Histologic wound healing in studies using different ridge preservation protocols: A review.

BACKGROUND: Alveolar ridge preservation (ARP) procedures are designed to lessen dimensional changes in the alveolar ridge after tooth extraction. Wound healing after ridge preservation involves the formation of new vital bone in the former socket, and this vital bone is important in the osseointegration of dental implants. METHODS: A series of ARP studies have been performed to help clinicians better understand the wound-healing events that occur following tooth extraction and ridge preservation. Different protocols have been examined using various materials and periods of healing time prior to implant placement. The primary aim of these studies was to ascertain the relative percentage of vital bone formation, residual graft material, and connective tissue (CT)/other at the healing site using histomorphometric examination of bone core biopsies obtained during osteotomy preparation. RESULTS: For allografts, the use of demineralized bone alone or in combination with mineralized is associated with more vital bone formation than the use of mineralized allograft alone. For mineralized allografts, the use of cortical versus cancellous bone has only minimal impact on new bone formation. Xenografts from bovine and porcine sources appear to have similar vital bone formation. Longer healing times prior to implant placement are associated with increased vital bone formation and decreased residual graft material. The most stable component in most studies is the percentage of CT/other. CONCLUSIONS: The percentage of vital bone and residual graft at ARP sites is dependent on the materials used and the length of healing time prior to obtaining core biopsies. KEY POINTS: What factors may affect the amount of new bone at the ARP site? At a time point about 4 months after ARP, the type of graft material used for ARP plays a large role in new bone formation. Studies focus on means and standard deviations, but patients often do not "follow the mean." Even if a single ARP protocol is used for all patients, there is great interindividual variability in new bone formation, and there is often variability between sites within a single patient. How long after ARP with an allograft should I wait to place an implant? Longer healing times such as 4-5 months generally provide higher amounts of vital bone formation than shorter healing times like 2-3 months. Differences in vital bone formation between ARP protocols tend to decrease with longer healing time. FDBA that contains demineralized bone, either alone or combined with mineralized FDBA, often provides higher amounts of new bone formation than 100% mineralized allograft, especially at shorter healing periods. Even a year after ARP with an allograft, residual graft material is often still present at the ARP site.

A radiographic and histological study to compare red (650 nm) versus near infrared (810 nm) diode lasers photobiomodulation for alveolar socket preservation.

Previous findings indicated that the laser photobiomodulation is more effective than the control or placebo in preserving the alveolar socket. This study aimed to compare two different lasers regarding their effectiveness in aiding alveolar socket preservation. Twenty extraction sockets were selected then divided into two equal groups. Group A was exposed to 650 nm Diode laser, and Group B to 810 nm Diode laser following the same protocol and parameters after a standard alveolar socket preservation procedure with collagen plug. Radiographic analysis with cone beam computed tomography was done to compare the alveolar bone surface area immediately after extraction and three months post-operatively, while bone samples collected before implant drilling were histologically examined for newly formed bone evaluation and histomorphometric analysis in terms of percentage of new bone surface area, percentage of unmineralized bone and finally, immunohistochemical analysis of Osteocalcin reaction surface area as well as optical density. Radiographically, infrared (810 nm) Diode effect on alveolar bone surface area has significantly exceeded the red laser, while histologically, red (650 nm) Diode has demonstrated statistical significance regarding all parameters; newly formed bone surface area percentage, unmineralized bone area percentage and finally Osteocalcin bone marker reaction surface area percentage and optical density. Under the specified conditions and laser parameters, photobiomodulation using the 810 nm Diode got the upper hand radiographically, yet histologically, the red 650 nm Diode managed to dominate all histological parameters when both employed as an adjunct to alveolar socket preservation procedures.

Comparison of different bone substitutes in the repair of rat calvaria critical size defects: questioning the need for alveolar ridge presentation.

OBJECTIVE: This study aimed to evaluate the effectiveness of biomaterials in bone healing of critical bone defects created by piezoelectric surgery in rat calvaria. METHOD AND MATERIALS: Histomorphologic analysis was performed to assess bone regeneration and tissue response. Fifty animals were randomized into five groups with one of the following treatments: Control group (n = 10), spontaneous blood clot formation with no bone fill; BO group (Bio-Oss, Geistlich Pharma; n = 10), defects were filled with bovine medullary bone substitute; BF group (Bonefill, Bionnovation; n = 10), defects were filled with bovine cortical bone substitute; hydroxyapatite group (n = 10), defects were filled with hydroxyapatite; calcium sulfate group (n = 10), defects were filled with calcium sulfate. Five animals from each group were euthanized at 30 and 45 days. The histomorphometry calculated the percentage of the new bone formation in the bone defect. RESULTS: All data obtained were evaluated statistically considering P < .05 as statistically significant. The results demonstrated the potential of all biomaterials for enhancing bone regeneration. The findings showed no statistical differences between all the biomaterials at 30 and 45 days including the control group without bone grafting. CONCLUSION: In conclusion, the tested biomaterials presented an estimated capacity of osteoconduction, statistically nonsignificant between them. In addition, the selection of biomaterial should consider the specific clinical aspect, resorption rates, size of the particle, and desired bone healing responses. It is important to emphasize that in some cases, using no bone filler might provide comparable results with reduced cost and possible complications questioning the very frequent use of ridge presentation procedures.

Alveolar ridge preservation of two-wall bone defects using mineralized dentin matrix: An experimental pre-clinical study.

OBJECTIVES: To study bone healing of two-wall bone defects after alveolar ridge preservation using mineralized dentin matrix. MATERIALS AND METHODS: After distal roots extraction of second and fourth premolars (P2, P4) on one lateral mandible in 12 beagles, two-wall bone defects (5 × 5 × 5 mm) were surgically created distally to the remaining mesial roots of P2 and P4. A total of 24 sites were randomly allocated to three groups (implant material- time of execution): mineralized dentin matrix (MDM)-3 m (MDM + collagen membrane; 3 months), MDM-6 m (MDM particles + collagen membrane; 6 months), and C-6 m (collagen membrane only; 6 months). Clinical, radiographic, digital, and histological examinations were performed 3 and 6 months after surgery. RESULTS: The bone healing in MDM groups were better compared to Control group (volume of bone regenerated in total: 25.12 mm3 vs. 13.30 mm3, p = .046; trabecular volume/total volume: 58.84% vs. 39.18%, p = .001; new bone formation rate: 44.13% vs. 31.88%, p = .047). Vertically, the radiological bone level of bone defect in MDM-6 m group was higher than that in C-6 m group (vertical height of bone defect: 1.55 mm vs. 2.74 mm, p = .018). Horizontally, no significant differences in buccolingual bone width were found between MDM and C groups at any time or at any level below the alveolar ridge. The percentages of remaining MDM were <1% in both MDM-3 m and MDM-6 m groups. CONCLUSIONS: MDM improved bone healing of two-wall bone defects and might be considered as a socket fill material used following tooth extraction.

Clinical outcomes following atrophic alveolar ridge reconstruction using collagenated xenogeneic bone block or autogenous bone block: One-year follow-up of a randomized controlled clinical.

AIM: This investigation aimed to evaluate the 1-year survival of implants placed after staged lateral alveolar ridge augmentation using equine-derived collagenated xenogeneic bone blocks (CXBBs) or autogenous bone block (ABB). MATERIALS AND METHODS: Fifty patients who underwent lateral augmentation in a previous trial were included. The primary outcome measure was implant survival at the 1-year follow-up, and secondary outcomes included implant success, peri-implant clinical and volumetric parameters, pink aesthetic scores (PES) and patient-reported outcome measures. Data analysis involved Fisher's exact test, the Mann-Whitney U-test and the Wilcoxon signed-rank test. RESULTS: In this study, no late implant failures were observed. The cumulative survival rates were 78.6% for the CXBB group and 90.9% for the ABB group, with no difference between the groups. Similarly, the success rates were 53.6% and 63.6%, respectively, showing no significant difference. Peri-implant clinical and volumetric parameters indicated the presence of healthy peri-implant tissues surrounding implants placed in both CXBB- and ABB-augmented sites. PES were 8.5 and 11.0 for implants placed in CXBB- and ABB-augmented sites, respectively. Furthermore, patient satisfaction rates were high and similar between the groups. CONCLUSIONS: Dental implants placed in both CXBB- and ABB-augmented ridges demonstrated no statistically significant differences in clinical, volumetric and aesthetic outcomes, along with high patient satisfaction rates.

Injectable platelet rich fibrin versus hyaluronic acid with bovine derived xenograft for alveolar ridge preservation. A randomized controlled clinical trial with histomorphometric analysis.

BACKGROUND: Alveolar ridge preservation (ARP) is a technique that aims to maintain bone volume and minimize resorption after tooth extraction. OBJECTIVE: This study aimed to compare the effectiveness of injectable platelet-rich fibrin (I-PRF) versus hyaluronic acid (HA) in combination with xenografts for ARP. METHODS: This randomized controlled trial included 36 patients (20 females and 16 males) who required implant placement in the upper arch. The patients were randomly allocated to one of three groups (n = 12 each): I-PRF with xenografts, HA with xenografts, or xenografts alone. All patients underwent ARP, and the extraction sockets were sealed with a free gingival graft harvested from the palate, a total of 36 implants were inserted. Cone-beam CT scans were performed before and 4 months postoperatively to measure radiographic bone gain as the primary outcome. Clinical parameters, including soft tissue thickness and clinical bone width, were evaluated preoperatively, and at 4 months and 1 year postoperatively. Additionally, histological assessment of core bone biopsies was performed 4 months postoperatively using histomorphometric analysis to determine the percentages of newly formed bone, mature bone, and residual grafts. RESULTS: Regarding the radiographic bone gain 4 months postoperative the HA group exhibited the highest value (9.78 ± 0.87), which was significantly greater than the values observed in the I-PRF and control groups (8.60 ± 1.27 and 7.99 ± 0.89, respectively) (one-way ANOVA, p = 0.007). Crestal bone loss was significantly higher in the control group (-0.98 ± 0.18) than in the I-PRF group (-0.53 ± 0.11) and HA group (-0.33 ± 0.15) groups (one-way ANOVA, p < 0.001). In the histomorphometric analysis, the mean area fraction of newly formed bone trabeculae was significantly higher in the HA group (56.66 ± 7.35) than in the I-PRF group (28.74 ± 5.15) and the control group (24.05 ± 3.64) (repeated measures ANOVA, p < 0.001). Additionally, the mean area fraction of residual graft material was higher in the I-PRF group (6.76 ± 2.59), followed by the control group (2.71 ± 1.24), while the HA group had the lowest value (2.63 ± 1.27) (Repeated measures ANOVA, p < 0.001). CONCLUSION: The combination of HA with xenografts yielded better radiographic and histological outcomes in terms of new bone formation and degree of bone maturation than the I-PRF and control groups. Furthermore, I-PRF improved soft tissue thickness. Please note that clinical trial registration was not completed prior to participant recruitment and randomization. The registration link for this trial is https://clinicaltrials.gov/ct2/show/NCT05781529.

Horizontal ridge augmentation with particulate cortico-cancellous freeze-dried bone allograft alone or combined with injectable-platelet rich fibrin in a randomized clinical trial.

OBJECTIVES: The objective of this study is to assess the effectiveness of horizontal ridge augmentation using FDBA in combination with injectable-platelet rich fibrin (i-PRF) versus FDBA alone. To fulfill this aim, the radiographic and histomorphometric outcomes are compared. METHOD: The study involved 41 patients who had horizontal alveolar ridge defects categorized as either B (2.5-7 mm) or C (0-2.5 mm). The control group received FDBA alone (n = 20), while the test group received FDBA in combination with i-PRF (n = 21). The horizontal dimensions of the alveolar ridge were measured at 0, 2, 4, and 6 mm from the bone crest using CBCT before and 6 months after alveolar ridge augmentation. In the second-stage surgery, 24 biopsies were taken from the augmented bone - 13 from the control group and 11 from the test group, and were examined histologically and histomorphometrically. The data were analyzed using Pearson correlation coefficient, chi-square, paired-t, and two-sample t tests. RESULTS: There was no significant difference (p > 0.05) in the increase of mean ridge width between the test group and the control group after 6 months at distances of 0, 2, 4, and 6 mm from the crest, with differences of -0.28, 0.12, 0.52, and 1.04 mm, respectively. However, the amount of newly formed bone and material residues was significantly higher in the FDBA + i-PRF group compared to the FDBA alone group (45.01% and 13.06% vs 54.03% and 8.48%, respectively). There was no significant difference in the amount of soft tissue between the two groups (41.02% and 37.5%, p > 0.05). CONCLUSION: The study found that there was no statistically significant difference in the increase of horizontal ridge width between the FDBA + i-PRF group and the FDBA group. However, the histomorphometric analysis revealed that the FDBA + i-PRF group had a higher proportion of newly formed bone, less connective tissue, and fewer residual particles. This suggests a superior quality of bone formation compared to the FDBA group.

The impact of immediate versus delayed mini-screw placement on alveolar bone preservation and bone density following tooth extraction: evidence from a canine model.

The aim of this study was to evaluate the impact of mini-screw placement on the alveolar ridge using a split-mouth design. Twelve beagles underwent bilateral extraction of their lateral teeth. In the immediate group, a mini-screw was unilaterally placed approximately 3-4 mm below the alveolar crest of the extraction site on the experimental side. The delayed group received mini-screws six weeks after tooth extraction. On average, the dogs were sacrificed after 11 weeks, and the maxillary bones were excised and scanned using cone-beam computed tomography (CBCT). Histopathological examinations were conducted to assess inflammation and bone formation scores. The results showed that in the immediate group, bone height was significantly greater on the intervention side compared to the control side (p < 0.05), whereas there was no significant difference in the delayed group. In both groups, there was a significant increase in bone density around the mini-screws compared to the control sides (p < 0.05). Mini-screw insertion led to a significant enhancement of bone growth in both groups (p < 0.05), with no notable differences between the two groups. The mini-screws did not have any impact on bone inflammation or width. Overall, both immediate and delayed mini-screw placement in the extraction socket positively influenced bone dimensions, density, and histological properties. However, immediate insertion was more effective than delayed placement in preserving vertical bone height, despite delayed insertion resulting in higher bone density.

Demineralized dentin matrix promotes gingival healing in alveolar ridge preservation of premolars extracted for orthodontic reason: a split-mouth study.

Objective: The purpose of this study was to prospectively evaluate the efficacy of a demineralized dentin matrix (DDM) in decreasing the initial inflammatory response of the gingiva and facilitating the repair and regeneration of soft tissue in alveolar ridge preservation. Methods: This clinical study employed a split-mouth design. Fourteen patients with a total of forty-four sites underwent extraction and alveolar ridge preservation (ARP) procedures. A Bilaterally symmetrical extraction operation were conducted on the premolars of each patient. The experimental group received DDM as a graft material for ARP, while the control group underwent natural healing. Within the first month postoperatively, the pain condition, color, and swelling status of the extraction sites were initially assessed at different time points Subsequently, measurements were taken for buccal gingival margin height, buccal-lingual width, extraction socket contour, and the extraction socket area and healing rate were digitally measured. Additionally, Alcian Blue staining was used for histological evaluation of the content during alveolar socket healing. Results: Both groups experienced uneventful healing, with no adverse reactions observed at any of the extraction sites. The differences in VAS pain scores between the two groups postoperatively were not statistically significant. In the early stage of gingival tissue healing (3 days postoperatively), there were statistically significant differences in gingival condition and buccal gingival margin height between the two groups. In the later stage of gingival tissue healing (7, 14, and 30 days postoperatively), there were statistically significant differences in buccal-lingual width, extraction socket healing area, and healing rate between the two groups. Furthermore, the histological results from Alcian Blue staining suggested that the experimental group may play a significant role in promoting gingival tissue healing, possibly by regulating inflammatory responses when compared to the control group. Conclusion: The application of DDM in alveolar ridge preservation has been found to diminish initial gingival inflammation after tooth extraction. Additionally, it has shown the ability to accelerate early gingival soft tissue healing and preserve its anatomical contour. Clinical trial registration: chictr.org.cn, identifier ChiCTR2100050650.

Evaluation of alveolar ridge preservation in sockets with buccal dehiscence defects using two types of xenogeneic biomaterials: An in vivo experimental study.

OBJECTIVES: Alveolar ridge preservation (ARP) has been extensively investigated in various preclinical and clinical studies, yielding favorable results. We aim to evaluate the effects of ARP using collagenated bovine bone mineral (CBBM) alone or particulated bovine bone mineral with a non-cross-linked collagen membrane (PBBM/NCLM) in tooth extraction sockets with buccal dehiscence in an experimental dog model. MATERIALS AND METHODS: The mesial roots of three mandibular premolars (P2, P3, and P4) were extracted from six mongrel dogs 4 weeks after inducing dehiscence defects. ARP was randomly performed using two different protocols: 1) CBBM alone and 2) PBBM/NCLM. Three-dimensional (3D) volumetric, micro-computed tomography, and histological analyses were employed to determine changes over a span of 20 weeks. RESULTS: In 3D volumetric and radiographic analyses, CBBM alone demonstrated similar effectiveness to PBBM/NCLM in ARP (p > .05). However, in the PBBM/NCLM group (3.05 ± 0.60 mm), the horizontal ridge width was well maintained 3 mm below the alveolar crest compared with the CBBM group (2.11 ± 1.01 mm, p = .002). CONCLUSION: Although the radiographic changes in the quality and quantity of bone were not significant between the two groups, the use of PBBM/NCLM resulted in greater horizontal dimensions and more favorable maintenance of the ridge profile.

Alveolar Ridge Preservation Procedures Performed with a Freeze-Dried Bone Allograft: Histologic Outcomes in a Cohort Study.

The primary aim of this study was to assess the histomorphometric outcomes of extraction sockets grafted with freeze-dried bone allograft (FDBA) and sealed with a collagen membrane after 3 months of healing in specific region of interest (ROI) areas. The secondary aims were to analyze the biomaterial resorption rate, the bone-to-biomaterial contact (BBC), and the area and perimeter of grafted particles compared with commercially available FDBA particles. Fifteen patients underwent tooth extractions and ridge preservation procedures performed with FDBA and a collagen membrane. Bone biopsy samples were harvested after 3 months at the time of implant placement for histologic and histomorphometric analysis. Two areas of concern (ROI1 and ROI2) with different histologic features were identified within the biopsy samples; ROI1, ROI2, and commercially available particles were analyzed and compared. The following parameters were analyzed: newly formed bone, marrow space, residual graft particles, perimeter and area of FDBA particles, and BBC. The histomorphometric analysis showed 35.22% ± 10.79% newly formed bone, 52.55% ± 16.06% marrow spaces, and 12.41% ± 7.87% residual graft particles. Moreover, the histologic data from ROI1 and ROI2 showed that (1) the mean percentage of BBC was 64.61% ± 27.14%; (2) the newly formed bone was significantly higher in ROI1 than in ROI2; (3) the marrow space was significantly lower in ROI1 than in ROI2; and (4) the FDBA particles in ROI1 sites showed significantly lower area and perimeter when compared to commercially available FDBA particles. This latter data led to the hypothesis that FDBA particles embedded in newly formed bone undergo a resorption/remodeling process.

Evaluation of maxillary palatal process pneumatization by cone-beam computed tomography.

PURPOSE: The aim of this study is to investigate the pneumatization type of the palatal process (PTP) and angular and distance measurements of neighbouring structures on cone beam computed tomography (CBCT) images. MATERIALS AND METHODS: 400 maxillary sinuses (MS) of 200 patients (96 female; 104 male; mean age: 43.2) were retrospectively evaluated. PTP was divided into three as types 1,2 and 3 and evaluated at distances 4, 8, 16, and 24 mm posterior to incisive foramen. The sinus and alveolar ridge height, palatonasal recess angle (PRA) and palatal junction angle (PJA) were also measured and recorded. RESULTS: PTP I (101, 25.3%) was the most frequent type, followed by PTP II (95, 23.8%), and the least was PTP III (4, 1%). In patients with PTP I, the alveolar ridge height in the 4 mm and 8 mm group was significantly higher than in the patients with PTP II and III (p<0.05). In patients with PTP I, PRA in the 4 mm and 16 mm groups was significantly higher than in patients with PTP II and III (p<0.05). Sinus and alveolar ridge height, PRA and PJA did not differ significantly between the right and left sides in the 4 mm, 8 mm, 16 mm, and 24 mm groups (p>0.05). CONCLUSION: Knowing the anatomy of the MS is very important for a successful surgical procedure in this area. Anatomy and pathology of the MS can be understood more clearly in CBCT.

Three-dimensional relationships between condylar volume and dentoskeletal characteristics in Class II hyperdivergent female adults.

BACKGROUND: This study aimed to determine the differences among various volumes of condylar osseous patterns and the corresponding dentoskeletal characteristics based on the risk of temporomandibular disorder. METHODS: Craniofacial spiral computed tomography data of 60 Class II hyperdivergent female adults were divided into normal, resorptive, flattened, and osteophyte groups based on condylar osseous forms. The condylar volumes of each group were compared, and their correlations with the dentoskeletal characteristics were assessed in three dimensions. Pairwise least significant difference tests were used to examine individual pairwise differences between groups, and one-way analysis of variance was used to measure differences among multiple groups. Pearson correlation and Spearman rank correlation analyses were used to determine the correlation between condylar volume and dentofacial characteristics. Statistical significance was established at p < 0.05. RESULTS: The condylar volume in the normal group was significantly greater than that in the changed groups, with no significant differences between the subgroups. The decrease in condylar volume was associated with a retruded and clockwise-rotated mandible with shorter rami. Condylar volume was negatively correlated with overjet, the alveolar height of the lower anterior and posterior teeth, sagittal inclinations of the lower teeth, intermolar width of the mandibular first molars, and width between the corresponding alveolar crests. CONCLUSION: Multiple three-dimensional dentoskeletal characteristics of Class II hyperdivergent female adults are correlated with condylar bony changes, regardless of the form. These results could be helpful in indicating potential pathological changes in the temporomandibular joint and in making proper treatment plans for these patients.

The Use of Cancellous Block Allografts for Reconstruction and Following Implant Failure Associated with Severe Bone Loss: A Prospective Survival and Histomorphometric Study.

A failed implant site is prone to reduced alveolar bone volume, both horizontally and vertically. The present study assessed the outcome of using cancellous bone block allografts for ridge reconstruction following the removal of failed implants associated with severe bone loss. Individuals presenting with failed implants and massive bone loss were included. Cancellous bone block allografts were used for reconstruction of the atrophic alveolar ridge. Radiographic evaluation at 6 months postgrafting revealed favorable bone healing, allowing implant placement. Bone biopsy samples were taken during implant placement. Twenty-four blocks and 58 implants were placed in 16 patients. Over a mean follow-up time of 40 ± 15 months, the mean bone gain was 5 ± 0.5 mm horizontally and 7 ± 0.5 mm vertically. Block and implant survival rates were 96% (1 block failed) and 95% (3 implants failed), respectively. Histomorphometrically, the mean percentage of newly formed bone was 40%, with 20% residual cancellous block allograft and 40% marrow and connective tissue. Cancellous bone block allograft is a viable treatment alternative for reconstructing the alveolar ridge to achieve a successful second reimplantation, even in the presence of initial severe bone loss.

Current perspectives of residual ridge resorption: Pathological activation of oral barrier osteoclasts.

PURPOSE: Tooth extraction is a last resort treatment for resolving pathological complications of dentition induced by infection and injury. Although the extraction wound generally heals uneventfully, resulting in the formation of an edentulous residual ridge, some patients experience long-term and severe residual ridge reduction. The objective of this review was to provide a contemporary understanding of the molecular and cellular mechanisms that may potentially cause edentulous jawbone resorption. STUDY SELECTION: Clinical, in vivo, and in vitro studies related to the characterization of and cellular and molecular mechanisms leading to residual ridge resorption. RESULTS: The alveolar processes of the maxillary and mandibular bones uniquely juxtapose the gingival tissue. The gingival oral mucosa is an active barrier tissue that maintains homeostasis of the internal organs through its unique barrier immunity. Tooth extraction not only generates a bony socket but also injures oral barrier tissue. In response to wounding, the alveolar bone socket initiates regeneration and remodeling through coupled bone formation and osteoclastic resorption. Osteoclasts are also found on the external surface of the alveolar bone, interfacing the oral barrier tissue. Osteoclasts in the oral barrier region are not coupled with osteoblastic bone formation and often remain active long after the completion of wound healing, leading to a net decrease in the alveolar bone structure. CONCLUSIONS: The novel concept of oral barrier osteoclasts may provide important clues for future clinical strategies to maintain residual ridges for successful prosthodontic and restorative therapies.

Restoring the electrical microenvironment using ferroelectric nanocomposite membranes to enhance alveolar ridge regeneration in a mini-pig preclinical model.

The maintenance and incremental growth of the alveolar bone at the tooth extraction site, to achieve the required height and width for implant restoration, remains a major clinical challenge. Here, the concept of restoring the electrical microenvironment to improve the effects of alveolar ridge preservation (ARP) was investigated in a mini-pig preclinical model. The endogeneous electrical microenvironment of the dental alveolar socket was recapitulated by fabricating a biomimetic ferroelectric BaTiO3/poly(vinylidene fluoridetrifluoroethylene) (BTO/P(VDF-TrFE)) non-resorbable nanocomposite membrane polarized by corona poling. The polarized nanocomposite membrane exhibited excellent electrical stability. After implantation with bone grafts and covering with the charged membrane in tooth extraction sites for three months, both the vertical and horizontal dimension resorption of the alveolar ridge were significantly prevented, as assessed by cone beam computed tomography (CBCT) analyses. Micro-CT analysis showed that the charged membrane induced significant enhancement of newly regenerated bone at the tooth extraction sites. Histological analysis further confirmed that the restoration of the electrical microenvironment significantly promoted buccal alveolar bone regeneration and maturation. In addition, the charged membranes can maintain their structural integrity during the entire implantation period and exhibit positive long-term systemic safety, as assessed by preclinical sub-chronic systemic toxicity. These findings thus provide an innovative strategy for restoring the electrical microenvironment to enhance ARP following dentition defect and edentulism, which could further advance prosthodontics implant technology.

Prognostic factors from squamous cell carcinoma of the hard palate, gingiva and upper alveolar ridge.

The purpose of this study was to evaluate the clinicodemographic characteristics and treatment protocol as prognostic factors in patients with oral squamous cell carcinoma (OSCC) of the hard palate, upper gingiva, and alveolar ridge (HPUGAR). This retrospective cohort study collected data of patients treated in two head and neck surgery departments in southern Brazil between 1999 and 2021. Information on clinicodemographic data, habits, site, size, clinical aspect, clinical staging, cervical metastasis, treatment, and survival was collected. Associations between independent variables and outcomes were assessed using Pearson's chi-square test and binary regression. Kaplan-Meier test was employed to compare the survival between the neck approaches. Forty-one patients were included; most were male (61%), with a mean age of 68.8 (± 13.9) years. The consumption of tobacco (p = 0.003) and alcohol (p = 0.02) was significantly higher in male than in female patients. The main clinical features observed in the study sample were lesions larger than 2 cm (48.7%), no cervical (90.2%), or distant metastasis (90.2%). Surgery alone was the main treatment approach (48.8%). The watch-and-wait strategy was adopted in 34 cases (83.0%), while elective neck dissection was applied in five (12.2%). Only two patients with cN0 disease (4.9%) presented with cervical metastasis at follow-up. Eight patients (12.2%) died of the disease. Clinicodemographic variables, habits, surgical margins, and histological subtype were not significantly associated with cervical metastasis or survival. Cervical metastasis (p = 0.004) was associated with poor survival. No difference was detected in survival between different neck approaches (p = 0.28). Cervical metastasis and local recurrence are negative prognostic factors for HPUGAR OSCC.

Use of Autogenous Tooth-Derived Mineralized Dentin Matrix in the Alveolar Ridge Preservation Technique: Clinical and Histologic Evaluation.

This study clinically and histologically evaluated the new bone formation and soft tissue changes when an autogenous tooth-derived mineralized dentin matrix (DDM) graft covered with a free gingival graft (FGG) was used for alveolar ridge preservation, as compared to spontaneous healing. Using a split-mouth protocol, 14 consecutive patients who required two extractions of a single-rooted tooth in the maxillary arch were enrolled. In each patient, one extraction site was treated with DDM and FGG (test group), while the other extraction site was covered with FGG and healed spontaneously (control group). In both test and control sites, implant placement was performed after a 16-week healing period. Compared to baseline (immediately after tooth extraction), both treatments yielded statistically significant differences in some clinical parameters and in the bone micro-architecture within the augmented sites. However, the use of DDM with the FGG created greater new vital bone formation, more newly formed bone, and fewer dimensional tissue changes than spontaneous healing with FGG.

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

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

Alveolar bone response distal to applied orthodontic forces in ovariectomized rats.

OBJECTIVES: The aim of this study was to investigate the effect of the application of orthodontic tooth forces on the alveolar bone distal to the loaded teeth, in ovariectomized female rats. METHODS: Twenty-four eight-month-old Wistar rats were divided into one group ovariectomized at the age of six months and one control. An orthodontic appliance delivering a mesial traction force of 60 gr* was placed on the right maxillary 1st molar of all animals for 14 days. Histology of the alveolar bone, of the adjacent and distal teeth to the loaded molar and the contralateral side, was performed following euthanasia. RESULTS: In the non-ovariectomized rats, extensive resorption was noticed in the direction of the orthodontic movement in the 2nd and 3rd molar interdental space, whereas the respective contralateral interdental space did not show any remodeling activity. Ovariectomized rats displayed reduced osseous tissue in the interdental space of both sides. The alveolar bone in the interradicular area of the 2nd loaded molar revealed frontal resorption, whereas, the alveolar interradicular bone of the contralateral 2nd molar showed internal resorption. CONCLUSIONS: In conclusion, orthodontic forces applied to the dentoalveolar complex of ovariectomized rats affect bone remodeling, even in areas distal to the site of force application. This finding should be taken into account during orthodontic treatment of women during menopause.