insufficient bone to support a dental implant without additional grafting at the maxillary first molar position. When treating these patients, the surgeon should consider performing a procedure at the time of extraction to increase bone height or explain additional bone grafting is expected for ideal implant placement.

A multi-centre randomized controlled trial comparing connective tissue graft with collagen matrix to increase soft tissue thickness at the buccal aspect of single implants: 3-month results

AIM

To compare connective tissue graft (CTG) with collagen matrix (CMX) in terms of changes over time in buccal soft tissue profile (BSP) when applied at single implant sites.

MATERIALS AND METHODS

Patients with a single tooth gap in the anterior maxilla and horizontal mucosa defect were enrolled in a multi-centre randomized controlled trial. All sites had a bucco-palatal bone dimension of at least 6 mm and received a single implant and immediate implant restoration using a full digital workflow. Sites were randomly allocated to the control (CTG) or test group (CMX: Geistlich Fibro-Gide®, Geistlich Pharma AG, Wolhusen, Switzerland) to increase buccal soft tissue thickness. Primary outcome was increase in BSP at T1 (immediately after operation) and T2 (3 months) based on superimposed digital surface models. Secondary parameters included patient-reported clinical and aesthetic outcomes.

RESULTS

Thirty patients were included per group (control: 50% females, mean age 50; test: 53% females, mean age 48). Even though surgeons applied thicker grafts when using CMX, sites treated with CMX demonstrated 0.78 mm (95% CI 0.41-1.14) more shrinkage between T1 and T2 than sites treated with CTG. The final increase in BSP was 1.15 mm (95% CI 0.88-1.43) for CTG and 0.85 mm (95% CI 0.58-1.13) for CMX. The mean difference of 0.30 mm (95% CI -0.01 to 0.61) at T2 in favour of CTG was of borderline significance (p = .054). There were no significant differences between the groups in terms of post-operative bleeding (p = .344), pain (p = .331), number of analgesics taken (p = .504), oedema (p = .227), and pink aesthetic score (p = .655). VAS for post-operative haematoma was 6.56 (95% CI 0.54-12.59) lower for CMX, and surgery time could be reduced by 9.03 min (95% CI 7.04-11.03) when applying CMX. However, CMX resulted in significantly more marginal bone loss (0.38 mm; 95% CI 0.15-0.60), deeper pockets (0.30 mm; 95% CI 0.06-0.54), and more mid-facial recession (0.75 mm; 95% CI 0.39-1.12) than CTG.

CONCLUSIONS

CTG remains the gold standard for increasing soft tissue thickness at the buccal aspect of implants.

Octacalcium Phosphate Bone Substitute (Bontree®): From Basic Research to Clinical Case Study

Bone grafts used in alveolar bone regeneration can be categorized into autografts, allografts, xenografts, and synthetic bones, depending on their origin. The purpose of this study was to evaluate the effect of a commercialized octacalcium phosphate (OCP)-based synthetic bone substitute material (Bontree®) in vitro, in vivo, and in clinical cases. Material characterization of Bontree® granules (0.5 mm and 1.0 mm) using scanning electron microscopy and X-ray diffraction showed that both 0.5 mm and 1.0 mm Bontree® granules were uniformly composed mainly of OCP. The receptor activator of NF-κB ligand (RANKL) and alkaline phosphatase (ALP) activities of MG63 cells were assessed and used to compare Bontree® with a commercial biphasic calcium phosphate ceramic (MBCP+TM). Compared with MBCP+TM, Bontree® suppressed RANKL and increased ALP activity. A rabbit tibia model used to examine the effects of granule size of Bontree® grafts showed that 1.0 mm Bontree® granules had a higher new bone formation ability than 0.5 mm Bontree® granules. Three clinical cases using Bontree® for ridge or sinus augmentation are described. All eight implants in the three patients showed a 100% success rate after 1 year of functional loading. This basic research and clinical application demonstrated the safety and efficacy of Bontree® for bone regeneration.

Early implant placement with or without alveolar ridge preservation in single tooth gaps renders similar esthetic, clinical and patient-reported outcome measures: One-year results of a randomized clinical trial

Objectives

To test whether early implant placement with alveolar ridge preservation (ARP) results in different esthetic, clinical and patient‐reported outcome measures (PROMs) compared with early implant placement without ARP.

Material and methods

Seventy‐five patients requiring single tooth extraction in the anterior maxilla were recruited. Following tooth extraction, the patients were randomly allocated to three groups: (a) ARP using demineralized bovine bone mineral containing 10% collagen (DBBM‐C) covered by a collagen matrix (CM) (n = 25), (b) ARP using DBBM‐C covered with a palatal graft (PG) (n = 25) and (c) spontaneous healing (control) (n = 25). Eight weeks after tooth extraction, a CBCT was taken and early implant placement was performed in all patients. Esthetic, clinical and PROMs were evaluated one year post‐loading.

Results

A total of 70 patients were available for re‐examination at one year post‐loading. The median mid‐facial mucosal margin change amounted to −0.02 mm (IQR −0.27–0.46) in the CM group, −0.13 mm (IQR −0.44–0.25) in the PG group and −0.14 mm (IQR −0.29–0.07) in the control group, with no significant differences between the groups. Mean PES scores amounted to 7.0 ± 1.4 in the CM group, 7.1 ± 1.5 in the PG group and 7.3 ± 1.7 in the control group without significant differences between the groups. Plaque, bleeding on probing and probing depth did not differ between treatment groups. PROMs in general revealed no significant differences between the groups.

Conclusion

Early implant placement with ARP using either a collagen matrix or a palatal graft rendered similar esthetic, clinical and PROMs to early implant placement without ARP. When a failing tooth can be replaced with an implant within 2 months after tooth extraction, the added value of ARP might be clinically negligible.

Autogenous Mineralized Dentin versus Xenograft granules in Ridge Preservation for Delayed Implantation in Post-extraction Sites: A Randomized controlled clinical trial with an 18 months follow-up

OBJECTIVES

To test primary stability of delayed implants placed in post-extraction ridges preserved with autogenous mineralized dentin matrix (MDM) versus xenograft granules. Clinical, histological and pain experience outcomes were further assessed.

MATERIAL AND METHODS

From March 2018 to July 2020, patients requiring ridge preservation in preparation for delayed implant placement in post-extraction sites were included. Participants were randomly allocated to either the test (MDM) or control group (xenograft granules) prior to ridge preservation. Visual analogue scale and analgesic consumption were measured every day for a week. Six months after preservation, trephine cores were harvested for histomorphometry prior to implant placement. Implants were then placed, and implant stability was measured immediately as well as two months after placement. Marginal bone loss and presence of mucositis/peri-implantitis were registered up to 18 months after prosthetic loading.

RESULTS

Fifty-two patients (66 implants) completed the study. MDM and xenograft groups presented similar primary (77.1 ± 6.9 versus. 77.0 versus. 5.9) and secondary (81.8 ± 5.1 versus. 80.1 ± 3.8) implant stabilities. The percentage of newly formed bone in MDM (47.3%) was significantly higher than xenograft (34.9%) (p < .001), and the proportion of residual graft was significantly lower (12.2% in MDM and 22.1% in xenograft) (p < .001). No significant differences were found as far as clinical, radiographic and patient-related outcomes.

CONCLUSIONS

Implants placed in sites preserved with MDM had similar primary stability in comparison to xenograft granules. MDM showed a significantly higher quantity of newly formed bone and lower amount of residual graft in histomorphometry results and equal clinical and patient-related outcomes.

Quantitative assessment of the jawbone quality classification: A meta-analysis study

AIM

Bone quality is evaluated using bone density for qualitative classification, a characteristic that may be delicate to evaluate. Contemporary implantology that relies on modern measurement techniques, needs a more quantitative estimate of the bone quality.

MATERIALS AND METHODS

PubMed and EMBASE databases were searched with no time restriction. Clinical and radiographic studies reporting on alveolar ridge dimensions and its parameters in different areas of the dentate and edentulous jaws were included. A meta-analysis was performed using random effect models to report a combined mean for alveolar ridge and its parameters. Meta regression statistical tests were performed in order to identify differences in those outcome parameters.

RESULTS

30 studies were included. The majority of the selected studies (total of 27) used live human subjects and CBCT to analyze alveolar ridge dimensions and its parameters. Using the combined mean obtained from the meta-analysis, a typical portrait of the alveolar ridge was constructed, and a geometrically based quantitative bone classification proposed. The quantitative classification was found to match the existing qualitative classification.

CONCLUSION

A geometry-based analysis was constructed that yields valuable insights on the bone type based on its components and on the dynamics of the dentate / edentulous states.

FasL Is Required for Osseous Healing in Extraction Sockets in Mice

Fas ligand (FasL) is a member of the tumor necrosis factor (TNF) superfamily involved in the activation of apoptosis. Assuming that apoptosis is initiated after tooth extraction it is reasonable to suggest that FasL may play a pivotal role in the healing of extraction sockets. Herein, we tested the hypothesis of whether the lack of FasL impairs the healing of extraction sockets. To this end, we extracted upper right incisors of FasL knockout (KO) mice and their wildtype (WT) littermates. After a healing period of two weeks, bone volume over total volume (BV/TV) via µCT and descriptive histological analyses were performed. µCT revealed that BV/TV in the coronal region of the socket amounted to 39.4% in WT and 21.8% in KO, with a significant difference between the groups (p=0.002). Likewise, in the middle region of the socket, BV/TV amounted to 50.3% in WT and 40.8% in KO (p<0.001). In the apical part, however, no difference was noticed. Consistently, WT mice displayed a significantly higher median trabecular thickness and a lower trabecular separation when compared to the KO group at the coronal and central region of the socket. There was the overall tendency that in both, female and male mice, FasL affects bone regeneration. Taken together, these findings suggest that FasL deficiency may reduce bone regeneration during the healing process of extraction sockets.

Effect of different platelet-rich fibrin matrices for ridge preservation in multiple tooth extractions: A split-mouth randomized controlled clinical trial

AIM

To evaluate dimensional changes in the alveolar ridge and bone structure after tooth extraction when L-PRF or A-PRF+ was used in comparison to unassisted socket healing.

MATERIALS AND METHODS

Twenty patients in need of at least three tooth extractions in the aesthetic zone were included. L-PRF, A-PRF+ or control was randomly assigned, leaving one empty socket/edentulous site between conditions. CBCT scans were obtained immediately after tooth extraction and after 3 months of healing. Horizontal and vertical dimensional changes of the ridge and socket fill were calculated. Histological and micro-CT analysis of bone biopsies were used to evaluate post-surgical bone structural healing.

RESULTS

Mean horizontal and vertical changes at 1-mm below the crest (buccal and palatal side) were similar for the three sites (p > 0.05). For the socket fill, L-PRF (85.2%) and A-PRF+ (83.8%) showed superior values than the control (67.9%). The histological and radiological analysis reported more newly formed bone for the PRF groups, without any significant differences between both.

CONCLUSIONS

PRF matrices failed to reduce the dimensional changes after multiple tooth extractions in the premaxilla. After 3-month healing, both PRF matrices showed radiographically a significant superiority for the socket fill. Histologically, they seemed to accelerate new bone formation.

A retrospective cohort study of how alveolar ridge preservation affects the need of alveolar ridge augmentation at posterior tooth implant sites

Objectives

The aim of this study was to assess whether alveolar ridge preservation (ARP) can reduce the need of ridge augmentation at posterior tooth sites.

Material and methods

This study enrolled patients who received dental implants at posterior tooth sites during 2013–2019. Demographic data and dental treatment histories were collected. Based on healing patterns after tooth extraction, patients were divided into ARP and spontaneous healing (SH) groups. Three surgical treatment plans were devised according to the alveolar bone volume on cone-beam computed tomography (CBCT). The three treatment plans were to perform implant alone, simultaneous guided bone regeneration (GBR) and implantation, and staged GBR before implantation. Statistical analyses were performed to determine relationships.

Results

There were 92 implant records in the ARP group and 249 implant records in the SH group. A significant intergroup difference was observed regarding the frequency distribution of the treatment modality of staged GBR before implant (χ² = 15.07, p = 0.0005). Based on the implant alone treatment modality and simple logistic regression, the SH pattern was related to staged GBR before implant (SH vs. ARP: crude odds ratio (OR) = 4.65, 95% confidence interval (CI) = 2.15–11.61, p = 0.0003). After adjusting confounding factors, the risk was still significant (adjusted OR = 5.02, 95% CI = 2.26–12.85, p = 0.0002).

Conclusions

The study results suggested that ARP is more likely to lead to the treatment modality of implant alone and reduce the need for staged GBR before implantation.

Clinical relevance

This study describes ARP capable of minimizing the need for staged GBR before implantation and shortening the treatment duration.