Tomographic late evaluation of xenogeneic bone grafts in sockets of impacted third molars

Abstract It is necessary to preserve height and thickness of the alveolar bone to facilitate rehabilitation with osteointegratable implants or simply to maintain bone integrity after extraction. Biomaterials associated with resorbable or non-resorbable membranes, when placed in the region of the socket, may contribute to avoid this unwanted reabsorption. Objective The objective of this study was to evaluate the distance of the crest of alveolar ridge to the cementoenamel junction (CEJ) of the lower second molars and the bone density of the third molar socket filled with Gen-Tech®, 5 years after an exodontia using cone beam computed tomography (CBCT) to visualize the central region of the sockets, without overlapping of the buccal and lingual cortical bones. Material and Methods A total of 12 individuals from an initial group of 39 patients submitted to extraction of the unruptured lower third molars and grafting of an association of inorganic bovine bone matrix, organic bovine bone matrix, collagen and bone morphogenetic proteins (BMP) (Gen-Tech®) on one side and the contralateral sockets filled only by clot, returned to control after 5 years, and were submitted to CBCT. The distance from the crest of alveolar bone to the CEJ and the bone density (BD) were measured using the i-CAT Vision Software. Results The results showed that the distance from the crest of alveolar bone to the CEJ in the control group was similar to that observed before the exodontia; in the experimental group, this distance was smaller. Considering the BD measurement, a significantly higher density was observed in the experimental group (p<0.05). Conclusion Part of the biomaterial was not absorbed and allowed the stability of the evaluated parameters after 5 years, being able to be used as a bone substitute in the socket.

Alveolar bone healing in rats: micro-CT, immunohistochemical and molecular analysis

Abstract Alveolar bone healing after upper incisor extraction in rats is a classical model of preclinical studies. The underlying morphometric, cellular and molecular mechanism, however, remains imprecise in a unique study. Objectives The aim of this study was therefore to characterize the alveolar bone healing after upper incisor extraction in rats by micro computed tomographic (Micro-CT), immunohistochemical and real-time polymerase chain reaction (RT-PCR) analysis. Material and Methods Thirty animals (Rattus norvegicus, Albinus Wistar) were divided into three groups after upper incisors extraction at 7, 14, and 28 days. Micro-CT was evaluated based on the morphometric parameters. Subsequently, the histological analyses and immunostaining of osteoprotegerin (OPG), receptor activator of nuclear kappa B ligand (RANKL) and tartrate resistant acid phosphate (TRAP) was performed. In addition, RT-PCR analyses of OPG, RANKL, the runt-related transcription factor 2 (RUNX2), osteocalcin (OC), osteopontin (OPN), osterix (OST) and receptor activator of nuclear kappa B (RANK) were performed to determine the expression of these proteins in the alveolar bone healing. Results Micro-CT: The morphometric parameters of bone volume and trabecular thickness progressively increased over time. Consequently, a gradual decrease in trabecular separation, trabecular space and total bone porosity was observed. Immunohistochemical: There were no differences statistically significant between the positive labeling for OPG, RANKL and TRAP in the different periods. RT-PCR: At 28 days, there was a significant increase in OPG expression, while RANKL expression and the RANKL/OPG ratio both decreased over time. Conclusion Micro-CT showed the newly formed bone had favorable morphometric characteristics of quality and quantity. Beyond the RUNX2, OC, OPN, OST, and RANK proteins expressed in the alveolar bone healing, OPG and RANKL activity showed to be essential for activation of basic multicellular units during the alveolar bone healing.

Hyaluronic acid accelerates bone repair in human dental sockets: a randomized triple-blind clinical trial

Abstract This study evaluated the effects of hyaluronic acid (HA) on bone repair of human dental sockets. Thirty-two lower first premolars were extracted from 16 patients (2 per patient) for orthodontic reasons. Following the extractions, one socket was randomly filled with 1% HA gel, while the other was allowed to naturally fill with blood clot. After 30 and 90 days of surgery, patients underwent cone beam computed tomography. Five central orthoradial slices were captured from each socket. The gray intensity was measured in each image and results were reported as mean percentage of bone formation. The buccolingual alveolar ridge width was measured and dimensional changes were compared between the postoperative intervals. The pattern of alveolar trabecular bone was evaluated through the fractal dimension. Treated sockets showed a higher percentage of bone formation and fractal dimension values (58.17% and 1.098, respectively) compared with controls (48.97% and 1.074, respectively) in the 30-day postoperative period (p < 0.05). After 90 days, there was no significant difference between groups. Additionally, no significant difference was found between groups regarding the alveolar dimensions (p > 0.05). Use of 1% HA gel after tooth extraction accelerates bone repair in human dental sockets.

Diagnosis of alveolar and root fractures: an in vitro study comparing CBCT imaging with periapical radiographs

Abstract Objective To compare periapical radiograph (PR) and cone-beam computed tomography (CBCT) in the diagnosis of alveolar and root fractures. Material and Methods Sixty incisor teeth (20 higid and 40 with root fracture) from dogs were inserted in 60 anterior alveolar sockets (40 higid and 20 with alveolar fracture) of 15 macerated canine maxillae. Each fractured socket had a root fractured tooth inserted in it. Afterwards, each maxilla was submitted to PR in two different vertical angulation incidences, and to CBCT imaging with a small field of view (FOV) and high-definition protocol. Images were randomized and posteriorly analyzed by two oral and maxillofacial radiologists two times, with a two-week interval between observations. Results Sensitivity and specificity values were good for root fractures for PR and CBCT. For alveolar fractures, sensitivity ranged from 0.10 to 0.90 for PR and from 0.50 to 0.65 for CBCT. Specificity for alveolar fractures showed lower results than for root fractures for PR and CBCT. Areas under the ROC curve showed good results for both PR and CBCT for root fractures. However, results were fair for both PR and CBCT for alveolar fractures. When submitted to repeated measures ANOVA tests, there was a statistically significant difference between PR and CBCT for root fractures. Root fracture intraobserver agreement ranged from 0.90 to 0.93, and alveolar fracture intraobserver agreement ranged from 0.30 to 0.57. Interobserver agreement results were substantial for root fractures and poor/fair for alveolar fractures (0.11 for PR and 0.30 for CBCT). Conclusion Periapical radiograph with two different vertical angulations may be considered an accurate method to detect root fractures. However, PR showed poorer results than CBCT for the diagnosis of alveolar fractures. When no fractures are diagnosed in PR and the patient describes pain symptoms, the subsequent exam of choice is CBCT.

Dimensions for midline and paramidline andibulotomy: a radiographic study in the dentate Thai population.

BACKGROUND: Mandibulotomy is an important surgical approach of the oral cavity, oropharynx, and parapharyngeal space. OBJECTIVE: To provide dimensions for placement of bone cuts for midline (between two central incisors) and paramidline (between lateral incisor and canine) mandibulotomy. MATERIAL AND METHOD: Two hundred and sixteen periapical radiographs with the mandibular anterior teeth of 72 healthy Thai dental patients (30 males, 42 females) were selected. The angles between the long axes of the two central incisors (M) and between the lateral incisor and canine (PM) were bilaterally measured using computerized imaging. The horizontal distances (at crestal, middle, and apical levels) between the roots and the alveolar bone heights of the aforementioned teeth were also measured. RESULTS: The angles between the PM (0.00-9.26 degrees) were less convergent than those between the M (0.00-11.66 degrees) (p < 0.05). The distances between the PM were 0.60-8.03 mm, whereas those between the M were 0.47-6.63 mm (p < 0.05). Mean alveolar bone height is 15.88 +/- 1.72 mm in the canine. CONCLUSION: The paramidline mandibulotomy is done in a wider space than the midline cut and could have a better chance to avoid the extraction of a central incisor and preserve the origin of the genioglossus, geniohyoid, and digastric muscles.