Influence of blinded wound closure on the volume stability of different GBR materials: anin vitrocone-beam computed tomographic examination

Enhancing guided bone regeneration with cross-linked collagen-conjugated xenogeneic bone blocks and membrane fixation: A preclinical in vivo study

OBJECTIVE

To determine whether combining cross-linked (CL) collagen-integrated xenogeneic bone blocks stabilized with the fixation of resorbable collagen membranes (CM) can enhance guided bone regeneration (GBR) in the overaugmented calvarial defect model.

MATERIALS AND METHODS

Four circular defects with a diameter of 8 mm were prepared in the calvarium of 13 rabbits. Defects were randomly assigned to receive one of the following treatments: (i) non-cross-linked (NCL) porcine-derived collagen-embedded bone block covered by a CM without fixation (NCL + unfix group); (ii) NCL bone block covered by CM with fixation using bone-tack (NCL + fix group); (iii) cross-linked (CL) porcine-derived collagen-embedded bone block covered by CM without fixation (CL + unfix group); and (iv) CL bone block covered by CM with fixation using bone-tack fixation (CL + fix group). The efficacy of GBR was assessed through histological and molecular analyses after 2 and 8 weeks.

RESULTS

At 2 weeks, there were no significant differences in histologically measured areas of newly formed bone among the groups. At 8 weeks, however, the CL + fix group exhibited a larger area of new bone (5.08 ± 1.09 mm2, mean ± standard deviation) compared to the NCL + unfix (1.62 ± 0.42 mm2; p < .0083), NCL + fix (3.97 ± 1.39 mm2) and CL + unfix (2.55 ± 1.04 mm2) groups. Additionally, the expression levels of tumour necrosis factor-alpha, fibroblast growth factor-2, vascular endothelial growth factor, osteocalcin and calcitonin receptor were significantly higher in the CL + fix group compared to the other three groups (p < .0083).

CONCLUSION

Cross-linked bone blocks stabilized with collagen membrane fixation can significantly enhance GBR.

Effects of hard- and/or soft-tissue grafting with early implant placement: Histomorphometric outcomes of an exploratory study in canines

OBJECTIVE

To histomorphometrically determine the effects of hard- and/or soft-tissue augmentation by applying the early implant placement protocol.

MATERIALS AND METHODS

The distal roots of the maxillary second and third premolars were extracted in 10 mongrel dogs. After 1 month, early implant placement was performed in the distal roots, resulting in buccal dehiscence defects. Four treatments were then randomly applied: (1) guided bone regeneration (GBR), (2) connective tissue grafting (CTG), (3) simultaneous GBR and CTG (GBR + CTG) and (4) no further treatment (control). Healing abutments were connected to all implants to allow non-submerged healing. At 4 and 16 weeks, tissue sections were harvested and histomorphometric analyses were performed.

RESULTS

Group GBR presented the largest total tissue thickness at 4 weeks, but underwent a greater remodelling compared with the other groups between 4 and 16 weeks. At 16 weeks, the overall tissue thickness was largest in group GBR + CTG. This group was also the most favourable in terms of the level of the margo mucosae and the presence of mineralized tissue at the coronal level. Group CTG demonstrated a stable tissue thickness over time, with a larger thickness at 16 weeks compared with group GBR.

CONCLUSION

Simultaneous CTG and GBR resulted in the most-favourable tissue thickness when applying the early implant placement protocol.

Horizontal ridge augmentation using guided bone regeneration with an association of particulate allografts mixed with platelet-rich fibrin, collagen membrane and tent-screws: A prospective study

BACKGROUND

Guided Bone Regeneration (GBR) is a versatile technique employed not only to correct pre-implant alveolar bone defects but also to facilitate bone defect correction during simultaneous implant placement. The effectiveness of GBR varies significantly among different protocols, as reported in the literature. This study specifically aimed to radiologically evaluate the horizontal bone gain obtained using a GBR procedure combining a particulate allograft, platelet-rich fibrin, resorbable collagen membrane, and screw tents.

MATERIALS AND METHODS

A total of 42 patients with an insufficient alveolar bone width for dental implant placement were treated with a GBR technique using a mixture of particulate allograft (demineralised freeze-dried bone allograft 300-500 and 500-1000 µm), advanced platelet-rich fibrin (A-PRF), resorbable collagen membranes and screws tents (1.2 mm in diameter). Over the course of the study, a total of 63 GBR procedures were performed on these patients. Bone gains were measured by cone-beam computed tomography at 9.1 ± 2.0 months post-operative.

RESULTS

A significant mean increase (P < 0.001) of 3.2 ± 0.9 mm at the sites of the greatest bone defect was observed. This improvement was consistent across various locations, including both maxillary and mandibular regions, and in cases of terminal and embedded edentulism, without any post-operative complications during the entire post-operative follow-up. All patients benefited from implant placement following the bone augmentation protocol.

CONCLUSION

GBR combining particulate allografts, A-PRF, collagen membranes, and screw tents achieves reliable, predictable, and reproducible clinical gains that allow for future implant placement.

A preliminary investigation into the impact of soft tissue augmentation-based periodontal phenotype modification therapy for patients exhibiting class III decompensation

BACKGROUND

Patients with skeletal angle Class III malocclusion usually have inadequate hard and soft tissue volume at the mandibular anterior teeth. The labial proclination at the teeth may lead to gingival recession. The purpose of this study was to explore whether periodontal phenotype modification therapy with soft tissue augmentation (PhMT-s) can prevent gingival recession in these patients.

METHODS

Four patients with skeletal Class III malocclusion and a thin periodontal phenotype underwent surgical-orthodontic treatment. Prior to tooth movement, they underwent a minimally invasive vestibular incision with subperiosteal tunnel access combined with autogenous connective tissue grafts for periodontal phenotype modification with soft tissue augmentation (PhMT-s). The labial gingival thickness of the anterior mandibular teeth was measured at three distinct levels: at the cementoenamel junction (GT0), 3 mm apical to the CEJ (GT3), and 6 mm apical to the CEJ (GT6). These measurements were taken at baseline, three months following PhMT-s, and after tooth decompensation. Additionally, a biopsy sample was obtained from the PhMT-s site of one patient. All sections were subsequently stained using hematoxylin and eosin, Masson trichrome, Sirius Red, and immunohistochemistry.

RESULTS

The thickness of the labial gingiva was increased about 0.42 to 2.00 mm after PhMT-s. At the end of pre-orthognathic surgical orthodontic treatment, the thickness of the labial gingiva was increased about - 0.14 to 1.32 mm compared to the baseline and no gingival recession occurred after the pre-orthognathic surgical orthodontic treatment. The histologic results demonstrated that the grafts obtained from the PhMT-s site exhibited increased deposition of collagen fibers. Moreover, the proportion of type III collagen increased and the grafts displayed significantly reduced positive expression of CD31 and OCN.

CONCLUSIONS

PhMT-s increased the thickness of the soft tissue, stabilizing the gingival margin for teeth exhibiting a thin periodontal phenotype and undergoing labial movement. This is attributed to the increased deposition of collagen fibers.

Collagen-Based Medical Devices for Regenerative Medicine and Tissue Engineering

Assisted reproductive technologies are key to solving the problems of aging and organ defects. Collagen is compatible with living tissues and has many different chemical properties; it has great potential for use in reproductive medicine and the engineering of reproductive tissues. It is a natural substance that has been used a lot in science and medicine. Collagen is a substance that can be obtained from many different animals. It can be made naturally or created using scientific methods. Using pure collagen has some drawbacks regarding its physical and chemical characteristics. Because of this, when collagen is processed in various ways, it can better meet the specific needs as a material for repairing tissues. In simpler terms, collagen can be used to help regenerate bones, cartilage, and skin. It can also be used in cardiovascular repair and other areas. There are different ways to process collagen, such as cross-linking it, making it more structured, adding minerals to it, or using it as a carrier for other substances. All of these methods help advance the field of tissue engineering. This review summarizes and discusses the current progress of collagen-based materials for reproductive medicine.

Two-Step Periosteal Releasing Incision for Tension-Free Flap Closure After Implant Placement With Simultaneous Guided Bone Regeneration

We evaluated the effect of periosteal-releasing incisions on flap displacement in anterior maxillary sites following implant placement and simultaneously guided bone regeneration. Thirty patients, each requiring a single dental implant and guided bone regeneration in the maxillary esthetic zone, were recruited. After full-thickness flap elevation, the displacement of the flap was measured under a standardized tension of 1 Ncm. Then, a 2-step periosteal releasing incision was placed in the internal aspect of the flap, and the displacement was remeasured using the same standardized tension. Keratinized tissue width and mucosal thickness at the surgical site were recorded. Patient-reported outcomes were assessed at the 7- and 14-day recall visits. Flap displacement (primary outcome) was calculated before and after periosteal-releasing incisions. Multivariable linear regression models were used to evaluate the influence of mucosal thickness on flap displacement and adjusted for Keratinized tissue width. Primary wound closure was achieved in all patients. The mean difference in flap coronal displacement before and after the periosteal-releasing incisions was 8.2 mm (p < .0001). Adjusted regression models showed no association between mucosal thickness and keratinized tissue width with the amount of flap displacement (p = .770). Patient-reported outcome measures for pain, swelling, and bleeding amounted to 1.28 ± 1.93, 1.36 ± 1.87, and 0.0 ± 0.0 at 7 days and 0.11 ± 0.57, 0.56 ± 1.03, and 0.0 ± 0.0 at 14 days, respectively. Periosteal-releasing incisions using the 2-step procedure described here are a predictable technique to obtain coronal flap displacements >8 mm without increased surgical complications.

Effect of Membrane Fixation and the Graft Combinations on Horizontal Bone Regeneration: Radiographic and Histologic Outcomes in a Canine Model

The aim of this study was to determine the effect of membrane fixation and combinations of bone substitute materials and barrier membranes on horizontal bone regeneration in peri-implant defects. Eight mongrel dogs underwent chronic buccal peri-implant dehiscence defects creation and were randomized into 4 groups: (a) deproteinized bovine bone mineral 1 (DBBM1) with a native collagen membrane (CM) (BB group, positive control group), (b) DBBM1 with native CM and 2 fixation pins (BBP group), (c) DBBM2 with a cross-linked CM (XC group), and (d) DBBM2 with cross-linked CM and 2 fixation pins (XCP group). Following 16 weeks of healing, tissues were radiographically and histomorphometrically analyzed. The total augmented area was significantly larger in the BBP, XC, and XCP groups compared to the BB group (4.27 ± 3.21, 7.17 ± 7.23, and 6.91 ± 5.45 mm2 versus 1.35 ± 1.28 mm2, respectively; P = 0.022). No significant difference for the augmented tissue thickness was observed among the 4 groups. The augmented tissue thickness measured at 3 mm below the implant shoulder was higher in BBP, XC, and XCP than that in BB (2.43 ± 1.53, 2.62 ± 1.80, and 3.18 ± 1.96 mm versus 0.80 ± 0.90 mm, respectively), trending toward significance (P = 0.052). DBBM2 and a cross-linked CM were significantly more favorable for horizontal bone regeneration compared to DBBM1 and a native CM. However, when DBBM1 and a native CM were secured with fixation pins, outcomes were similar. The addition of pins did not lead to more favorable outcomes when a cross-linked CM was used.

Immediate versus early implant placement for single tooth replacement in the aesthetic area: A systematic review and meta-analysis

OBJECTIVES

To compare immediate implant placement (IIP) with early implant placement (EIP) for single tooth replacement in the aesthetic area in terms of aesthetic, clinical, and patient-reported outcomes.

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 February 2023. Randomized Controlled Trials (RCTs) comparing IIP with EIP were included for a qualitative and quantitative analysis. The primary outcome was vertical midfacial soft tissue change. Secondary outcomes were horizontal midfacial soft tissue change, vertical papillary change, pink esthetic score (PES), implant survival, buccal bone thickness, marginal bone level change, patient discomfort, chair time, and patient satisfaction.

RESULTS

Out of 1185 records, 6 RCTs were selected, reporting on 222 patients who received 222 single implants (IIP: 112 implants in 112 patients; EIP: 110 implants in 110 patients) in the anterior maxilla or mandible. Patients had a mean age ranging from 35.6 to 52.6 years and were followed between 8 and 24 months. Two RCTs showed some concerns, and four showed a high risk of bias. Four studies could be included in a meta-analysis on the primary outcome and three only considered cases with an intact buccal bone wall. Meta-analysis failed to demonstrate a significant difference in terms of vertical midfacial soft tissue change between IIP and EIP (mean difference: 0.31 mm, 95% CI [-0.23; 0.86], p = .260; I2 = 83%, p < .001). No significant differences were found for PES (standardized mean difference: 0.92, 95% CI [-0.23; 2.07], p = .120; I2 = 89%, p < .001), implant survival (RR: 0.98, 95% CI [0.93, 1.03], p = .480; I2 = 0%, p = .980), and marginal bone level change (mean difference: 0.03 mm, 95% CI [-0.12, 0.17], p = .700; I2 = 0%, p = .470). Insufficient data were available for meta-analyses of other secondary outcomes.

CONCLUSION

In low-risk patients with an intact buccal bone wall, there seems to be no difference between IIP and EIP in terms of aesthetic and clinical outcomes. The strength of this conclusion is rated as low since studies showed an unclear or high risk of bias. In addition, state-of-the-art therapy was only delivered in a minority of studies. Future RCTs should also provide data on patient-reported outcomes since these have been underreported.

Octacalcium phosphate collagen composite for periodontal regeneration in a canine one-wall intrabony defect

OBJECTIVE

This study aimed to evaluate the regenerative capacities of octacalcium phosphate collagen composite (OCP/Col) in one-wall intrabony defects in dogs. The background data discuss the present state of the field: No study has assessed the efficacy of OCP/Col for periodontal regeneration therapy despite the fact that OCP/Col has proved to be efficient for bone regeneration.

METHODS

In six beagle dogs, the mandibular left third premolars were extracted 12 weeks before the experimental surgery. Standardized bone defects (5 mm in height and 4 mm in width) were simulated on the distal surface of the second premolars and mesially on the fourth premolars. The defect was filled with either OCP/Col (experimental group) or left empty (control group). Histological and histomorphometric characteristics were compared 8 weeks after surgery.

RESULTS

No infectious or ankylotic complications were detected at any of the tested sites. The experimental group exhibited a significantly greater volume, height, and area of newly formed bone than the control group. The former also showed a greater height of the newly formed cementum than the latter, although the results were not statistically significant. The newly formed periodontal ligaments were inserted into newly formed bone and cementum in the experimental group.

CONCLUSION

OCP/Col demonstrated high efficacy for bone and periodontal tissue regeneration that can be successfully applied for one-wall intrabony defects.

Lateral bone augmentation with a composite graft covered with a stretched and pinned collagen membrane: A retrospective case series using cone-beam computed tomography

AIMS

(1) To assess the effectiveness of the Sausage Technique™ when applied for lateral bone augmentation by multiple experienced clinicians; (2) To identify risk indicators for a poor outcome and to assess the need for adjunctive surgery.

MATERIALS AND METHODS

All patients who had been treated with the Sausage Technique™ for lateral bone augmentation by three experienced surgeons between January 2019 and December 2021 were included in a retrospective case series. The Sausage Technique™ technique includes the use of autogenous bone chips and deproteinized bovine bone mineral (1:1 ratio), covered with a stretched and pinned collagen membrane. The increase in alveolar width between the pre-operative situation and 9 months was assessed at different levels on superimposed cone-beam CT scans.

RESULTS

Twenty-five augmentations performed in 25 patients (17 males, 8 females, mean age 51 years) were available for evaluation. Mean alveolar width increased from 4.35 to 7.43 mm at 3 mm below the crest. The mean increase of 3.08 mm (95% CI 2.10-4.06; p < 0.001) was significant. The outcome of non-containing single implant sites was significantly worse than the outcome of other sites (MD 2.67 mm; p = 0.008). The need for regrafting was 4% and the need for soft tissue augmentation was 48%. Twenty percent of the patients needed soft tissue augmentation due to a lack of keratinized mucosa width, and 32% due to a lack of buccal convexity. The former was mainly needed at multiple implant sites, whereas the latter was mainly required at single implant sites. All implant survived and remained healthy until the final follow-up.

CONCLUSION

The Sausage Technique™ is an effective bone augmentation technique. Non-containing single implant sites were associated with a poor outcome and adjunctive soft tissue augmentation was needed in about half of the patients.

Horizontal ridge augmentation in the maxillary aesthetic region using the autogenous circular cortical-lamina anchoring technique: A case series study

AIM

This case series aimed to evaluate the effectiveness of the autologous circular cortical lamina-anchoring (CCA) technique for horizontal bone augmentation in the maxillary aesthetic region.

MATERIALS AND METHODS

A total of 25 patients with 28 implants underwent horizontal bone augmentation using CCA followed by implant placement and crown delivery. The primary outcome measures were alveolar ridge width (ARW) and buccal bone thickness (BBT), whereas the secondary outcome measures included marginal bone loss (MBL), mid-facial mucosal margin loss (MML), clinical assessment of peri-implant and aesthetic parameters, patient-reported outcome measures (PROMs), and implant survival rates.

RESULTS

All 25 patients with 28 implants completed the treatment, no dropouts occurred. After CCA, the mean ARW at 1, 2, and 4 mm below the alveolar crest significantly increased from 2.38 ± 0.48, 2.85 ± 0.51, and 3.21 ± 0.53 mm to 6.80 ± 0.48, 6.99 ± 0.50, and 8.08 ± 0.52 mm, respectively. At the 3-year follow-up, the mean BBT0, BBT2, and BBT4 slightly decreased from 2.51 ± 0.26, 2.63 ± 0.31, and 2.75 ± 0.29 mm to 2.43 ± 0.27, 2.51 ± 0.30, and 2.64 ± 0.28 mm, respectively. Although the overall MBL was <0.15 mm, the results were statistically significant. The mean MML at the 3-year follow-up was 0.02 mm. All implant sites showed acceptable peri-implant and aesthetic outcomes. Incisions healed without complications, and no significant differences in PROMs observed at any time point. The 3-year follow-up showed a 100% implant survival rate.

CONCLUSION

The autologous CCA technique is a useful method for increasing ARW and maintaining BBT in the maxillary aesthetic region.

A Comparison of Guided Bone Regeneration vs. the Shell Technique Using Xenogeneic Bone Blocks in Horizontal Bone Defects: A Randomized Clinical Trial

In cases of severe horizontal atrophy, implant placement requires bone reconstruction procedures. The aim of this randomized controlled trial is to compare the outcomes of bone augmentation with simultaneous implant placement using the shell technique to the outcomes of guided bone regeneration (GBR) in cases of severely horizontal bone atrophy. This study was designed as a monocentric, parallel-group, randomized controlled trial with a six-month follow-up. Among the primary outcomes of this study, peri-implant bone regeneration and peri-implant bone defect closure were selected. Forty-four patients were recruited and equally divided between two groups. In the GRB group, a horizontal regeneration of 2.31 ± 0.23 mm was observed opposed to a horizontal regeneration of 2.36 ± 0.17 mm in the shell group (p = 0.87). A volumetric increase was observed in both groups, with an increase of 0.30 ± 0.12 cm3 in the GBR group and an increase of 0.39 ± 0.09 cm3 in the shell group, highlighting a significant difference between the two groups (p = 0.02). In conclusion, bone augmentation with simultaneous implant placement using the shell technique or guided bone regeneration in horizontal bone atrophy are both predictable therapeutic options.

Histological and radiological outcome after horizontal guided bone regeneration with bovine bone mineral alone or in combination with bone in edentulous atrophic maxilla: A randomized controlled trial

OBJECTIVE

To assess the radiological and histological outcome after horizontal guided bone regeneration (GBR) with deproteinized bovine bone mineral (DBBM) alone or in combination with particulate autogenous bone (PAB).

MATERIALS AND METHODS

Eighteen edentulous patients with an alveolar ridge of ≤4 mm were included in this split-mouth randomized controlled trial. Horizontal GBR with a graft composition of 100% DBBM (100:0) on one side and 90% DBBM and 10% PAB (90:10) on the other side were conducted in all patients. Cone beam computed tomography (CBCT) was obtained preoperatively, immediately postoperative, and after 10 months of healing. Width and volumetric changes in the alveolar process were measured on CBCT. Implants were placed after 10 months of graft healing where biopsies were obtained for histomorphometrical evaluation.

RESULTS

The gained widths were 4.9 (±2.4) mm (100:0) and 4.5 (±2.0) mm (90:10) at 3 mm from the top of the crest, and 5.6 (±1.3) mm (100:0) and 4.6 (±2.1) mm (90:10) at 6 mm from the top of the crest. The mean volumetric reductions were 32.8% (±23.8) (100:0) and 38.2% (±23.2) (90:10). Histomorphometry revealed that mean percentages of bone were 50.8% (±10.7) (100:0) and 46.4% (±11.3) (90:10), DBBM were 31.6% (±12.6) (100:0) and 35.4% (±14.8) (90:10), and non-mineralized tissue were 17.6% (±11.7; 100:0) and 18.2% (±18.2) (90:10). No significant differences were evident between in any evaluated parameters.

CONCLUSIONS

There were no additional effects of adding PAB to DBBM regarding bone formation, width changes, or volumetric changes after 10 months of graft healing.

Ridge preservation using a self-retaining block type bone substitute for extraction sockets with buccal dehiscence defects - A preclinical study

OBJECTIVE

To evaluate the effect of a self-retaining block-type bone substitute (srBB) on the dimensional stability of the horizontal ridge width at the coronal level in a buccal dehiscence model.

MATERIALS AND METHODS

Four box-shaped bone defects with a buccal dehiscence were surgically prepared in the partially edentulous mandible (n = 6). Experimental biomaterials were randomly assigned to each site: (1) Control group: no treatment, (2) particle-type bone substitute (PBS) group, (3) collagenated soft block bone substitute (csBB) group, and (4) self-retaining synthetic block bone (srBB) group. In all grafted groups, a collagen membrane covered the biomaterials. At 16 weeks, clinical, histological, and radiographic analyses were performed.

RESULTS

Three of the six blocks in the srBB group became exposed and fell out during the first week after surgery. Therefore, the remaining three specimens were renamed RsrBB group. The RsrBB group showed an increase horizontal ridge compared to the pristine bone width at 2-4 mm below the CEJ, while the other groups showed resorption (augmented width at 2 mm below: 4.2, 42.4, 36.2, and 110.1% in the control, PBS, csBB, and RsrBB groups, respectively). The mineralized bone area was largest in the RsrBB group (4.74, 3.44, 5.67, and 7.77 mm2 in the control, PBS, csBB, and RsrBB groups, respectively.).

CONCLUSIONS

The srBB group demonstrated the highest volume stability at the coronal level. These findings would potentially suggest that self-retaining block bone substitute might be a good candidate for alveolar ridge preservation.

Alveolar Bone Morphologic Predictors for Guided Bone Regeneration Outcome in Anterior Maxilla

OBJECTIVES

This study aimed to explore the influence of alveolar bone morphologic variables on the outcome of guided bone regeneration (GBR) in the anterior maxilla region.

METHODS

Twenty-eight patients who received single maxillary anterior tooth delayed implant placed simultaneously with GBR were recruited. Baseline data including age, gender, implant site, implant brand, and bone graft materials were recorded. The resorption rate of the grafted bone (RRGB), labial bone width at 0 mm, 2 mm, and 4 mm apical to the implant platform at Tn (LBW0Tn, LBW2Tn, LBW4Tn), implant angulation (IA), maximum bone graft thickness (MBGT), bone graft volume (BGV), and the initial bone morphologic variables bone concavity depth (BCD) and bone concavity angulation (BCA) were measured. The Pearson correlation analysis, analysis of variance (ANOVA), and optimal binning method were used to explore the potential predictors for GBR.

RESULTS

Among 28 patients, the labial bone width of implant and bone graft volume decreased significantly when measured 6 months after surgery. The mean percentage of RRGB was 49.78%. RRGB was not correlated with gender, age, bone graft material, IA, MBGT, bone graft volume at T1, implant site, and implant brand (P > .05). BCD and BCA were each moderately correlated with RRGB (r = -0.872 [P < .001] and r = 0.686 [P < .001], respectively). A BCD ≥1.03 mm and a BCA <155.30° resulted in a significantly lower percentage of RRGB (P < .001).

CONCLUSIONS

A significant grafted bone materials volume reduction was detected after GBR with collagen membrane and deproteinized bovine bone mineral (DBBM). The initial bone morphology can influence GBR outcome, and a bone concavity with a depth ≥1.03 mm and an angulation <155.30° led to a lower RRGB. BCD and BCA can be used as variables to predict the outcome of GBR.

Hard tissue stability outside the buccal bone arch contour after guided bone regeneration in the anterior maxilla: A retrospective cohort radiographic study

OBJECTIVES

To radiographically evaluate the stability of the bone substitute augmented outside the buccal bony arch contour in the maxillary esthetic zone.

MATERIALS AND METHODS

Patients who missed a single anterior tooth and received simultaneous GBR in implant surgery were included. The contralateral homonymous area of the implant site was horizontally mirrored as the individual bone arch contour. According to the relative position of the postoperative buccal grafts and bone arch contour at the implant shoulder, 62 patients were allocated into the outside-contour (OC) and inside-contour (IC) groups. Cone-beam computed tomography was performed before surgery, after implant insertion, before re-entry surgery, and at follow-up. The profilometric changes of the buccal bone plate were analyzed via the bone distance to the mirrored bony contour.

RESULTS

At the implant shoulder, the bone distance in the OC group was higher than that in the IC group, with statistically significant differences at re-entry surgery and follow-up. However, the bone grafts outside the bone arch contour were reduced into the contour after remodeling and showed more bone resorption than the IC group. At other vertical levels below the implant shoulder, bony grafting of overcontour 1-2 mm range was favorable to regenerate stable bone plates reaching the individual contour at follow-up.

CONCLUSIONS

The overaugmented bone outside the buccal bone arch contour tended to remodel into the original contour, which indicates that the anterior bone arch contour is worthy of careful observation for deciding buccolingual implant position and bone augmentation width.

A New Concept of Horizontal Bone Augmentation Using Collagen Bovine Bone Blocks Without Membrane at Implant Placement: A Preliminary Study

Purpose

A buccal bone thickness (BBT) of at least 1.8-2 mm is necessary to ensure long-term implant stability, and a bone grafting procedure is commonly needed to restore this BBT. This study aims to prove the effectiveness of a novel bone augmentation technique in which minero-organic bone substitutes are solely used to restore adequate BBT, excluding the need for coverage membranes.

Methods

Fifty partially edentulous patients having a residual bone width ranging between 5 and 6 mm were enrolled in this study. The horizontal buccal defects were grafted simultaneously at implant placement. Minero-organic collagen bovine bone blocks (CBBB) were placed on the outer side of the buccal bone wall, and adapted to the defect morphology through slow compressive movements. The grafted sites were not covered with any type of membrane nor stabilized with fixation pins. Cone-beam computed tomography scans were obtained pre-operatively, immediately post-surgery, and four months later. Scans were superimposed on the ITK-Snap software to measure the amount of bone gain and assess the percentage of CBBB resorption. Measurements were effectuated at four different levels apically to crestal level.

Results

Radiographic findings showed BBT increase and CBBB resorption in all cases, four months post-grafting. A mean horizontal bone gain of 1.39 mm was calculated at a crestal level.

Conclusion

Based on these findings, it appears that this novel and user-friendly bone grafting technique can achieve positive outcomes from both clinical and radiographic perspectives.

Vertical bone augmentation using collagenated or non-collagenated bone substitute materials with or without recombinant human bone morphogenetic protein-2 in a rabbit calvarial model

PURPOSE

The aim of this study was to determine 1) the bone-regenerative effect of porcine bone block materials with or without collagen matrix incorporation, 2) the effect of a collagen barrier, and 3) the effect of adding recombinant human bone morphogenetic protein-2 (rhBMP-2) to the experimental groups.

METHODS

Four treatment modalities were applied to rabbit calvaria: 1) deproteinized bovine bone mineral blocks (DBBM), 2) porcine bone blocks with collagen matrix incorporation (PBC), 3) porcine bone blocks alone without collagen matrix incorporation (PB), and 4) PBC blocks covered by a collagen membrane (PBC+M). The experiments were repeated with the addition of rhBMP-2. The animals were sacrificed after either 2 or 12 weeks of healing. Micro-computed tomography (micro-CT), histologic, and histomorphometric analyses were performed.

RESULTS

Micro-CT indicated adequate volume stability in all block materials. Histologically, the addition of rhBMP-2 increased the amount of newly formed bone (NB) in all the blocks. At 2 weeks, minimal differences were noted among the NB of groups with or without rhBMP-2. At 12 weeks, the PBC+M group with rhBMP-2 presented the greatest NB (P<0.05 vs. the DBBM group with rhBMP-2), and the PBC and PB groups had greater NB than the DBBM group (P>0.05 without rhBMP-2, P<0.05 with rhBMP-2).

CONCLUSIONS

The addition of rhBMP-2 enhanced NB formation in vertical augmentation using bone blocks, and a collagen barrier may augment the effect of rhBMP-2.

Horizontal and Vertical Defect Management with a Novel Degradable Pure Magnesium Guided Bone Regeneration (GBR) Membrane-A Clinical Case

Background and objectives: In guided bone regeneration (GBR), large defects comprising both horizontal and vertical components usually require additional mechanical support to stabilize the augmentation and preserve the bone volume. This additional support is usually attained by using non-resorbable materials. A recently developed magnesium membrane presents the possibility of providing mechanical support whilst being completely resorbable. The aim of this case report was to describe the application and outcome of the magnesium membrane in combination with a collagen pericardium membrane for GBR. Materials and methods: A 74 year old, in an otherwise good general health condition, was presented with stage 2 grade A periodontitis and an impacted canine. After extraction of the impacted canine, a defect was created with both vertical and horizontal components. The defect was augmented using the magnesium membrane to create a supportive arch to the underlying bone graft and a collagen pericardium membrane was placed on top to aid with the soft tissue closure. Results: Upon reentry at 8 months, complete resorption of the magnesium devices was confirmed as there were no visible remnants remaining. A successful augmentation outcome had been achieved as the magnesium membrane in combination with the collagen membrane had maintained the augmented bone well. Two dental implants could be successfully placed in the healed augmentation. Conclusions: In this case, the magnesium membrane in combination with a collagen pericardium membrane presented a potentially viable alternative treatment to titanium meshes or titanium-reinforced membranes for the augmentation of a defect with both horizontal and vertical components that is completely resorbable. It was demonstrated that it is possible to attain a good quality and quantity of bone using a resorbable system that has been completely resorbed by the time of reentry.

Tent-pole technique for alveolar ridge width preservation with a compromised buccal plate: a prospective cohort study

Objectives

The aim of this study was to assess the effectiveness of the tent-pole technique for alveolar ridge preservation of compromised alveolar socket following the surgical extraction of incurable single root premolars.

Materials and methods

This study was conducted on 12 patients who presented to the department of oral and maxillofacial surgery and had alveolar ridge preservation using tent-pole technique between August 2021 and February 2022. The alveolar ridge width was analyzed using cone beam computed tomography scans taken preoperative and 6 months postoperative. Statistical analysis was performed to assess the alveolar ridge width at different levels. The alveolar ridge width differences between periods were assessed with paired t-test. The comparison of alveolar ridge width loss according to jaw, sex, and different levels were done with unpaired t-test. The level of significance considered was 5% (α=0.05).

Results

The mean alveolar ridge width before surgery was 10.03 mm. After 6 months, the mean alveolar ridge width was 8.4 mm. The range of alveolar ridge width loss was between 0.6 and 3.22 mm with a mean of 1.63 (16.25%). There was no statistically significant difference in width loss between the maxilla and mandibular whether in males or females. Alveolar bone width loss was the greatest at W1 level (26.8%).

Conclusion

According to the results of this study, the authors conclude that the tent-pole technique could preserve the alveolar bone ridge width without bone graft materials.

Effect of polydeoxyribonucleotide on early bone formation in lateral bone augmentation with immediate implant placement: an experimental in vivo study

This study investigated early bone formation using collagenated biphasic calcium phosphate (CBCP) with or without polynucleotide (PDRN). Third (P3) or fourth (P4) premolars of six male beagle dogs were extracted and 5-mm-high dehiscence defects were created, followed by 3D-printed implant placement. The buccal bone defects were grafted with (i) CBCP and collagen membrane or (ii) CBCP soaked in polydeoxyribonucleotide (CBCP/PDRN) and collagen membrane. Samples of the experimental sites were harvested at 2- and 6-weeks post-surgery. The specimens were evaluated with radiologic and histomorphometric analysis. No significant differences were found between the CBCP and CBCP/PDRN groups in the micro-CT analysis at 2 or 6 weeks. No significant differences were observed in bone-to-implant contact (BIC) or bone area fraction occupancy (BAFO) in buccal augmented and lingual non-augmented areas. In the qualitative analysis, the new bone (NB) area and NB proportion in buccal augmented areas showed significantly higher values in the CBCP/PDRN group than in the CBCP group at 2 and 6 weeks. Peri-implant buccal dehiscence defects with immediate 3D-printed implant placement were corrected using a collagen membrane and CBCP or CBCP/PDRN. PDRN might have the potential to facilitate early bone formation with sufficient stability over time in dehiscence defects.

Efficacy of biomaterials for lateral bone augmentation performed with guided bone regeneration. A network meta-analysis

Bone regeneration is often required concomitant with implant placement to treat a bone fenestration, a dehiscence, and for contouring. This systematic review assessed the impact of different biomaterials employed for guided bone regeneration (GBR) simultaneous to implant placement on the stability of radiographic peri-implant bone levels at ≥12 months of follow-up (focused question 1), as well as on bone defect dimension (width/height) changes at re-assessment after ≥4 months (focused question 2). Only randomized controlled trials (RCTs) and controlled clinical trials (CCTs) that compared different biomaterials for GBR were considered. A Bayesian network meta-analysis (NMA) was performed using a random-effects model. A ranking probability between treatments was obtained, as well as an estimation of the surface under the cumulative ranking value (SUCRA). Overall, whenever the biological principle of GBR was followed, regeneration occurred in a predictable way, irrespective of the type of biomaterial used. A lower efficacy of GBR treatments was suggested for initially large defects, despite the trend did not reach statistical significance. Regardless of the biomaterial employed, a certain resorption of the augmented bone was observed overtime. While GBR was shown to be a safe and predictable treatment, several complications (including exposure, infection, and soft tissue dehiscence) were reported, which tend to be higher when using cross-linked collagen membranes.

Membrane barriers for guided bone regeneration: An overview of available biomaterials

Dental implants revolutionized the treatment options for restoring form, function, and esthetics when one or more teeth are missing. At sites of insufficient bone, guided bone regeneration (GBR) is performed either prior to or in conjunction with implant placement to achieve a three-dimensional prosthetic-driven implant position. To date, GBR is well documented, widely used, and constitutes a predictable and successful approach for lateral and vertical bone augmentation of atrophic ridges. Evidence suggests that the use of barrier membranes maintains the major biological principles of GBR. Since the material used to construct barrier membranes ultimately dictates its characteristics and its ability to maintain the biological principles of GBR, several materials have been used over time. This review, summarizes the evolution of barrier membranes, focusing on the characteristics, advantages, and disadvantages of available occlusive barrier membranes and presents results of updated meta-analyses focusing on the effects of these membranes on the overall outcome.

Dimensional changes after horizontal and vertical guided bone regeneration without membrane fixation using the retentive flap technique: A 1-year retrospective study

AIM

To evaluate the dimensional changes after horizontal and vertical guided bone regeneration (GBR) without membrane fixation using the retentive flap technique.

METHODS

This study retrospectively examined two cohorts that received vertical or horizontal ridge augmentations (VA or HA groups). GBR was performed using particulate bone substitutes and resorbable collagen membranes. The augmented sites were stabilized using the retentive flap technique without any additional membrane fixation. The augmented tissue dimensions were assessed using cone-beam computed tomography at preoperative, immediately postoperative (IP), 4 months (4M), and 1 year (1Y).

RESULTS

Postoperative vertical bone gain in 11 participants of VA group amounted to 5.96 ± 1.88 mm at IP, which decreased to 5.53 ± 1.62 at 4M and to 5.26 ± 1.52 mm at 1Y (intragroup p < 0.05). The horizontal bone gain at IP in 12 participants amounted to 3.98 ± 2.06 mm, which decreased to 3.02 ± 2.06 at 4M and to 2.48 ± 2.09 mm at 1Y (intragroup p < 0.05). The mean implant dehiscence defect height after 1Y was 0.19 ± 0.50 mm in the VA group, and 0.57 ± 0.93 mm in the HA group.

CONCLUSION

GBR without membrane fixation using the retentive flap technique seems to preserve the radiographic bone dimensions of vertically augmented sites. This technique may be less effective at preserving the width of the augmented tissue.

Bone regeneration in implant dentistry: Which are the factors affecting the clinical outcome?

The key factors that are needed for bone regeneration to take place include cells (osteoprogenitor and immune-inflammatory cells), a scaffold (blood clot) that facilitates the deposition of the bone matrix, signaling molecules, blood supply, and mechanical stability. However, even when these principles are met, the overall amount of regenerated bone, its stability over time and the incidence of complications may significantly vary. This manuscript provides a critical review on the main local and systemic factors that may have an impact on bone regeneration, trying to focus, whenever possible, on bone regeneration simultaneous to implant placement to treat bone dehiscence/fenestration defects or for bone contouring. In the future, it is likely that bone tissue engineering will change our approach to bone regeneration in implant dentistry by replacing the current biomaterials with osteoinductive scaffolds combined with cells and mechanical/soluble factors and by employing immunomodulatory materials that can both modulate the immune response and control other bone regeneration processes such as osteogenesis, osteoclastogenesis, or inflammation. However, there are currently important knowledge gaps on the biology of osseous formation and on the factors that can influence it that require further investigation. It is recommended that future studies should combine traditional clinical and radiographic assessments with non-invasive imaging and with patient-reported outcome measures. We also envisage that the integration of multi-omics approaches will help uncover the mechanisms responsible for the variability in regenerative outcomes observed in clinical practice.

Stability of guided bone regeneration with two ratios of biphasic calcium phosphate at implant sites in the esthetic zone: A randomized controlled clinical trial

AIMS

The aim of this randomized, double-blind, clinical trial was to compare the stability of the horizontal dimensions (facial bone thickness) of augmented bone using biphasic calcium phosphate (BCP) with hydroxyapatite/β-tricalcium phosphate ratio of either 60/40 or 70/30.

MATERIALS AND METHODS

Sixty dental implants placed with contour augmentation in the esthetic zone were randomized to 60/40 BCP (n = 30) or 70/30 BCP (n = 30). Cone-beam computed tomographic was used to assess facial bone thickness post-implantation and 6 months later at implant platform and 2, 4, and 6 mm apical to it.

RESULTS

The percentage of horizontal dimension reduction was 23.64%, 12.83%, 9.62%, and 8.21% in 70/30 BCP group, while 44.26%, 31.91%, 25.88%, and 21.49% in 60/40 BCP group at the level of the implant platform and 2, 4, and 6 mm apical, respectively. Statistically significant difference was found at 6 months at all levels of measurement (p-value < .05).

CONCLUSIONS

BCP bone grafts with HA/β-TCP ratio of 60/40 and 70/30 showed comparable outcomes for contour augmentation simultaneously with implant placement. Interestingly, the 70/30 ratio was significantly superior in maintaining facial thickness and showed more stable horizontal dimensions of the augmented site.

Band-Aid-Like Self-Fixed Barrier Membranes Enable Superior Bone Augmentation

In guided bone regeneration surgery, a barrier membrane is usually used to inhibit soft tissue from interfering with osteogenesis. However, current barrier membranes usually fail to resist the impact of external forces on bone-augmented region, thus causing severe displacement of membranes and their underlying bone graft materials, eventually leading to unsatisfied bone augmentation. Herein, a new class of local double-layered adhesive barrier membranes (ABMs) is developed to successfully immobilize bone graft materials. The air-dried adhesive hydrogel layers with suction-adhesion properties enable ABMs to firmly adhere to the wet bone surface through a "stick-and-use" band-aid-like strategy and effectively prevent the displacement of membranes and the leakage of bone grafts in uncontained bone defect treatment. Furthermore, the strategy is versatile for preparing diverse adhesive barrier membranes and immobilizing different bone graft materials for various surgical regions. By establishing such a continuous barrier for the bone graft material, this strategy may open a novel avenue for designing the next-generation barrier membranes.

Guided Bone Regeneration Using a Novel Magnesium Membrane: A Literature Review and a Report of Two Cases in Humans

Guided bone regeneration (GBR) is a common procedure used to rebuild dimensional changes in the alveolar ridge that occur after extraction. In GBR, membranes are used to separate the bone defect from the underlying soft tissue. To overcome the shortcomings of commonly used membranes in GBR, a new resorbable magnesium membrane has been developed. A literature search was performed via MEDLINE, Scopus, Web of Science and PubMed in February 2023 for research on magnesium barrier membranes. Of the 78 records reviewed, 16 studies met the inclusion criteria and were analyzed. In addition, this paper reports two cases where GBR was performed using a magnesium membrane and magnesium fixation system with immediate and delayed implant placement. No adverse reactions to the biomaterials were detected, and the membrane was completely resorbed after healing. The resorbable fixation screws used in both cases held the membranes in place during bone formation and were completely resorbed. Therefore, the pure magnesium membrane and magnesium fixation screws were found to be excellent biomaterials for GBR, which supports the findings of the literature review.

Complications and treatment errors in peri-implant hard tissue management

Bone augmentation procedures aim to regenerate the deficient alveolar ridge to properly place dental implants that are completely surrounded by bone. However, these are invasive and technically demanding surgeries that are not free of either complications or treatment errors. Careful patient selection and preparation is a mandatory process to reduce the rate of complications in bone regeneration procedures, irrespective of the technique used. It is important to assess the cost benefit of the intervention and to evaluate the potential impact on the patient's quality of life, especially in the elderly and medically compromised patients. Most common postoperative complications are wound dehiscences, which may be reduced, at least partially, by proper knowledge of the surgical technique and the craniofacial anatomy. Other complications that may appear are postoperative infections or nerve injuries. The aim of this narrative review is to summarize the best available scientific evidence on the incidence of complications, as well as the ideal strategies for their prevention and management. Depending on the severity of the complication, treatment approaches may vary and can include drug prescription or even surgical re-entries to remove exposed barrier membranes or contaminated bone grafts. Adequate prevention and proper management of complications associated with bone augmentation interventions are a requirement for clinicians carrying out these demanding procedures. A series of cases illustrating proper management of complications in different clinical scenarios is presented.

Individual "alveolar phenotype" limits dimensions of lateral bone augmentation

AIM

Alveolar ridge resorption following tooth extraction often renders a lateral bone augmentation inevitable. Some patients, however, suffer from severe early (during graft healing, E_res ) and/or late (during follow-up, L_res ) graft resorption. We explored the hypothesis that the "individual phenotypic dimensions" may partially explain the degree of such resorptions.

MATERIALS AND METHODS

Patients who underwent a guided bone regeneration (GBR) procedure were screened for inclusion according to the following criteria: (1) a relatively symmetrical maxillary arch; (2) an intact contra-lateral alveolar bone dimension; (3) the availability of a pre-operative cone-beam CT (CBCT); (4) a CBCT taken immediately after GBR, and (5) at least one CBCT scan ≥6 months after surgery. CBCT scans from different timepoints were registered and imported into the Mimics software (Materialise, Leuven, Belgium). Bone dimensions of the contra-lateral site of the augmentation, representing the "individual phenotypical dimension (IPD) of the alveolar crest", were superimposed on the augmented site and registered accordingly. As such, E_res and L_res could be measured over time, in relation to the IPD (in two dimensions; per millimetre apically from the alveolar crest, in the centre of the GBR), as well as in three dimensions (the entire GBR, 2 mm away from the mesial, distal, and apical border for standardization).

RESULTS

A total of 17 patients (23 augmented sites) were included. After E_res , the outline of the augmentation was in general located ±1 mm outside the IPD, but ≥1.5 years after GBR, it further moved towards the IPD (85% within 0.5 mm distance).

CONCLUSIONS

Within the limitations of this study, the results indicate that the dimensions of a lateral bone augmentation are defined by the "individual phenotypic bone boundaries" of the patient.

Application of Biodegradable Magnesium Membrane Shield Technique for Immediate Dentoalveolar Bone Regeneration

For the first time, the clinical application of the first CE registered magnesium membrane is reported. Due to the material characteristics of magnesium metal, new treatment methodologies become possible. This has led to the development of a new technique: the magnesium membrane shield technique, used to rebuild the buccal or palatal walls of compromised extraction sockets. Four clinical cases are reported, demonstrating the handling options of this new technique for providing a successful regenerative outcome. Using the technique, immediate implant placement is possible with a provisional implant in the aesthetic zone. It can also be used for rebuilding both the buccal and palatal walls simultaneously. For instances where additional mechanical support is required, the membrane can be bent into a double layer, which additionally provides a rounder edge for interfacing with the soft tissue. In all reported clinical cases, there was a good bone tissue regeneration and soft tissue healing. In some instances, the new bone had formed a thick cortical bone visible in cone beam computed tomography (CBCT) radiographs of the regenerated sites, which is known to be remodeled in the post treatment period. Overall, the magnesium membrane shield technique is presented as an alternative treatment option for compromised extraction sockets.

Comprehensive reparative effects of bacteriostatic poly(L-lactide-co-glycolide)/poly(L-lactide-co-ε-caprolactone) electrospinning membrane on alveolar bone defects in progressive periodontitis

Periodontitis is a chronic inflammatory disease that leads to the loss of alveolar bone, among several studies focusing on reconstructing periodontal bone caused by periodontitis, guided bone regeneration (GBR) is a promising approach. In this study a serial clinically applied antibiotics loaded poly(L-lactide-co-glycolide)/poly(L-lactide-co-ε-caprolactone) (PLGA/PLCA) fibrous mesh to prevent and reconstruct defective bone in periodontitis were prepared by electrospinning. Incorporation of antibiotics promoted the hydrophilicity but decreased the crystallinity of PLGA/PLCA membranes. Antibiotics could be sustained released from membranes. Metronidazole, minocycline, and doxycycline incorporated membranes could suppress Porphyromonas gingivalis (P. gingivalis) within 21 days in vitro. Metronidazole and minocycline incorporated membranes decreased 41% and 55.5% colony counts in rat gingival crevicular fluid in vivo. Minocycline-loaded membrane could support the proliferation of MC3T3-E1 cells and maintained 79% viability of human ligament fibroblasts cultured on it. And MC3T3-E1 cells could undergo osteoblastic differentiation when cultured with pure PLGA/PLCA membrane and minocycline incorporated membrane. Then in vivo repairable effects of those antibiotics loaded membranes were evaluated in alveolar bone defected P. gingivalis infected model. The application of minocycline loaded membranes, effectively prevented the bone resorption of periodontitis caused by P. gingivalis. After been treated with minocycline incorporated membrane, volume of defected bone of maintained at about 50% level of control rats. 8 weeks post-operation, newly regenerated bone was observed in the operative alveolar bone of the pure PLGA/PLCA membrane, metronidazole and minocycline incorporated PLGA/PLCA membrane treated groups. Minocycline/PLGA/PLCA electrospinning membrane is a promising GBR material that can be applied to guide regeneration of periodontitis-induced alveolar bone damage.

Immunohistochemical comparison of lateral bone augmentation using a synthetic TiO2 block or a xenogeneic graft in chronic alveolar defects

OBJECTIVES

To evaluate osteogenic markers and alveolar ridge profile changes in guided bone regeneration (GBR) of chronic noncontained bone defects using a nonresorbable TiO₂ block.

MATERIALS AND METHODS

Three buccal bone defects were created in each hemimandible of eight beagle dogs and allowed to heal for 8 weeks before GBR. Treatment was assigned by block randomization: TiO₂ block: TiO₂ -scaffold and a collagen membrane, DBBM particulates: Deproteinized bovine bone mineral (DBBM) and a collagen membrane, Empty control: Only collagen membrane. Bone regeneration was assessed on two different healing timepoints: early (4 weeks) and late healing (12 weeks) using several immunohistochemistry markers including alpha-smooth muscle actin (α-SMA), osteopontin, osteocalcin, tartrate-resistant acid phosphatase, and collagen type I. Histomorphometry was performed on Movat Pentachrome-stained and Von Kossa/Van Gieson-stained sections. Stereolithographic (STL) models were used to compare alveolar profile changes.

RESULTS

The percentage of α-SMA and osteopontin increased in TiO₂ group after 12 weeks of healing at the bone-scaffold interface, while collagen type I increased in the empty control group. In the defect area, α-SMA decreased in the empty control group, while collagen type I increased in the DBBM group. All groups maintained alveolar profile from 4 to 12 weeks, but TiO₂ group demonstrated the widest soft tissue contour profile.

CONCLUSIONS

The present findings suggested contact osteogenesis when GBR is performed with a TiO₂ block or DBBM particulates. The increase in osteopontin indicated a potential for bone formation beyond 12 weeks. The alveolar profile data indicated a sustained lateral increase in lateral bone augmentation using a TiO₂ block and a collagen membrane, as compared with DBBM and a collagen membrane or a collagen membrane alone.

Soft-tissue dimensional change following guided bone regeneration on peri-implant defects using soft-type block or particulate bone substitutes: 1-year outcomes of a randomized controlled clinical trial

AIM

To compare the peri-implant soft-tissue dimensional changes following guided bone regeneration between particulate (particle group) and collagenated soft-block-type (block group) biphasic calcium phosphate (BCP).

MATERIALS AND METHODS

This study investigated 35 subjects: 18 in the particle group and 17 in the block group. Cone-beam computed tomography obtained at 6 months post surgery and optical impressions taken periodically (before surgery, 6 months post surgery, and 1 year post surgery) were superimposed. The ridge contour changes over time and the peri-implant mucosal thicknesses were measured diagonally and horizontally, and analysed statistically.

RESULTS

The increases in diagonal (1.12 ± 0.78 mm) and horizontal (2.79 ± 1.90 mm) ridge contour of the block group were significantly higher than those in the particle group during the first 6 months (p < .05); however, the contour hardly changed thereafter (diagonal: 0.07 ± 0.75 mm; horizontal: -0.34 ± 1.26 mm), resulting in the 1-year contour changes similar between the two groups. Regardless of the type of BCP, the ridge contour increased significantly over 1 year when the dehiscence defect had a contained configuration (p < .05).

CONCLUSIONS

The increase in soft-tissue dimensions for 1 year was similar between the two groups. The mucosal contour increase was larger when the surgery was conducted in a more contained defect, and this was not influenced by the type of BCP.

The L-shape technique in guided bone regeneration with simultaneous implant placement in the esthetic zone: A step-by-step protocol and a 2-14 year retrospective study

OBJECTIVES

To describe the methodology of the "L-shape" technique in guided bone regeneration (GBR) with simultaneous implant placement and report on the clinical, esthetic, and patient satisfaction outcomes up to 14 years of follow-up.

MATERIAL AND METHODS

Fourteen patients treated with the "L-shape" technique were included in this retrospective study. The L-shape technique was performed by trimming and placing a soft-type bone block made of deproteinized bovine bone mineral with 10% collagen at the buccal-occlusal aspect of the dental implant. The remaining gaps were filled with deproteinized bovine bone mineral granules and the augmented area was covered with a collagen membrane. The following parameters were recorded:  probing depth (PD), bleeding on probing (BOP), plaque index (PI), keratinized tissue width (KT) and marginal bone level (MBL). Esthetic outcomes were assessed according to the pink esthetic score (PES) and the white esthetic score (WES). Patient satisfaction was evaluated by means of a numerical rating scale (0-10). The stability of each augmented site was assessed by measuring the volumetric changes between baseline (crown delivery) and the respective follow-up.

RESULTS

A total of 13 maxillary incisors and one maxillary canine in 14 patients were included. The mean follow-up period was 7.7 ± 3.8 years. PES values amounted to 10.7 ± 3.3 and WES to 8.8 ± 1.4. Patient satisfaction reached 9.4 ± 0.8. Mean PD at implant sites were 2.7 ± 0.7 mm while BOP amounted to 15.0 ± 0.2% and Pl to 5.0 ± 0.0%. Volumetric analyses revealed minimal changes at the augmented sites irrespective of the region of interest. Radiographic MBL remained relatively stable.

CONCLUSIONS

Within the limitation of the present study the L-shape augmentation procedure seems to be a reliable technique when performing GBR with simultaneous implant placement in the esthetic zone. Outcomes encompassed stable clinical and esthetic results accompanied by high levels of patient satisfaction. Future randomized controlled trials are warranted to confirm possible benefits of the L-shape technique over traditional approaches.

CLINICAL SIGNIFICANCE

The L-shape appears to be a simple yet promising technique in GBR with simultaneous implant placement that can easily be translated into clinical practice.

Degradable Pure Magnesium Used as a Barrier Film for Oral Bone Regeneration

The barrier membrane plays an extremely critical role in guided bone regeneration (GBR), which determines the success or failure of GBR technology. In order to obtain barrier membranes with high mechanical strength and degradability, some researchers have focused on degradable magnesium alloys. However, the degradation rate of pure Mg-based materials in body fluids is rather fast, thus posing an urgent problem to be solved in oral clinics. In this study, a novel micro-arc oxidation (MAO) surface-treated pure Mg membrane was prepared. Electrochemical tests, immersion experiments and in vivo experiments were carried out to investigate its potential use as a barrier membrane. The experimental results showed that the corrosion resistance of a pure Mg membrane treated by MAO is better than that of the uncoated pure Mg. The results of cell experiments showed no obvious cytotoxicity, which suggests the enhanced differentiation of osteoblasts. At the same time, the MAO-Mg membrane showed better biological activity than the pure Ti membrane in the early stage of implantation, exhibiting relatively good bone regeneration ability. Consequently, the MAO membrane has been proven to possess good application prospects for guided bone regeneration.

Polycaprolactone versus collagen membrane and 1‐year clinical outcomes: A randomized controlled trial

BACKGROUND

Polycaprolactone (PCL) is a synthetic aliphatic polyester widely used in biomedical applications with biodegradability in the body and promotes cell proliferation and differentiation. A newly developed bilayered PCL membrane was developed for possibly being used as a membrane in guided bone regeneration (GBR).

PURPOSE

To compare the clinical efficacy between a newly developed bilayered PCL membrane with a Cytoplast™ RTM collagen membrane for GBR with simultaneous implant placement.

MATERIALS AND METHODS

Twenty-four patients were randomized to PCL or RTM group, and a total of 24 dental implants were placed. Primary outcomes were patient mean buccal bone thickness (BBT) immediately postimplantation and at 6 months using cone-beam CT and soft tissue surface dimensional changes (STC) at crown insertion, 6 months, and 1 year after loading using intraoral scanner. Secondary outcomes included success rate, clinical parameters, healing index, implant stability, pink esthetic score, and marginal bone levels.

RESULTS

The percentage of reduced BBT at 6 months was 32.38%, 25.94%, and 23.96% in the test group and 34.42%, 14.75%, and 6.34% in the control group at the corresponding levels. The mean difference of changed BBT associated with PCL membrane, when compared to collagen membrane, at 6 months was -0.02 ± 0.18 mm (95% confidence interval [CI]: -0.40 to 0.35), 0.29 ± 0.28 mm (95% CI: -0.29 to 0.87), and 0.62 ± 0.38 mm (95% CI: -0.17 to 1.42) at 0, 2, and 4 mm from implant shoulder. Minimal loss of STC was observed in both groups up to 1 year of loading. The mean difference loss of surface dimensional change associated with PCL membrane, when compared to collagen membrane, at 1 year of loading was 0.31 ± 0.19 mm (95% CI: -0.07 to 0.70), 0.22 ± 0.26 mm (95% CI: -0.33 to 0.76), and 0.17 ± 0.30 mm (95% CI: -0.45 to 0.78) at 0, 2, and 4 mm from implant shoulder. None of these differences were statistically significant (unpaired t-test, degrees of freedom [df] = 22; p > 0.05).

CONCLUSION

Within the limits of this trial, both barrier membranes resulted in comparable outcomes for GBR with implant placement after 1 year in function. Further research is necessary with a larger sample size.

Primary flap closure in alveolar ridge preservation for periodontally damaged extraction socket: A randomized clinical trial

INTRODUCTION

The effect of primary wound closure (PC) on alveolar ridge preservation (ARP) in periodontally damaged sockets has yet to be fully discovered.

METHODS

Periodontally damaged sockets were allocated to one of the following groups: (1) ARP with PC (group PC), and (2) ARP without PC (group secondary wound closure [SC]). Following tooth extraction and flap elevation, granule-type xenogeneic bone substitute material and a collagen barrier were applied. Ridge change was evaluated using cone-beam computed tomographic (CBCT) scans immediately after ARP and at 4 months. Core biopsy specimens were examined histomorphometrically.

RESULTS

A total of 28 patients were included in the analysis (13 in group PC, 15 in group SC). Histomorphometrically, the percentage of newly formed bone was 26.2 ± 17.7% and 24.6 ± 18.4% in groups PC and SC, respectively (independent t-test, degree of freedom [df] = 25, p > 0.05). Horizontal ridge changes on CBCT were -4.9 ± 3.1 mm and - 4.2 ± 2.5 mm in groups PC and SC at the 1 mm level below the ridge crest, respectively (independent t-test, df = 26, p > 0.05). Approximately half of the sites required additional bone augmentation at implant placement.

CONCLUSIONS

ARP with/without PC yielded similar new bone formation and radiographic ridge change. This clinical trial was not registered prior to participant recruitment and randomization (https://cris.nih.go.kr/cris/search/detailSearch.do/19718).

Bone regeneration using titanium plate stabilization for the treatment of peri-implant bone defects: A retrospective radiologic pilot study

AIM

To 3-dimensional radiographically assess the effect of titanium plate in guided bone regeneration (GBR) for the treatment of peri-implant ridge defects in esthetic zone.

MATERIAL AND METHODS

Nineteen patients with buccal peri-implant defects in the maxillary esthetic zone were treated with GBR using xenograft, autogenous bone, and collagen membrane. Subjects were divided into two groups: control (conventional GBR, 10 patients with 16 implants) and test (GBR with an adjunctive titanium plate; nine patients with 15 implants). Cone-beam computed tomography (CBCT) images obtained immediately after and 5-7 months following GBR were used to assess buccal crestal bone level (BBL) and buccal bone thickness (BBT) at different implant levels.

RESULTS

Thirty-one implants in 19 patients were evaluated. Titanium plate exposure occurred in three cases (33.33%) of the test group. After 5-7 months, the mean BBL was located 1.48 ± 0.71 mm coronal to the platform in the test group and 0.90 ± 3.03 mm coronal to the platform in the control group (p = 0.03). The mean over all BBT (BBT-M) was 4.16 ± 0.48 mm in the test group and 2.38 ± 0.97 mm in the control group (p < 0.01). More resorption occurred in the control group than in the test group regarding mean BBL (3.00 ± 3.11 mm vs. 0.78 ± 0.79 mm, respectively; p = 0.04), BBT-M change (1.87 ± 1.59 mm vs. 0.56 ± 0.33 mm, respectively; p = 0.02), and percentage change in BBT-M (40.69 ± 24.01% vs. 11.53 ± 5.86%, respectively; p < 0.01).

CONCLUSION

In the short-term, titanium plate-enhanced GBR maintained ridge dimensions better than conventional GBR did.

A Randomized Controlled Trial of Guided Bone Regeneration for Peri-Implant Dehiscence Defects with Two Anorganic Bovine Bone Materials Covered by Titanium Meshes

The aim of this study is to compare two low-temperature sintered anorganic bovine bone materials (ABBMs), Bio-Oss (Geistlich, Wolhusen, Switzerland) and A-Oss (Osstem, Seoul, Korea), for GBR in dehiscence defects. A single implant was placed simultaneously with GBR in the buccal or bucco-proximal osseous defect by double-layering of inner allograft and outer ABBM, covered by a preformed ultrafine titanium mesh and an absorbable collagen membrane. Grafted volume changes were evaluated by cone-beam computed tomography, taken preoperatively (T0), immediately after implant surgery (T1), after re-entry surgery (T2), and after delivery of the final restoration (T3). The density of the regenerated bone was assessed by measuring the probing depth on the buccal mid-center of the mesh after removing the mesh at T2. Postoperative sequelae were also recorded. Grafted volume shrinkage of 46.0% (0.78 ± 0.37 cc) and 40.8% (0.79 ± 0.33 cc) in the Bio-Oss group (8 patients) and A-Oss group (8 patients), respectively, was observed at T3 (p < 0.001). There were no significant differences in grafted volume changes according to time periods or bone density between the two groups. Despite postoperative mesh exposure (3 patients), premature removal of these exposed meshes and additional grafting was not necessary, and all implants were functional over the 1-year follow-up period. Both ABBMs with titanium meshes showed no significant difference in the quantity and density of the regenerated bone after GBR for peri-implant defects.

Biodegradable magnesium barrier membrane used for guided bone regeneration in dental surgery

Barrier membranes are commonly used as part of the dental surgical technique guided bone regeneration (GBR) and are often made of resorbable collagen or non-resorbable materials such as PTFE. While collagen membranes do not provide sufficient mechanical protection of the covered bone defect, titanium reinforced membranes and non-resorbable membranes need to be removed in a second surgery. Thus, biodegradable GBR membranes made of pure magnesium might be an alternative. In this study a biodegradable pure magnesium (99.95%) membrane has been proven to have all of the necessary requirements for an optimal regenerative outcome from both a mechanical and biological perspective. After implantation, the magnesium membrane separates the regenerating bone from the overlying, faster proliferating soft tissue. During the initial healing period, the membrane maintained a barrier function and space provision, whilst retaining the positioning of the bone graft material within the defect space. As the magnesium metal corroded, it formed a salty corrosion layer and local gas cavities, both of which extended the functional lifespan of the membrane barrier capabilities. During the resorption of the magnesium metal and magnesium salts, it was observed that the membrane became surrounded and then replaced by new bone. After the membrane had completely resorbed, only healthy tissue remained. The in vivo performance study demonstrated that the magnesium membrane has a comparable healing response and tissue regeneration to that of a resorbable collagen membrane. Overall, the magnesium membrane demonstrated all of the ideal qualities for a barrier membrane used in GBR treatment.

•

First report on a biodegradable metallic barrier membrane for use in oral surgery is presented.

•

The mechanical stability of the metallic barrier membrane provides a careful shielding of the augmented bone defect.

•

Full resorption of metallic barrier membrane and bone healing is completed long before current standards for second surgical patient treatment.

Immediate implant placement utilizing vestibular socket therapy versus early implant placement with contour augmentation for rehabilitation of compromised extraction sockets in the esthetic zone: A randomized controlled clinical trial

OBJECTIVE

The present randomized controlled trial compares for the first time the vestibular socket therapy (VST) to the contour augmentation technique in the management of compromised fresh extraction sockets in the maxillary esthetic zone, regarding mid-facial soft tissue changes (primary outcome), mesial and distal papillae dimensions, horizontal soft tissue changes and labial bone plate thickness at apical, middle and coronal levels (secondary outcomes) over 1-year.

MATERIALS AND METHODS

Forty participants with single nonrestorable maxillary teeth in the esthetic zone were randomized into two groups; VST (test; n = 20) utilizing vestibular access for guided bone regeneration (GBR) with immediate implant placement, or contour augmentation (control; n = 20) undergoing an initial healing period followed by implant placement with GBR through a conventional access flap.

RESULTS

All implants were successfully osseo-integrated, except for one implant in the test group. VST showed significantly less mid-facial soft tissue changes of -0.53 ± 1.17 mm versus -1.87 ± 0.69 mm in the control group (p < 0.001). Similarly, changes in mesial papilla (test = -0.64 ± 0.95 mm, control = -1.20 ± 0.81 mm), distal papilla (test = -0.56 ± 1.17 mm, control = -1.26 ± 0.63 mm), horizontal soft-tissue (test = -0.82 ± 0.95 mm, control = -1.84 ± 0.88 mm; p < 0.05) were significantly less in VST. Intra-group comparisons demonstrated a significant increase in labial bone thickness, with no differences between groups. Regression analysis revealed a significant correlation between VST as well as increased coronal bone thickness with the reduction in mid-facial soft-tissue changes.

CONCLUSION

The VST showed less soft-tissue changes and could represent an innovative technique for implant placement in the maxillary esthetic zone. Both techniques showed a high implant survival rate and increased bone thickness after 12 months.

Effect of collagen membrane fixation on ridge volume stability and new bone formation following guided bone regeneration

AIM

To test the effect of membrane fixation on ridge volume stability and new bone formation using guided bone regeneration.

MATERIALS AND METHODS

In eight beagle dogs, after bilateral extraction of the maxillary pre-molars, a box-shaped defect was created on each side. All defect sites were augmented with a particulate bone substitute material, covered with either one of two non-cross-linked collagen membranes (CM1 or CM2) with or without fixation (-F or -UF). Samples were collected after 8 weeks. Histomorphometric and micro-computed tomography analyses were performed.

RESULTS

Membrane fixation made no significant difference to the total augmented volume for both membranes (p > .05). Histological data indicated that at the ridge crest the augmented tissue width amounted to 2.4 ± 0.4 mm in the group CM1-F and 2.4 ± 0.5 mm in the group CM1-UF, with no significant difference between the groups. Conversely, in CM2-F the augmented tissue width was significantly larger than in CM2-UF (2.3 ± 0.1 vs. 1.57 ± 0.27, p < .05).

CONCLUSIONS

Membrane fixation in contained defects failed to improve ridge volume stability regardless of the membrane type. However, it may enhance the width of the augmented ridge at the coronal portion depending on the type of membrane.

Modified membrane fixation technique in a severe continuous horizontal bone defect: A case report

BACKGROUND

Continuous severe horizontal bone defect is common in the aesthetic maxillary anterior area, and presents a major challenge in implant dentistry and requires predictable bone augmentation to increase the width of the alveolar bone.

CASE SUMMARY

A 24-year-old man, with a history of well-controlled IgA nephropathy, presented to the Dentistry Department of our hospital complaining of missing his right maxillary anterior teeth 1 mo ago. Severe horizontal alveolar bone defects at sites of teeth 12, 13 and 14 were diagnosed. A modified guided bone regeneration surgical approach stabilizing the absorbable collagen membrane and particulate graft materials by periosteal diagonal mattress suture (PDMS) combined with four corner pins was used for this severe continuous horizontal bone defect. The outcome revealed that the newly formed alveolar ridge dimension increased from 0.72 mm to 11.55 mm horizontally 10 mo postoperatively, with no adverse events. The implant surgery was successfully performed.

CONCLUSION

This case highlights that PDMS combined with four corner pins is feasible to maintain the space and stabilize the graft and membranes in severe continuous horizontal bone defect.

Stability of contour augmentation of implant-supported single crowns in the esthetic zone: One-year cone-beam computed tomography results of a comparative, randomized, prospective, two-center clinical study using two different bone grafting techniques in early implant placement

BACKGROUND

Early implant placement with contour augmentation could provide support and volume to the hard and soft tissues. Herein, we aimed to ascertain whether freeze-dried bone allograft (FDBA) shares with deproteinized bovine bone material (DBBM) the results for esthetic outcomes for anterior teeth and stability of peri-implant facial bone thickness and height by conducting guided bone regeneration.

METHODS

Forty-eight patients were randomly assigned into two groups. In the control group, autogenous bone chips was used to cover the exposed implant surface, followed by a layer of DBBM. This graft combination was then covered with two layers of collagen membrane. In the test group, the exposed implant surface was covered with FDBA, combined with the collagen membrane. During this study, the hard tissue dimensional changes were measured at 12-months post-implant loading by using cone-beam computed tomography.

RESULTS

At 12 months postoperatively, all 48 implants were clinically successful. The mean thickness of facial bone walls ranged from 1.6 to 2.45 mm at the three levels of measurement in the control group and ranged from 1.6 to 2.10 mm in the test group. The mean facial vertical bone wall peak (IP-FC) after loading 1 year presented with values of 0.8 mm (range, 0.0 to 1.25 mm) and 0.5 mm (range, 0.1 to 1.1 mm) coronal to the implant platform in control and test implants, respectively. There were no significant differences in facial bone wall thickness and IP-FC between groups.

CONCLUSIONS

This study demonstrated that autogenous bone chips plus DBBM or FDBA showed similar outcome of peri-implant buccal bone stability in early implant placement after 1 year.

Randomized controlled clinical trial comparing guided bone regeneration of peri-implant defects with soft-type block versus particulate bone substitutes: Six-month results of hard-tissue changes

AIM

To test whether soft-type block bone substitute used for guided bone regeneration (GBR) of peri-implant defects leads to a different dimension of the augmented hard tissue than particulate bone substitute.

MATERIALS AND METHODS

In 40 patients, 40 two-piece dental implants were placed >2 months after tooth extraction. Following random allocation, 20 peri-implant bone dehiscences were grafted with a soft-type block made of synthetic biphasic calcium phosphate (BCP) + collagen and 20 bone dehiscences with particulate BCP. All the sites were covered with a collagen membrane stabilized with titanium pins. Immediately after wound closure and after 6 months, the horizontal dimension (HD) of the augmented hard tissue was measured at the level of implant shoulder using cone beam computed tomography. During re-entry at 6 months, the defect fill was clinically assessed.

RESULTS

At 6 months, the median HD measured 1.15 mm (mean: 1.31 mm) in the soft-block group and 0.93 mm (mean: 1.05 mm) in the particulate group (p = .6). At 6 months, 7.1% of contained defects and 61.9% of non-contained defects showed an incomplete vertical defect fill.

CONCLUSIONS

Soft-type block of BCP + collagen used for GBR of peri-implant defects did not differ from particulate BCP regarding the dimension of the augmented hard tissue after 6 months of healing.

Analysis of a Pure Magnesium Membrane Degradation Process and Its Functionality When Used in a Guided Bone Regeneration Model in Beagle Dogs

For the surgical technique of guided bone regeneration (GBR), the choice of available barrier membranes has until recently not included an option that is mechanically strong, durable, synthetic and resorbable. The most commonly used resorbable membranes are made from collagen, which are restricted in their mechanical strength. The purpose of this study is to evaluate the degradation and regeneration potential of a magnesium membrane compared to a collagen membrane. In eighteen beagle dogs, experimental bone defects were filled with bovine xenograft and covered with either a magnesium membrane or collagen membrane. The health status of the animals was regularly monitored and recorded. Following sacrifice, the hemimandibles were prepared for micro-CT (μ-CT) analysis. Complications during healing were observed in both groups, but ultimately, the regenerative outcome was similar between groups. The μ-CT parameters showed comparable results in both groups in terms of new bone formation at all four time points. In addition, the μ-CT analysis showed that the greatest degradation of the magnesium membranes occurred between 1 and 8 weeks and continued until week 16. The proportion of new bone within the defect site was similar for both treatment groups, indicating the potential for the magnesium membrane to be used as a viable alternative to collagen membranes. Overall, the new magnesium membrane is a functional and safe membrane for the treatment of defects according to the principles of GBR.

Bioactive Glasses in Periodontal Regeneration: Existing Strategies and Future Prospects-A Literature Review

The present review deals with bioactive glasses (BGs), a class of biomaterials renowned for their osteoinductive and osteoconductive capabilities, and thus widely used in tissue engineering, i.e., for the repair and replacement of damaged or missing bone. In particular, the paper deals with applications in periodontal regeneration, with a special focus on in vitro, in vivo and clinical studies. The study reviewed eligible publications, identified on the basis of inclusion/exclusion criteria, over a ranged time of fifteen years (from 1 January 2006 to 31 March 2021). While there are many papers dealing with in vitro tests, only a few have reported in vivo (in animal) research, or even clinical trials. Regardless, BGs seem to be an adequate choice as grafts in periodontal regeneration.

Surgical guides for guided bone augmentation: an in vitro study

AIM

To validate in vitro the accuracy of a novel method for bone augmentation of horizontal alveolar bone defects with the help of a surgical guide.

MATERIAL AND METHODS

Six cone-beam computed tomography scans of patients requiring horizontal bone augmentation were segmented and 3D printed. Two surgeons performed the bone augmentation surgery twice for each case on 3D printed models, using either a conventional or guided protocol. Each surgeon virtually planned the desired graft shape beforehand. The resulting grafts were compared linearly and volumetrically to the plan; graft density and surgical time were also analyzed.

RESULTS

There was significantly less graft volume outside the planned volume with the guided protocol (36.8% ± 14.1 vs 19.6% ± 12.3, p < 0.01). The use of a guide increased graft accuracy at several measurement points, resulting in less overfill when using the guided protocol (1.7 ± 1.7 mm at the most coronal point, 0.2 mm ± 1.4 at 25%, 0.0 mm ± 0.9 at 50%, 0.1 mm ± 1.1 at 75%, 0.4 mm ± 1.4 apically). Graft thickness was increased 1 mm coronally from the planned graft (2.8 mm ± 2.3 vs 1.8 mm ± 2.2, p = 0.04). Surgical time increased significantly when using a guide (a difference of 2m26s).

CONCLUSION

The technique, tested here in vitro, allows surgeons to improve the accuracy of the resulting graft shape, to better compact material in the coronal portion of the graft, and to reduce the amount of graft material placed outside the planned volume.