Comparative effects of photobiomodulation therapy at wavelengths of 660 and 808 nm on regeneration of inferior alveolar nerve in rats following crush injury.

The aim of the present study was to investigate the therapeutic effects of 660-nm and 880-nm photobiomodulation therapy (PBMT) following inferior alveolar nerve (IAN) crush injury. Following the nerve crush injuries of IAN, 36 Wistar rats were randomly divided into three groups as follows: (1) control, (2) 660-nm PBMT, and (3) 808-nm PBMT (GaAlAs laser, 100 J/cm2, 70 mW, 0.028-cm2 beam). PBMT was started immediately after surgery and performed once every 3 days during the postoperative period. At the end of the 30-day treatment period, histopathological and histomorphometric evaluations of tissue sections were made under a light and electron microscope. The ratio of the inner axonal diameter to the total outer axonal diameter (g-ratio) and the number of axons per square micrometer were evaluated. In the 808-nm PBMT group, the number of nerve fibers with suboptimal g-ratio ranges of 0-0.49 (p < 0.001) is significantly lower than expected, which indicates better rate of myelinization in the 808-nm PBMT group. The number of axons per square micrometer was significantly higher in the 808-nm PBMT group when compared with the control (p < 0.001) and 660-nm PBMT group (p = 0.010). The data and the histopathological investigations suggest that the PBMT with the 808-nm wavelength along with its settings was able to enhance IAN regeneration after nerve crush injury.

Evaluation of the Effects of Low-Level Laser Therapy on Diabetic Bone Healing.

The aim of the present study was to evaluate the effects of low-level laser therapy (LLLT) and biphasic alloplastic bone graft material on diabetic bone healing. Induction of diabetes was performed in 14 male Sprague-Dawley rats by intraperitoneal injection of a 50 mg/kg dose of streptozotocin. Two bilaterally symmetrical non-critical-sized bone defects were created in the parietal bones in each rat. Right defects were filled with biphasic alloplastic bone graft. Rats were randomly divided into 2 groups, with 1 group receiving 10 sessions of LLLT (GaAlAs, 78.5 J/cm, 100mW, 0.028 cm beam). The LLLT was started immediately after surgery and once every 3 days during postoperative period. At the end of treatment period, new bone formation and osteoblast density were determined using histomorphometry. Empty (control), graft-filled, LLLT-treated and both graft-filled and LLLT-treated bone defects were compared. New bone formation was higher in the graft treatment samples compared with the control (P = 0.009) and laser samples (P = 0.029). In addition, graft-laser combination treatment samples revealed higher bone formation than control (P = 0.008) and laser (P = 0.026) samples. Osteoblast density was significantly higher in the laser treatment (P <0.001), graft treatment (P = 0.001) and graft-laser combination treatment (P <0.001) samples than control samples. In addition, significantly higher osteoblast density was observed in the graft-laser combination treatment samples compared to the graft treatment samples (P = 0.005). The LLLT was effective to stimulate osteoblastogenesis but failed to increase bone formation. Graft augmentation for treatment of bone defects seems essential for proper bone healing in diabetes, regeneration may be supported by the LLLT to enhance osteoblastogenesis.

Odontogenic effects of two calcium silicate-based biomaterials in human dental pulp cells.

BACKGROUND: The goal of treating exposed pulp with an appropriate pulp capping material is to promote the dentinogenic potential of the pulpal cells. There have been recent attempts to develop more effective pulp-capping materials. OBJECTIVES: The aim of this study was to evaluate the effect of newly developed calcium silicate-based material on odontogenic differentiation of primary human dental pulp cells (HDPCs), in comparison with a contemporary calcium silicate-based material. MATERIAL AND METHODS: Human dental pulp cells isolated from dental pulps were cultured in standard culture conditions in Dulbecco's Modified Eagle's Medium (DMEM) and then the effects of Micro-Mega mineral trioxide aggregate (MM-MTA) (Micro-Mega, Besançon, France) and ProRoot MTA (MTA) (Dentsply Sirona, Tulsa, USA) (positive control) were evaluated on HDPCs at 1, 7 and 14 days. Untreated cells were used as a negative control. Odontoblastic differentiation was assessed by alkaline phosphatase (ALP) activity. Runtrelated transcription factor 2 (RUNX2), alkaline phosphatase liver/bone/kidney (ALPL), bone morphogenetic protein 2 (BMP2), dentin sialophosphoprotein (DSPP), and Distal-less homeobox 3 (DLX3), as odontoblastic/ osteoblastic expression markers, were evaluated by semi-quantitative real-time polymerase chain reaction (RT-PCR) analysis. Calcium levels of culture media were also determined. RESULTS: The MM-MTA group significantly increased the expression of BMP2 compared with that of the MTA group at 3 different time periods (p < 0.05). The up-regulation of ALPL between day 1 and 14 and the up-regulation of DSPP between day 7 and 14 were significant in both groups (p < 0.05). Micro-Mega MTA and MTA exhibited similar messenger RNA (mRNA) expression levels of ALPL, DSPP, RUNX2, DLX3, and ALP activities, as well as calcium levels. CONCLUSIONS: Based on the cell responses observed in this study, MM-MTA might be used efficiently in dental pulp therapy as a potential alternative to MTA.

Effects of Hyaluronic Acid and Hydroxyapatite/Beta-tricalcium Phosphate in Combination on Bone Regeneration of a Critical-size Defect in an Experimental Model.

Hyaluronic acid (HyA) is an outstanding new product in the field of oral and maxillofacial surgery. The aim of this study was to evaluate the effects of HyA on bone regeneration in critical-size calvarial defects. Twenty-four female Sprague-Dawley rats were used in the present study. In each rat, 4 critical-size defects received different treatments: no treatment (control); HyA; Graft; and HyA + Graft combination. New bone formation, defect closure, inflammation, vascular proliferation, immature bone formation, mature bone formation, and bone marrow existence were investigated based on histological findings. The healing parameters related to bone formation (new bone formation, defect closure, immature bone formation) were significantly higher in the HyA group compared with the control group. However, HyA alone was unable to induce sufficient bone regeneration compared with treatments involving graft materials (Graft and HyA + Graft). In the Graft and HyA + Graft groups, prominent enhancement of all healing parameters was noted. The present results demonstrate that HyA alone did not adequately enhance bone regeneration in critical-size defects. Moreover, addition of HyA to a biphasic alloplastic graft material did not result in improved regeneration compared with the graft material alone.

Mechanical evaluation of six techniques for stable fixation of the sagittal split osteotomy after counterclockwise mandibular advancement.

We have evaluated the resistance to displacement of six stable methods of fixation of a sagittal split ramus osteotomy (SSRO) in the mandibular advancement with counterclockwise rotation. We tested 60 synthetic hemimandibles in six groups of 10 each: Group I - fixation with a straight four-hole 2.0mm miniplate; Group II - a straight six-hole 2.0mm miniplate; Group III - two straight 2.0mm four-hole miniplates; Group IV - an eight-hole 2.0mm (grid plate); Group V - a 2.0mm four-hole straight miniplate and 2.0×12mm bicortical screw; and Group VI - a straight four-hole 2.0mm locking miniplate. We applied a linear force in the region between the canine and the first premolar using a universal testing machine (EMIC- DL2000) with a loading cell of 10 KN. The loads at 1, 3, and 5mm displacement were recorded (N) and the data transmitted from the load cell to a computer. Results were analysed using analysis of variance (ANOVA) (p<0.001) and the Tukey post-test for comparison of the significance of the differences between the groups. For the three degrees of displacement, fixation with two straight 2.0mm plates and with the grid plate gave higher load values.

Stress Distribution on Short Implants at Maxillary Posterior Alveolar Bone Model With Different Bone-to-Implant Contact Ratio: Finite Element Analysis.

The aim of this study was to evaluate the stress distribution of the short dental implants and bone-to-implant contact ratios in the posterior maxilla using 3-dimensional (3D) finite element models. Two different 3D maxillary posterior bone segments were modeled. Group 1 was composed of a bone segment consisting of cortical bone and type IV cancellous bone with 100% bone-to-implant contact. Group 2 was composed of a bone segment consisting of cortical bone and type IV cancellous bone including spherical bone design and homogenous tubular hollow spaced structures with 30% spherical porosities and 70% bone-to-implant contact ratio. Four-millimeter-diameter and 5-mm-height dental implants were assumed to be osseointegrated and placed at the center of the segments. Lateral occlusal bite force (300 N) was applied at a 25° inclination to the implants long axis. The maximum von Mises stresses in cortical and cancellous bones and implant-abutment complex were calculated. The von Mises stress values on the implants and the cancellous bone around the implants of the 70% bone-to-implant contact group were almost 3 times higher compared with the values of the 100% bone-to-implant contact group. For clinical reality, use of the 70% model for finite element analysis simulation of the posterior maxilla region better represents real alveolar bone and the increased stress and strain distributions evaluated on the cortical and cancellous bone around the dental implants.

Incidence of root canal treatment of second molars following adjacent impacted third molar extraction.

BACKGROUND/PURPOSE: The aim of this study was to evaluate the incidence of requirement for root canal treatment of adjacent second molars following the surgical extraction of an impacted third molar. MATERIALS AND METHODS: The dental records of 6323 consecutive patients who had impacted third molars removed surgically were evaluated and the incidence of postoperative root canal treatment requirement of adjacent second molars was determined. Patients who required root canal treatment of neighboring second molars were accepted as the study group, while the remaining patients were accepted as a control group. Sex, age at the time of the operation, localization of third molar, the depth of impaction, angulation of the tooth, and the professional experience of the surgeon performing the operation were evaluated from patient records. RESULTS: The incidence of requirement of root canal treatment for second molars following a neighboring impacted third molar extraction was 0.17% (11/6323) and invariably occurred in the mandible. The mean age of the study group was found to be significantly higher than the control group (31 years vs. 23 years). The years of professional experience of the surgeons was significantly lower in the study group than in the control group. CONCLUSION: Although the incidence is minimal, iatrogenic subluxation injuries occurring during the surgical removal of impacted third molars can lead to pulpal complications and a requirement for root canal treatment of adjacent second molars.

Radiological and Histological Evaluation of the Effects of Cortical Perforations on Bone Healing in Mandibular Onlay Graft Procedures.

BACKGROUND: Perforations of the cortical bone may be an advantage for the success of the autogenous bone graft procedure, but whether this perforation has a positive effect on the bone remains controversial. PURPOSE: This study evaluates the effects of cortical perforation of the autogenous bone block graft radiologically and histologically. MATERIALS AND METHODS: Seven adult pigs were used for this study. On the experimental side, cortical perforation at the host site was prepared, while no perforation was done on the control side. The specimens were evaluated, and the Wilcoxon signed-rank test was used for statistical analysis. RESULTS: In the radiological evaluation, the Wilcoxon signed-rank test indicated no significant differences in densities among the grafts (p = .23) with a mean of 4.29 ± 0.951 for the unperforated graft side and 3.57 ± 0.976 for the decorticated graft side. In histological evaluation, there was a significant difference in the thickness of the grafts between the groups (experimental group 3.71 ± 1.286, control group: 4.71 ± 0.488; p = .033). However, when the remodeling and osteoblastic activity in the grafts were measured, no significant differences were observed between the groups (p = 1 and p = .133, respectively). CONCLUSION: In augmentation with mandibular onlay bone grafts, cortical perforations in the recipient site make no distinct contribution to bone healing within 12 weeks.

Repositioning a prosthetically unfavorable implant by vertical distraction osteogenesis.

Prosthetically unfavorable implant positions challenge patients and restorative dentists. Surgical correction of malpositioned implants may be an alternative technique for esthetically and biomechanically acceptable prosthetic restorations. This case report describes an alveolar distraction technique used to coronally reposition a dental implant and the 3-year results in the maintenance phase. To our knowledge, long-term follow-up of this method of correction is unprecedented. The present case report describes the repositioning of an apically positioned and fully osseointegrated implant at the right maxillary canine region using an alveolar distraction technique. Distraction was performed at 1 mm per day and ended when the implant moved 6 mm coronally. After a consolidation phase of 8 weeks, an implant-supported fixed prosthetic restoration was performed. Healing was uneventful after removal of the distractor. During the 3-year follow-up, the implant was fully functional with minimal probing depths, negligible signs of inflammation, and no further bone loss. This intervention illustrates the promise of an alveolar distraction osteogenesis procedure for vertical repositioning of apically positioned implants. This technique also provided soft and hard tissue remodeling to obtain an esthetic and stable restoration.

Comparison of stability of 2.0 mm standard and 2.0 mm locking miniplate/screws for the fixation of sagittal split ramus osteotomy on sheep mandibles.

Ten unembalmed adult sheep mandibles were used. The mandibles were sectioned in the midline, followed by sagittal split ramus osteotomies to obtain 20 hemimandibles. Each distal segment was advanced 5mm on each hemimandible. Ten of the specimens were fixed with 4-hole extended 2.0 mm titanium miniplates and screws and the other 10 were fixed with 4-hole extended 2.0 mm locking miniplates/screws. Each fixed specimen was mounted on a servo-hydraulic testing unit with the fixation device, and was tested to a range of forces of 0-140 N. The displacement values (mm) under 20, 60, 120, and 140 N were compared with the help of the Mann-Whitney U-test, and there were no significant differences between them at any force tested. Locking miniplate/screws and standard miniplate/screws showed similar displacement values at the range of forces tested.

Stability of locking and conventional 2.0-mm miniplate/screw systems after sagittal split ramus osteotomy: finite element analysis.

OBJECTIVE: The aim of this study was to evaluate the mechanical stresses over the bone and hardware after sagittal split ramus osteotomy (SSRO) fixed with standard titanium or locking plate/screws using finite element analysis. STUDY DESIGN: A 3-dimensional finite element model of the mandible was created, and SSRO and 5 mm advancement was simulated on a computer model. The model was fixed with either 2.0-mm titanium conventional miniplate/screw or 2.0-mm titanium locking miniplate/screw system, and oblique 200 N bite force was applied. RESULTS: The values of von Mises stresses in the cortical layer of the distal segment using the locking plate system was higher. However, in the cortical layer of the proximal segment the stresses were higher at conventional plate system. In the spongiosa layers of both segments, stresses were higher with the conventional plate system. CONCLUSION: The locking miniplate/screw system spreads the load over the plate and screws and diminishes the amount of force transfered to each unit.

Comparison of intraosseous and extraosseous alveolar distraction osteogenesis.

PURPOSE: To evaluate and compare intraosseous and extraosseous alveolar distraction osteogenesis. PATIENTS AND METHODS: Twenty-three distractors (13 intraosseous; 10 extraosseous) were placed in 21 patients (9 males, 12 females; age range, 12 to 55 years; mean age, 37.9 years) with alveolar ridge deficiencies. Periodontal disease and alveolar resorption following tooth removal was the most common reason for alveolar distraction osteogenesis (n = 14). The length of the segments were less than 2 cm in 15 defects, 2 to 4 cm in 2 defects and more than 4 cm in 6 defects. At the end of consolidation period 25 implants were inserted to the intraosseous group and 17 implants to the extraosseous group. RESULTS: In 21 patients with 23 distracted sites, the mean alveolar distraction was 11.6 mm (range, 5 to 20 mm). The overall complication rates in the intraosseous and extraosseous groups were 61.5% and 50%, respectively. Complications of both groups were mostly minor (95.8%; tilting of the segment, rod interference), only 1 segment fracture in the intraosseous group (4.2%) was considered as a major complication. The most common minor complication in the intraosseous group was tilting of the distracted segment (38.3%). Rod interference with the opposing arch (30%) was the most common minor complication in the extraosseous group. The survival rates of the implants for intraosseous and extraosseous groups were 88% and 94%, respectively. Although complication rate was higher and implant success rate was lower in the intraosseous group, there was no statistical significance between the groups (P > .05). CONCLUSION: Intraosseous and extraosseous alveolar distractors presented no statistically significant complication rates and implant success rates. The clinician must choose an ideal size and type of the distractor according to the defect size, shape, patient tolerance, and distance to the opposing arch.

Reconstruction of a total maxillectomy defect with a zygomatic implant-retained obturator.

Treatment options of maxillary fibrous dysplasia are surgical recontouring or total or partial maxillectomy depending on the site and behavior of the lesion. Among the reconstruction procedures, which include many surgical options, reconstruction using a maxillary obturator is the least invasive one. This report describes a case of aggressive maxillary fibrous dysplasia that was treated with a total maxillectomy and reconstructed with a malar implant-retained maxillary obturator.