Corticocancellous Porcine Bone Research Articles

Cone-Beam Computed Tomography and Histological Findings for Socket Preservation Techniques Using Different Grafting Materials: A Systematic Review

Socket preservation techniques have been used to maintain the ridge dimension following tooth extraction. The materials used influence the quality and quantity of newly formed bone. Therefore, the aim of this article was to systematically review the literature reporting both histological and radiographic outcomes of socket preservation techniques after tooth extraction in human subjects. A systematic electronic search was performed in the electronic databases. English language clinical studies that were published between 2017 and 2022 and included both histological and radiographic findings for the test and control groups. Our primary search produced 848 articles, and of these, 215 were duplicate studies. A total of 72 articles were then eligible for full-text reading. The review included eight studies that met its inclusion criteria. Three outcomes were compared in the included studies. The percentage of newly formed bone ranged from 21.34 ± 9.14% to more than 50% of new bone formation. The materials that showed more than 50% of newly formed bone formation were demineralized dentin graft, platelet-rich fibrin, freeze-dried bone allograft, corticocancellous porcine, and autogenous bone. Four Studies did not report the percentage of the residual graft materials, while those who reported showed a variable range of a minimum 1.5% to more than 25%. One study did not report the changes in horizontal width at the follow-up period, while other studies ranged from 0.6 mm to 10 mm. Socket preservation represents an efficient technique to preserve the ridge contour with satisfactory newly formed bone in the augmented site and maintaining the vertical and horizontal dimensions of the ridge.

Changes in Alveolar Bone Width Following Immediate Implant and Fresh Socket Preservation with Xenogeneic Gap-Filling Material Versus Guided Tissue Healing with Anatomical Tooth-Shaped Caps: A 3-Year Retrospective Case-Control Study.

This study aimed to calculate the 3-year dimensional change in crestal bone width when dental implants placed in postextraction sockets underwent two alternative techniques for alveolar preservation. Fresh sockets that had undergone immediate implant placement were categorized into one of two groups depending on the procedure type. For the xenogeneic biomaterial grafted (BG) group, the gaps between the metallic implant surfaces and the bony walls were filled with corticocancellous porcine bone; in the anatomical cap group, in which patients were treated with guided tissue healing (GTH), cross-linkable acrylic resin caps were immediately screwed on the implants. Absolute measurements of the alveolar width were performed on 3D images acquired before tooth extraction (thereby ensuring correct surgical treatment) and 3 years after surgery. Nonparametric statistics were performed, with the level of significance set at 1%. The results of 46 implants (placed in 36 patients) were analyzed, and 100% survival rates were reported for both groups at 3 years postsurgery. Minor swelling of treated areas was observed the first few days of healing, but neither mucositides, dehiscence events, nor suppurations occurred. At 3 years postsurgery, loss in alveolar ridge width was higher for the BG group (-1.1 ± 0.6 mm) than for the GTH group (0.0 ± 0.3 mm); moreover, these changes were significantly different (P < .0001). This clinical and radiographic data analysis suggests that the implant sites that received a xenogeneic filling material were less effective in maintaining the preoperative alveolar bone width than sites that underwent GTH with immediate implants and anatomical tooth-shaped caps.

Healing Patterns of Non-Collagenated Bovine and Collagenated Porcine Xenografts Used for Sinus Floor Elevation: A Histological Study in Rabbits.

Objective: To compare healing of collagenated and non-collagenated xenografts used for maxillary sinus floor elevation. Materials and Methods: Two different xenografts were used: deproteinized bovine bone (DBBM group) and collagenated corticocancellous porcine bone (collagenated group). Healing was studied after 2, 4, and 8 weeks. The loss of dimensions of the elevated area and the percentages of new bone, xenograft remnants, osteoclastic zones, vessels, inflammatory infiltrates, and soft tissues were analyzed. Three regions were evaluated: close to the bone walls (bone wall region), subjacent the sinus mucosa (submucosa region), and the center of the elevated area (middle region). The primary variables were the percentage of new bone and xenograft remnants. Results: Between 2 and 8 weeks, the elevated areas showed a reduction of 16.3% and 52.2% in the DBBM and collagenated groups, respectively (p < 0.01 between the two areas after 8 weeks). After 8 weeks, the highest content of new bone was observed in the bone wall region, which was higher in the collagenated group than in the DBBM group (41.6% and 28.6%, respectively; p < 0.01). A similar quantity of new bone was found between the two groups in other regions. A higher percentage of vessels in all regions evaluated (p < 0.01) and soft tissue in the sub-mucosa region (p < 0.05) was found in the collagenated group than in the DBBM group. Conclusions: The present study showed that both xenografts allowed new bone formation. In comparison with the non-collagenated xenograft, the collagenated xenograft underwent higher resorption, resulting in greater shrinkage of the elevated space after sinus lifting and a higher content of new bone in the regions close to the bone walls. Clinical relevance: In this study, the region adjacent to the bone wall showed the highest new bone content. This region resembles the base of the sinus, closest to the sinus floor and walls, and is the most important region from a clinical point of view because it is where the implant will be installed. Residues of the biomaterial remained after 8 weeks of healing. Other reports have shown that these biomaterial residues may interfere with the integration of implants.

Influence on Implant Bone Healing of a Collagen Membrane Placed Subjacent the Sinus Mucosa-A Randomized Clinical Trial on Sinus Floor Elevation.

Background: Perforation of the sinus mucosa is quite a frequent complication that might occur during sinus floor elevation. The perforation is often protected with a collagen membrane to avoid the extrusion of graft particles within the sinus. However, this procedure might hinder the innate osteogenic potential of the sinus mucosa. Hence, the aim of the study was to evaluate the influence of a placement of a collagen membrane subjacent the Schneiderian membrane during sinus floor elevation on implant bone healing. Methods: Twenty volunteers took part in the trial. Ten were randomly included in the group that received a collagen membrane subjacent the sinus mucosa (Mb group), and ten did not receive the membrane (non-Mb group). A collagenated corticocancellous porcine bone was used to fill the elevated space. Six 6 months after the sinus floor elevation, a mini implant was placed transcrestally and retrieved after a further 3 months. Histological analyses were then performed on the full body of the mini implant as well as on its coronal and apical portions. Results: The new bone apposition proportion onto the implant surface was similar in the Mb and non-Mb groups, both in the apical and coronal portions of the mini implants. A lesser amount of graft was found in contact with the surface. New bone density around the mini implants were similar both in the apical and coronal portions. However, a statistically higher proportion of graft particles was found in the Mb group compared to the non-membrane group. Conclusions: The placement of a collagen membrane subjacent the sinus mucosa did not affect bone healing at implants and bone density.

Influence of the use of autogenous bone particles to close the access window after maxillary sinus floor augmentation: a micro‐computed tomography and positron emission tomography study in rabbits

AimThe purpose of this study was to evaluate using microCT and positron emission tomography (PET) analysis, the influence on bone healing of the placement of particulate autogenous bone in the antrostomy, and in the subjacent region after maxillary sinus elevation with xenograft.Material and methodsThe sinus mucosa was elevated in sixteen male New Zealand rabbits and they were both grafted with a collagenated cortico-cancellous porcine bone. The antrostomy and the near subjacent region were filled with either the same xenograft (control site) or with particulate autogenous bone (test site) harvested from the tibia. The antrostomies were covered with collagen membranes. MicroCT (measured in Hounsfield Units) and microPET (kBq/cm3) using sodium fluoride infiltration (18F-NaF) were performed at the time of euthanasia that was performed after 1 and 8 weeks of healing, using 8 animals in each group. The Wilcoxon test was used for analysis.ResultsAt the microCT analysis, after 1 and 8 weeks of healing, no statistically significant differences were found between groups. Bone increased and xenograft decreased significantly between the two periods of healing. At the microPET analysis, the percentage of bone increased significantly over time in both test and control groups and no significant differences were found between groups.ConclusionThe placement of autogenous bone in the antrostomy and the subjacent region after maxillary sinus elevation did not enhance bone formation compared with sites where only xenograft was used. Both microCT and microPET showed increase bone formation over time.

Influence of the Use of a Collagen Membrane Placed on the Bone Window after Sinus Floor Augmentation-An Experimental Study in Rabbits.

Background: We studied the influence on healing of a resorbable membrane covering the osteotomy site after maxillary sinus grafting, evaluated in different regions of the augmented area. Methods: Maxillary sinus augmentation was performed in 24 New Zealand rabbits. Osteotomy, 4 × 6 mm, were performed bilaterally. A collagenated cortico-cancellous porcine bone was used to fill the elevated region. A collagen membrane was randomly placed over the osteotomy site on one side (MG), and the other side was left uncovered (NMG). The animals were euthanized after 2, 4, and 8 weeks; and histomorphometric analysis was performed in eight different regions. Results: New bone percentages were similar in both groups. There were no statistically significant differences. In MG, the overall percentages were 15.6 ± 7.3%, 22.9 ± 6.1%, and 24.9 ± 12.0% after 2, 4, and 8 weeks, respectively. In NMG, the percentages were 11.2 ± 4.5%, 24.1 ± 5.7%, and 24.5 ± 15.7%, respectively. The proportions of new bone in the various regions after 8 weeks were 31 ± 8.9% and 29.9 ± 9.1% in the bone walls region, 25 ± 10.1% and 32.8 ± 9.1% in the submucosa region, 22.6 ± 21.6% and 10.9 ± 11.5 in the middle region, 17.3 ± 14% and 13.4 ± 9.8% in the close-to-window region, and 21.8 ± 11.6%, 19.1 ± 6.4% in the osteotomy region—for MG and NMG, respectively. Conclusions: In both groups the greatest amounts of bone formation occurred near to the pre-existing bone walls, followed by the sub-mucosa region. The smallest amounts were found in the close-to-window region, followed by the central region. The placement of a collagen membrane to cover the osteotomy site did not influence the amount of new bone formation after sinus grafting.

Bone remodeling around implants placed after socket preservation: a 10-year retrospective radiological study

BackgroundTo evaluate and compare the long-term clinical and radiological outcomes of post-extraction sockets after ridge preservation either with porcine xenograft or collagen alone. Patients underwent single-tooth extraction in the posterior mandible. Fresh extraction sockets were filled with pre-hydrated cortico-cancellous porcine bone or collagen sponge. Two or 3 months later, a ridge expansion technique with immediate implant positioning placement was performed. Primary (alveolar width changes) and secondary outcomes (adverse events and long-term maintenance of buccal plate covering the implant) were evaluated.ResultsThirty-four women and 20 men were selected: 30 implants (group A) placed into healed post-extraction sockets grafted with porcine bone and 24 (group B) into sockets filled with a collagen sponge. There was a significant loss in width in both groups from the first and second surgery (ranging between 2.7 mm and 4.5 mm). The ridge splitting with bone expansion resulted in significant long-term increases in width for both procedures and implant sites. Non-significant differences in alveolar width were registered between the groups at 10-year follow-up even if the analysis of the implant buccal bone coverage suggested that group A had significantly worst results.ConclusionsPorcine bone group had significantly better short-term outcomes with lower long-term maintenance of the buccal plate.

Sequential healing of the elevated sinus floor with different size of antrostomy: a histomorphometric study in rabbits.

To study the influence of the access window dimensions on the healing at the antrostomy and within the augmented maxillary sinus. A maxillary sinus augmentation was performed in twenty-four albino New Zealand rabbits. Antrostomies of 3 × 6 mm (small) or 5 × 6 mm (large) in dimensions were randomly prepared in each animal. A collagenated cortico-cancellous porcine bone was used to fill the elevated region, and an equine collagen membrane was placed on the antrostomies. Three different groups were formed, based on the time of euthanasia, i.e., 2, 4, and 8 weeks from surgery. No relevant changes of the height of the augmented sinus were detected over time. Mineralized bone increased between 2 and 4 weeks of healing while remained stable between 4 and 8 weeks. The highest amounts of new bone were found close to the sinus bone walls. No antrostomies were found healed with an even layer of corticalized bone, while large amounts of connective tissue were occupying the antrostomy in both groups. Antrostomies of different dimensions resulted in similar outcome in bone formation both in the antrostomy regions and within the elevated sinus.

Sinus Floor Elevation and Antrostomy Healing

To compare the histomorphometric outcomes of biopsies collected from the antrostomy and from the alveolar crest of the maxillary sinus after a sinus-lift procedure. In 12 volunteers, sinus floor elevation was performed using collagenated corticocancellous porcine bone. Nine months after the surgery, 2 biopsies, 1 from the alveolar crest and 1 from the antrostomy, were collected for histological analysis. Biopsies from 11 patients were available for histological analyses (n = 11). At the alveolar crest sites, the percentage of mineralized bone was 40.1 ± 14.1%, of bone marrow was 40.1 ± 18.0%, and of the xenograft was 14.7 ± 15.2%. Small amounts of soft tissue were found. At the antrostomy sites, the percentages of mineralized bone, bone marrow, and xenograft were 26.0 ± 10.8%, 23.4 ± 17.0%, and 28.2 ± 15.7%, respectively. Soft tissue was represented by 19.7 ± 19.4%. Higher amounts of mineralized bone and bone marrow were found in the alveolar crest compared with the antrostomy.

Influence of a collagen membrane positioned subjacent the sinus mucosa following the elevation of the maxillary sinus. A histomorphometric study in rabbits.

To evaluate the healing after elevation of the sinus mucosa when a collagen membrane was placed between the sinus mucosa and a xenograft used as filler. Eighteen rabbits were used. Sinus mucosa elevation was performed bilaterally, and a collagen membrane was applied subjacent to the sinus mucosa only at a randomly selected test site. At both sites, a collagenated corticocancellous porcine bone was placed within the elevated space and the access window was covered with a collagen membrane. The animals were sacrificed after 2, 4, and 8weeks of healing, six animals for group. Ground sections were prepared. At the histomorphometric evaluation, the elevated area after 2 and 8weeks was 11.8 and 8.8mm2 at the test, and 10.0 and 5.3mm2 at the control sites, respectively. The available area was obtained subtracting the remaining area occupied by the membrane from the elevated area and, after 8weeks, was 6.7±0.9mm2 . After 8weeks of healing, the mineralized new bone within the elevated space was 18.2±5.5% at the test and 26.7±7.7% at the control sites. Within the available space at the test site, the percentage was 27.3±7.0% after 8weeks of healing. At 2 and 8weeks of healing, within the elevated space, the xenograft proportion was 30.9±4.4% and 6.9±2.8% at the test, and 35.2±7.3% and 9.6±4.9% at the control sites, respectively. The placement of a collagen membrane subjacent the sinus mucosa did not reveal any major morphometric difference. The collagen membrane was not completely resorbed after 8weeks.

Regenerative properties of collagenated porcine bone grafts in human maxilla: demonstrative study of the kinetics by synchrotron radiation microtomography and light microscopy.

Recently, it has been reported that heterologous biomaterials, where the collagen matrix is preserved, seem to facilitate blood clotting and the subsequent invasion of repairing and regenerative cells. This study aimed at evaluating the healing of human extraction sockets grafted with a collagenated cortico-cancellous porcine bone (mp3®, OsteoBiol®, Tecnoss®, Giaveno, Italy) by synchrotron radiation X-ray microtomography (microCT) and histology in order to have a 3D quantitative characterization over time. Ridge preservation with porcine bone and collagen membrane was performed on 21 patients using a flapless approach and a secondary soft tissue closure. At the time of implant placement, six bone samples were harvested, two in the 3-month group, two in the 6-month group, one in the 12-month group post-surgery, and one spontaneously healed control, and evaluated by microCT and histology. MicroCT revealed that in the grafted sites there were a greater number of trabeculae, although they appeared thinner than in the control sites; these trabeculae homogenously filled the defects, suggesting an improved strength of the socket. Histology showed that over time, the amount of biomaterial decreased and the newly formed bone increased, while less dense bone with wider marrow spaces was detected in the control sample, supporting synchrotron findings. The morphometric data converge to indicate the suitability of porcine bone for the preservation of post-extraction sockets. The use of mp3 is encouraged to preserve and heal sockets.

Extra oral digital scanning and imaging superimposition for volume analysis of bone remodeling after tooth extraction with and without 2 types of particulate porcine mineral insertion: A randomized controlled trial.

Incorporation of bone substitute material into the extraction socket could minimize the edentulous ridge volume loss or maximize the bone formation within the healing area. The aim of the study was to test the effectiveness in maintaining the volumetric contour of fresh extraction sockets grafted with or without 2 types of porcine biomaterials and covered with a resorbable barrier. In the present multi-center single-blind randomized control trial, 55 patients underwent 1-tooth extraction, were surveyed, and randomly allocated to control- (25 sites, nat-group) or test groups (15 sites grafted with pre-hydrated collagenated cortico-cancellous porcine bone, coll-group, and 15 with cortical porcine bone, cort-group). Before extraction, and then 4 months later, contours of the sockets were acquired through a laser scanner, voxelized, and ghosts of each patient were superimposed with a matrix laboratory. Volumetric and area evaluations of the virtual superimposed models were performed with dentascan tools to create a volume of interest extending between the 2 residual teeth. Intra- and inter-group comparisons of the outcomes were performed. Non-parametric tests were applied with a level of significance set at P < .05. Intergroup analysis at 4 months' survey revealed that percentage loss of alveolar ridge volume of the coll-group (28.8% ± 8.8%) and of the cort-group (30.2% ± 7.1%) was significantly lower (P < .0001) than that of the naturally-healing group (46.4% ± 4.1%). No statistically-significant differences in outcomes were observed between the 2 test groups at any of the observation periods. Moreover, tooth position (bicuspids vs molars) seemed to affect neither volume loss nor basal shrinkage. At the 4-month analysis both test groups showed reduced bone loss when compared to naturally healing sockets. However, the 2 grafting materials were not able to preserve the alveolar crest, and a reduction close to 30% in the estimates was registered after healing.

Bactericidal efficacy of cold plasma in processed bone. A new approach for adjuvant therapy of medication-related osteonecrosis of the jaw?

BackgroundMedication-related osteonecrosis of the jaw is a difficult to treat side effect of antiresorptive therapy. Despite intensive efforts in the treatment of this disease, therapy continues to be prolonged, burdensome and sometimes insufficient. Since bacterial contamination of the necrotic bone is a major factor in these problems, we have examined the antibacterial effect of physical cold atmospheric pressure plasma on contaminated bone. MethodsA total of 72 cortico-cancellous porcine bone cylinders were processed and incubated in Streptococcus mitis broth and afterwards treated with cold atmospheric plasma, chlorhexidine or sodium chloride solution (control). After grinding up the specimens, the bacteria were transferred to aqueous solution and a colony-forming unit count was performed. ResultsPhysical cold atmospheric pressure plasma showed the best results in terms of reduction in colony-forming unit count in porcine bone: overall median in colony-forming unit/ml was significantly below that for chlorhexidine (p=0.004) and control (p=0.008). ConclusionThese results suggest that cold atmospheric pressure plasma has profound effectiveness on the bacterially contaminated bone in vitro. The use on cancellous bone is possibly a promising technique and could be a useful tool in the therapeutic range for the treatment of medication-related osteonecrosis of the jaw.

Postextractive implants in aesthetic areas: evaluation of perimplant bone remodeling over time

The aim of this research was to assess peri-implant bone remodeling of post-extractive implants over 2 years. 30 patients meeting pre-established inclusion criteria were enrolled for the study. One implant for each patient was inserted in the post-extraction sockets according to a defined surgical protocol (atramautic extraction, curettage of extraction socket, implant insertion, grafting with collagenated cortico-cancellous porcine bone, and a trimmed collagen membrane to completely cover the socket, suture). A temporary adhesive bridge, with an adequate profile, was bonded to the adjacent teeth. X-ray evaluation with a standardized stent was carried out at different times. Measurements were obtained from the implant edge to the bone peak. The values obtained at time 0 and at 2 years were compared by t-student test. Our results showed that after one year 73% of patient had 0 mm of bone reabsorption, 20% of patient had 0 mm ≤ x ≤ 0.5mm, 7% of patient had 0.5 mm ≤ x ≤ 2 mm of bone reabsorption. After two years 62% of patient had 0 mm of bone reabsorption, 24% had 0 mm ≤ x ≤ 0.5mm, 14% had 0.5 mm ≤ x ≤ 2 mm. The results showed no significant differences in bone reabsorption in most patients over 2 years.

Expression of SP7, RUNX1, DLX5, and CTNNB1 in human mesenchymal stem cells cultured on xenogeneic bone substitute as compared with machined titanium.

The aim of this research was to investigate the gene expression profile of 4 transcription factors in human mesenchymal stem cells (hMSC) cultured with a xenogeneic bone substitute and a support of machined titanium. In vitro studies were performed on hMSC cells, which grew in contact with cortical porcine bone and machined titanium disks for 10 days. RNA quantification for genes DLX5, CTNNB1, RUNX1, and SP7 was assessed by quantitative real-time polymerase chain reaction. For cells supported by titanium, immunocytochemistry of osteocalcin (OC) was also performed. In the osteoblast-induced cells (OIC), DLX5, CTNNB1, and RUNX1 were significantly upregulated (+2.38-, +3.51-, and +7.08-fold, respectively), whereas SP7 was downregulated (-26.32-fold). None of the genes seemed to be upregulated or downregulated by the corticocancellous porcine bone. In cells grown on titanium support, DLX5 and RUNX1 were respectively upregulated (+3.12-fold) and downregulated (-2.14-fold). For titanium support, the presence of both catenin beta-1 and OC was verified. The 2 genes RUNX1 and SP7 resulted differently expressed in cells cultured on metallic supports if compared with the expression recorded for OIC. An induction of the osteogenic phenotype was observed when cells were cultured on machined titanium, but not on xenogeneic material.

Tissue remodeling after bone expansion in grafted and ungrafted sockets.

The aim of this clinical study was to assess horizontal width changes in grafted and ungrafted sites after bone expansion and implant placement. Twenty-three patients were included in this prospective study. Each patient required extraction of two teeth and replacement with implants. After dental extraction in 23 alveoli (group 1), a collagen sponge was used to cover fresh sockets, and the remaining 23 alveoli (group 2) were grafted with corticocancellous porcine bone. Three months after extraction, bone expansion was performed in each site, and 46 dental implants were placed. To evaluate tissue volume changes, the variations in width of the buccal ridge were recorded with a periodontal probe immediately after tooth extraction, 3 months later (before implant placement), and 3 months after implant placement. In group 1, at 3 months after implant placement, mean volume changes of +1.6 ± 0.8 mm for incisors and canines, +1.4 ± 0.5 mm for premolars, and +0.8 ± 0.5 mm for molars were seen. In group 2, mean changes of +1.5 ± 0.8 mm for incisors and canines, +1.3 ± 0.3 mm for premolars, and +2.8 ± 0.6 mm for molars were observed. Statistically significant differences were found only for molars. In both groups, incisor, canine, and premolar sites showed no differences in volume changes, but statistically significant differences were found between molars in the two groups; the biomaterial graft prevented collapse of the large defects and significant volume loss.

Buccal bone deficiency in fresh extraction sockets: a prospective single cohort study

The purpose of this prospective single cohort study was to evaluate the use of xenograft and collagen membranes in treating full or partial buccal bone defects of fresh extraction sockets in the esthetic zone. Thirty-three patients requiring tooth extraction in the anterior maxillary area and showing a complete or partial buccal bone plate deficiency (more than 2 mm) were consecutively enrolled and treated. Corticocancellous porcine bone and platelet-rich fibrin (PRF) with a collagen membrane were used to graft the extraction sockets, and the membranes were left exposed to the oral cavity with a secondary soft tissue healing. The outcome variables were as follows: width of keratinized mucosa, facial soft tissue levels, clinical bone changes (measured with a clinical splint), implant and prosthesis failures, and peri-implant marginal bone changes. All treated sites allowed the placement of implants; the width of keratinized mucosa at the mid-facial aspect showed an increase of 2.3 mm 5 months after the grafting procedure, and its value was 3.2 ± 0.6 mm at 1-year follow-up. The mean values of the facial soft tissue level indicated an increase over time. The bone level showed an improvement of 0.8 ± 0.1 mm and 0.7 ± 0.1 mm at mesial and distal sites, respectively, when compared to the baseline measurements. Finally, in the palatal area, no bone changes were observed. No implant failed during the entire observation period. Findings from this study showed that xenograft and PRF, used for ridge preservation of the extraction sockets with buccal bone plate dehiscence in the esthetic zone, can be considered effective in repairing bone defects before implant placement. The secondary soft tissue healing over the grafted sockets did not compromise bone formation; moreover, the soft tissue level and the width of keratinized gingiva showed a significant improvement over time.

Dimensional alterations of extraction sites after different alveolar ridge preservation techniques – a volumetric study

The aim of this randomized controlled clinical study was to assess soft tissue contour changes after different alveolar ridge preservation procedures. Following tooth extraction, 30 patients were randomly assigned to the following treatments (Tx) - Tx 1: xenogenic bone substitute (pre-hydrated collagenated cortico-cancellous porcine bone) and free gingival graft; Tx 2: free gingival graft alone; Tx 3: xenogenic bone substitute; Tx 4: no further treatment (control). Impressions were obtained before tooth extraction (baseline) and 4 months after surgery. Cast models were optically scanned, digitally superimposed and horizontal measurements of the contour alterations between time points were performed using digital imaging analysis. All groups displayed contour shrinkage at the buccal aspect ranging from a mean horizontal reduction of -0.8±0.5mm (Tx 1) to -2.3±1.1mm (control). Statistically significant differences were found between Tx 1 and Tx 4 as well as Tx 2 and Tx 4. A significant positive influence of the free gingival graft on the maintenance of the ridge width was recorded (p<0.001). In this study, alveolar ridge preservation techniques were not able to entirely compensate for alveolar ridge reduction. Covering the orifice of the extraction socket with a free gingival tissue graft seems to have the potential to limit but not avoid the post-operative external contour shrinkage based on optical scans.

Simultaneous Sinus Augmentation with Implant Placement: Histomorphometric Comparison of Two Different Grafting Materials. A Multicenter Double-Blind Prospective Randomized Controlled Clinical Trial

Sinus elevation via the lateral approach for implant rehabilitation of atrophic posterior maxillae is considered a safe and predictable therapy. Several xenogeneic biomaterials of different biologic origin have been used as valid and predictable alternatives to autogenous bone. This multicenter randomized controlled double-blind prospective clinical trial aimed to compare histomorphometrically two xenogeneic grafting materials used for sinus elevation with simultaneous implant placement. Seven private practices in Italy were involved. Patients presenting at least one site with a residual bone crest height between 2 and 4 mm were treated. Control sites were grafted with 100% deproteinated particulated bovine bone (DPBB), while test sites were grafted with prehydrated corticocancellous porcine bone (PCPB). Root-form implants were placed simultaneously. Insertion torque and clinical stability were assessed and recorded. At 6 months, a biopsy specimen was harvested from each site, and histomorphometric analyses were performed. Thirty-seven patients received 42 sinus elevations (24 test and 18 control). Eighty-two implants with adequate primary stability were placed. Fifty-five implants were placed in residual bone crests greater than 2 mm but less than 4 mm (average 2.7 mm) and achieved an average insertion torque of 22.8 ± 11.3 N/cm. Nineteen implants were placed in ridges greater than 3 mm but less than 5 mm, and eight were placed in ridges with more than 5 mm remaining. After 6 months, three implants had failed to integrate, leading to a survival rate of 96.34%. Forty-two specimens were analyzed histomorphometrically. No significant differences in total bone volume (PCPB 37.43%, DPBB 37.52%) or residual grafting material (PCPB 13.55%, DPBB 16.44%) were detected. In this study, PCPB compared well with DPBB as a grafting material for lateral sinus elevation.

Tissue changes of extraction sockets in humans: a comparison of spontaneous healing vs. ridge preservation with secondary soft tissue healing

As a consequence of extraction, the height of the buccal wall tends to decrease and results in the disappearance of bundle bone. To modify bone remodelling after extraction, various ridge preservation techniques have been proposed. The present research was drawn up with the following considerations in mind: to evaluate and to compare changes of hard and soft tissues in post-extraction sockets which received a ridge preservation procedure, with post-extraction sockets which had healed naturally. Each patient was randomly allocated to a test or control group using a specific software package. After extraction, the sockets were carefully inspected and any granulation tissue was removed. The control sites received silk sutures to stabilize the clot without any grafting material. The test sites were grafted with corticocancellous porcine bone and a collagen membrane. All experimental sites had the membranes left exposed to the oral cavity with a secondary wound healing. The thickness of the buccal alveolar bone, if present, was carefully measured at the time of tooth extraction using a calliper at 1 mm from the edge of the wall. The following clinical parameters were evaluated at baseline and after 4 months at implant placement: vertical bone changes, horizontal bone changes and width of keratinized gingiva. The length, diameter and need for additional bone augmentation were assessed for both groups at the time of implant insertion. The control group showed vertical bone resorption of 1 ± 0.7 mm, 2.1 ± 0.6 mm, 1 ± 0.8 mm and 2 ± 0.73 mm at the mesial, vestibular, distal and lingual sites respectively. Moreover, changes in horizontal dimension showed an average resorption of 3.6 ± 0.72 mm. The test sites showed a horizontal bone remodelling of 0.3 ± 0.76 mm, 1.1 ± 0.96 mm, 0.3 ± 0.85 mm, 0.9 ± 0.98 mm at the mesial, vestibular, distal and lingual sites respectively. The horizontal bone resorption at the test sites was 1.6 ± 0.55 mm. The keratinized gingiva showed a coronal shift of 0.7 mm in the control group when compared to 1.1 mm in the test group. In addition, 42% of sites in the control group required an additional bone augmentation at implant placement, when compared to 7% in the test sites. This study clearly points out that an alveolar ridge preservation technique performed with collagenated porcine bone and a resorbable membrane--according to the procedure reported in this study--was able to limit the contour changes after tooth extraction. Finally, the test sites showed a better preservation of facial keratinized tissue when compared to control sites; grafted sites allowed the placement of longer and wider implants when compared to implants inserted in non-grafted sites.