Do metal artifact reduction algorithms influence the detection of implant-related injuries to the inferior alveolar canal in CBCT images?

BACKGROUND: The routine application of dental implants for replacing missing teeth has revolutionized restorative and prosthetic dentistry. However, cone beam computed tomography (CBCT) evaluations of structures adjacent to the implants are limited by metal artifacts. There are several methods for reducing metal artifacts, but this remains a challenging task. This study aimed to examine the effectiveness of metal artifact reduction (MAR) algorithms in identifying injuries of implants to the inferior alveolar canal in CBCT images. METHOD: In this in vitro study, mono-cortical bone windows were created and the inferior alveolar canal was revealed. Using 36 implants, pilot drill and penetration damage of the implant tip into the canal was simulated and compared to the control implants with distance from the canal. CBCT images were evaluated by four experienced observers with and without the MAR algorithm and compared to direct vision as the gold standard. The values of accuracy, sensitivity, and specificity were obtained and compared by receiver operating characteristic (ROC) curve (α = 0.05). RESULT: The area under the ROC curve values for detection of pilot drill injuries varied between 0.840-0.917 and 0.639-0.854 in the active and inactive MAR conditions, respectively. The increase in ROC area was only significant for one of the observers (P = 0.010). For diagnosing penetrative injuries, the area under the ROC curve values was between 0.990-1.000 and 0.722-1.000 in the active and inactive MAR conditions, respectively. The improvement of ROC curve values in active MAR mode was only significant for one of the observers (P = 0.006). CONCLUSION: Activation of MAR improved the diagnostic values of CBCT images in detecting both types of implant-related injuries to the inferior alveolar canal. However, for most observers, this increase was not statistically significant.

Granular cell odontogenic tumor: report of a rare case and a review of literature.

BACKGROUND: Granular cell odontogenic tumor (GCOT) is a rare neoplasm with about 45 cases reported in the literature. It usually occurs in the posterior mandible of middle-aged women. CASE PRESENTATION: We report a case of asymptomatic GCOT in the posterior mandible of a 28 years old female and provide a literature review of GCOT cases. Some unusual features such as root resorption, displacement of inferior tooth canal, and multilocular appearance were considerable in this case. CONCLUSIONS: Complete surgical excision of the lesion was beneficial for the patient.

Histological and Radiological Evaluation of Low-Intensity Pulsed Ultrasound Versus Whole Body Vibration on Healing of Mandibular Bone Defects in Rats.

Background and Objectives: Mechanical stimulation can improve the structural properties of the fracture site and induce the differentiation of different cell types for bone regeneration. This study aimed to compare the effect of low-intensity pulsed ultrasound stimulation (LIPUS) versus whole body vibration (WBV) on healing of mandibular bone defects. Materials and Methods: A mandibular defect was created in 66 rats. The rats were randomly divided into two groups of rats. Each group was subdivided randomly by three groups (n = 11) as follows: (I) control group, (II) treatment with LIPUS, and (III) treatment with WBV. The radiographic changes in bone density, the ratio of lamellar bone to the entire bone volume, the ratio of the newly formed bone to the connective tissue and inflammation grade were evaluated after 1 and 2 months. Results: LIPUS significantly increased the radiographic bone density change compared to the control group at the first and second month postoperatively (p < 0.01). WBV only significantly increased the bone density compared to the control group at the second month after the surgery (p < 0.01). Conclusions: Application of LIPUS and WBV may enhance the regeneration of mandibular bone defects in rats. Although LIPUS and WBV are effective in mandibular bone healing, the effects of LIPUS are faster and greater than WBV.

Continuous distraction osteogenesis device with MAAC controller for mandibular reconstruction applications.

BACKGROUND: Distraction osteogenesis (DO) is a novel technique widely used in human body reconstruction. DO has got a significant role in maxillofacial reconstruction applications (MRA); through this method, bone defects and skeletal deformities in various cranio-maxillofacial areas could be reconstructed with superior results in comparison to conventional methods. Recent studies revealed in a DO solution, using an automatic continuous distractor could significantly improve the results while decreasing the existing issues. This study is aimed at designing and developing a novel automatic continuous distraction osteogenesis (ACDO) device to be used in the MRA. METHODS: The design is comprised of a lead screw translation mechanism and a stepper motor, placed outside of the mouth to generate the desired continuous linear force. This externally generated and controlled distraction force (DF) is transferred into the moving bone segment via a flexible miniature transition system. The system is also equipped with an extra-oral ACDO controller, to generate an accurate, reliable, and stable continuous DF. RESULTS: Simulation and experimental results have justified the controller outputs and the desired accuracy of the device. Experiments have been conducted on a sheep jaw bone and results have showed that the developed device could offer a continuous DF of 38 N with distraction accuracy of 7.6 nm on the bone segment, while reducing the distraction time span. CONCLUSION: Continuous DF with high resolution positioning control, along with the smaller size of the distractor placed in the oral cavity will help in improving the result of the reconstruction operation and leading to a successful DO procedure in a shorter time period. The developed ACDO device has less than 1% positioning error while generating sufficient DF. These features make this device a suitable distractor for an enhanced DO treatment in MRA.

Chin Symphysis Bone, Allograft, and Platelet-Rich Fibrin: Is the Combination Effective in Repair of Alveolar Cleft?

PURPOSE: Secondary grafting of alveolar defects with iliac crest bone is a common treatment method in cleft patients. The aim of this study was to evaluate the effectiveness of the combination of symphysis bone, allograft, and platelet-rich fibrin in regeneration of alveolar defects compared with iliac bone graft. MATERIALS AND METHODS: In this randomized clinical trial, patients with unilateral alveolar defects were divided randomly into two categories. Group A comprised patients in whom the combination of chin symphysis bone plus allogeneic bone material plus leukocyte- and platelet-rich fibrin was considered for treatment. Group B comprised patients in whom iliac bone graft was considered. Cone beam computed tomography before treatment and 1 year postoperatively was used for measurement of bone formation (bone volume in cubic centimeters). The data were analyzed by paired t and χ2 tests via SPSS software (version 23; IBM, Armonk, NY). P < .05 was considered significant. RESULTS: Each group included 10 patients (with 6 male patients in group A and 5 male patients in group B). The mean age of patients in groups A and B was 9.5 ± 1.5 years and 9.9 ± 1.9 years, respectively. The mean volume of alveolar defects was 0.89 ± 0.29 cm3 in group A and 0.95 ± 0.27 cm3 in group B. The percentage of bone regeneration in groups A and B was 69.5% and 73.8%, respectively. CONCLUSIONS: It seems that chin symphysis bone plus allogeneic bone material plus platelet-rich fibrin is a proper combination for bone regeneration in alveolar defects with a small to moderate volume range.

Reconstruction of Severely Atrophied Mandible and Simultaneous Implant Insertion with an Inverted Sandwich Technique.

Objectives: To reconstruct and rehabilitate a severely atrophied mandible. Case presentation. A 40-year-old female patient with the chief complaint of denture instability was admitted to our care. In our opinion, the optimum reconstructive method for their severely atrophied mandible (width of 4 mm) was bone grafting with an inverted sandwich technique. 2 split-thickness autogenous calvarial grafts were attained. 4 onlay bone blocks were prepared, placed with an inverted sandwich technique, and fixed with 8 lag screws. 4 implants (Osstem, ⌀4×10 mm) were placed simultaneously, and an immediate post-operation cone beam computed tomography confirmed the proper placement of the grafts and implants. No complications were reported within 4 and 8 months following graft and implant placement. Final impressions for full dental rehabilitation were taken at the 8-month follow-up. Conclusion: Split-thickness calvarial grafts and simultaneous implant placement seem to be a very efficient and promising approach for major reconstruction of the mandible. However, further studies are recommended.

Histopathological assessment of the preventive effect of leukocyte-platelet-rich fibrin on bisphosphonate-related osteonecrosis of the jaw following dental extraction: An animal study.

Background: Leukocyte- and platelet-rich fibrin (L-PRF) could be considered a preventive measure in Bisphosphonate-Related Osteonecrosis of the Jaw (BRONJ). The present experiment aimed to assess the preventive effects of L-PRF on osteonecrosis of the jaw in rats. Methods: In this interventional animal study with a split-mouth design, 28 rats were randomly allocated to saline (negative control), bisphosphonate (positive control), and Bis + L-PRF (case) groups. Bilateral extraction of maxillary molar teeth was performed followed by random application of L-PRF to one of the extraction sockets treated with Zoledronic acid for four weeks. Clinical occurrence of BRONJ and histopathologic evaluations were done, and data were subjected to the Kruskal-Wallis test, Mann-Whitney U test and exact Fisher test performed using SPSS 25. The significance level was set at 0.05. Results: The application of L-PRF resulted in a 41.67% reduction in osteonecrosis centers and the number of osteoclast cells. Also, Kruskal Wallis test results showed a significant difference among the three groups regarding the frequency distribution of inflammation severity. However, no significant difference was detected regarding the frequency distribution of the blood vessels (Kruskal Wallis test, P-value = 0.649). Conclusion: It could be inferred that possible preventive effects on the clinical occurrence of osteonecrosis could be expected from the application of L-PRF.

Evaluation of the effect of green tea extract on postoperative pain management following surgical removal of impacted mandibular third molar.

Background: Pain following surgical removal of impacted molars has remained a principal concern among practitioners. Since green tea has anti-inflammatory and anti-bacterial properties, the current study aimed to evaluate the efficacy of green tea extract local application in controlling postoperative pain following surgical extraction of the impacted mandibular third molar teeth. Materials and Methods: In a double-blinded randomized controlled trial study with a split-mouth design, 32 patients underwent bilateral removal of impacted third molars in a 2-month time interval; afterward, the sterile gauzes impregnated with green tea extract and saline were applied randomly to the surgical sites. Postoperative pain was evaluated 6, 12, 24, and 48 h after surgery using a questionnaire based on the Visual Analog Scale (VAS) and the number of analgesics used after surgery. Data were subjected to exact and Chi-square tests with the significance level set at 0.05. Results: There was a decrease in the mean scores of the VAS and the mean number of analgesic consumptions in the first 2 days after surgery. Chi-square test results showed a significant reduction in the VAS scores after applying the green tea extract only 6 and 12 h after surgery (P < 0.05). Moreover, the number of analgesic consumptions was significantly lower in the green tea group compared to the control group. Conclusion: Green tea extract may be an appropriate and safe choice for postoperative pain control after surgical extraction of the impacted mandibular third molar teeth.

Effect of Dexmedetomidine Added to Lidocaine Cartridge on the Level of Patient Sedation, Cooperation, and Patient and Surgeon Satisfaction during Mandibular Third-Molar Extraction Surgery: A Randomized Double-Blind Controlled Trial.

Background: Various methods have been introduced for anxiety control during third-molar extraction surgery. Dexmedetomidine (DEX) is known to have analgesic, anxiolytic, and sympatholytic properties with minimal adverse effects. This study aimed to evaluate the impact of the local injection of the combination of DEX and Lidocaine on patients' anxiety and the surgeon's satisfaction during third-molar extraction surgery. Methods: A total number of 26 healthy volunteers with symmetrical bilateral impacted mandibular third-molar teeth indicated for surgical removal were included in this double-blind randomized controlled trial. A single experienced surgeon performed two surgical extraction procedures within at least four-week time intervals using anesthetic cartridges containing "DEX + LIDO" or "LIDO alone" used randomly on each side for each patient. The Visual Analog Scale and the SDFQ index were used to evaluate patients' anxiety and surgeon satisfaction during the procedure. Results: SDFQ reports showed that patients in the "DEX" group were 1.5 times more relaxed than those in the "LIDO alone" group. As a result, the level of sedation was considered statistically significant between the two groups (Wilcoxon test, P value <0.019). Wilcoxon test results also showed significant differences between the two groups regarding patients' overall cooperation in terms of interfering movement and verbal presentation of discomfort (P value <0.05); however, this difference was not considered significant regarding nonverbal signs of discomfort (P value >0.05). Moreover, both the surgeon and the patients reported a significantly higher satisfaction rate in the DEX group (paired T-test, df = 25, P value <0.05). Conclusions: It was inferred from the outcomes of the present study that the application of DEX added to the LIDO local anesthesia cartridge could significantly benefit anxious patients with previous unpleasant dental treatment experiences. Trial Registration. This trial is registered with the clinical trial registration number: IRCT20200406046966N.

Functional denture obturator for marsupialization of residual cyst: A novel approach.

In this report, we have introduced a novel technique for marsupialization treatment in a 50-year-old edentulous female patient with residual cysts in the mandibular bone. The clinical symptoms and para-clinical founding in addition to the surgical procedure and post-operative outcome have been discussed.

Two-Axis Continuous Distractor for Mandibular Reconstruction.

The application of Distraction Osteogenesis (DO) techniques in the reconstruction of skeletal deficiencies is a relatively new topic in the fields of oral and maxillofacial surgeries. In many reconstruction applications, using DO is the preferred technique, as opposed to conventional reconstruction techniques, as there are more advantages and fewer side effects when it is used. The first generation of DO devices is made up of manual distractors that can apply an intermittent distraction force to the bone segment during the distraction process. Manual DO techniques have shown the functionality of the DO technique. Further research has recently been performed on the development of automatic devices for generating a controlled continuous force. However, the existing automatic techniques have limitations, and are yet to be used in reconstruction applications in humans. There is still a gap between the developed techniques and an ideal distractor to be used in mandibular reconstruction surgeries. In this research, a two-axis continuous distractor is proposed for use in mandibular reconstruction applications. The proposed distractor can generate two continuous distraction forces that can be applied to two independent distraction vectors. The proposed device can perform the standard distraction process using the predetermined distraction factors. The control system has a high positioning accuracy and resolution in controlling the position of the intra-oral end effectors while applying two continuous forces for moving the bone segment. The proposed two-axis continuous distractor meets the current requirements, and can be used as an ideal continuous DO device for different mandibular reconstruction applications.

Hybrid Distractor for Continuous Mandibular Distraction Osteogenesis.

Distraction osteogenesis (DO) is a reconstruction method for repairing bone deficiencies in the oral and maxillofacial area. Manual DO techniques have shown the functionality of the DO method for bone tissue reconstruction. The DO method can improve treatment conditions, as well as the quality of the reconstructed bone, compared with conventional techniques. Recently, continuous DO devices have been proposed to enable an automatic DO process while using a continuous force for moving the bone segment (BS). Animal studies and clinical trials have shown the successful application of continuous distractors in terms of improving DO factors, including rate and rhythm. The continuous DO technique can shorten the treatment time and enhance the quality of the regenerated tissue. However, the developed continuous distractors are yet to be used in human applications. In this study, by combining motor-driven and hydraulic techniques, a hybrid distractor is proposed. The hybrid distractor is capable of generating a continuous distraction force while controlling the position of the BS in a linear vector, with a high positioning accuracy. Results of modelling and experimental study revealed that the proposed hybrid distractor met all required factors for enabling a continuous DO procedure in humans. The proposed distractor is capable of eliminating the drawbacks of exiting techniques in terms of generating and transferring a controlled distraction force to the BS. The wireless control, as well as the small size of the device, makes this device a suitable solution for use in the reconstruction of bone defects in the maxillofacial area in humans.

Evaluation of the CBCT imaging accuracy in the volumetric assessment of unilateral alveolar cleft.

INTRODUCTION: Appropriate radiographic evaluation is a fundamental step for determining the topography of the defect before the surgical intervention for alveolar bone grafting. Evaluation of cleft volume by CBCT has been done in dry skull samples in previous studies and it was recommended as an effective tool in the volumetric evaluation of the bone defect prior to the surgery. The purpose of this study was to evaluate the accuracy of preoperative clinical use of CBCT2 imaging in determining the alveolar cleft volume. MATERIAL AND METHODS: We performed a clinical study. 20 patients with unilateral alveolar cleft underwent preoperative radiographic evaluation using CBCT scan. Volumetric measurement was performed by an oral and maxillofacial radiologist using 0.5, 1, and 2 mm slices and an oral and maxillofacial surgeon using 2 mm slices. After the closure of the nasal floor and palatal mucosa, the alveolar defect was clinically measured with putty impression material. Descriptive and bivariate statistics were computed and the p-value was set at 0.05. RESULTS: This study showed that there is a statistically significant difference between CBCT-estimated and clinical volumes of the alveolar cleft (paired T-test, p-value < 0.05). CONCLUSION: Considering the significant difference between clinical and CBCT-estimated volumes of the alveolar cleft, CBCT imaging is not considered an accurate tool for pre-operative volumetric assessment of the alveolar cleft.

Injection of Lidocaine Alone versus Lidocaine plus Dexmedetomidine in Impacted Third Molar Extraction Surgery, a Double-Blind Randomized Control Trial for Postoperative Pain Evaluation.

Objectives: Administration of medications such as dexmedetomidine as a topical anesthetic has been suggested in the pain control in dentistry. This double-blind randomized control trial study evaluated postoperative pain and associated factors following impacted third molar extraction surgery. Lidocaine alone was taken as the control and lidocaine plus dexmedetomidine as the intervention. Materials and Methods: Forty patients undergoing mandibular third molar extraction entered the study and were randomly allocated to the control and interventional groups. 0.15 ml of dexmedetomidine was added to each lidocaine cartridge and the drug concentration was adjusted to 15 µg for the intervention group while only lidocaine was used in the control group. A visual analog scale was used to measure and record pain levels at the end of the surgery and 6, 12, and 24 hours after the surgery and number of painkillers taken by the patients after the surgery was also recorded. Results: Pain scores of the intervention group decreased significantly during the surgery and also 6, 12, and 24 hours after the surgery compared to the control group. The pain score was correlated significantly with our intervention during the surgery and also 6 and 12 hours after that (all P value < 0.05). There was a nonsignificant reduction in the number of painkillers taken by the patients at 6, 12, and 24 hours after surgery (all P value > 0.05). Conclusion: In patients undergoing molar surgery, administration of a combination of dexmedetomidine and lidocaine is beneficial for the pain control. Clinical Relevance. Compared to the injection of lidocaine alone, combination of dexmedetomidine and lidocaine can be used for a better pain control in molar surgeries.

Review of physical stimulation techniques for assisting distraction osteogenesis in maxillofacial reconstruction applications.

Distraction Osteogenesis (DO) is an emerging limb lengthening method for the reconstruction of the hard tissue and the surrounding soft tissue, in different human body zones. DO plays an important role in treating bone defects in Maxillofacial Reconstruction Applications (MRA) due to reduced side effects and better formed bone tissue compared to conventional reconstruction methods i.e. autologous bone graft, and alloplast implantation. Recently, varying techniques have been evaluated to enhance the characteristics of the newly formed tissues and process parameters. Promising results have been shown in assisting DO treatments while benefiting bone formation mechanisms by using physical stimulation techniques, including photonic, electromagnetic, electrical, and mechanical stimulation technique. Using assisted DO techniques has provided superior results in the outcome of the DO procedure compared to a standard DO procedure. However, DO methods, as well as assisting technologies applied during the DO procedure, are still emerging. Studies and experiments on developed solutions related to this field have been limited to animal and clinical trials. In this review paper, recent advances in physical stimulation techniques and their effects on the outcome of the DO treatment in MRA are surveyed. By studying the effects of using assisting techniques during the DO treatment, enabling an ideal assisted DO technique in MRA can be possible. Although mentioned techniques have shown constructive effects during the DO procedure, there is still a need for more research and investigation to be done to fully understand the effects of assisting techniques and advanced technologies for use in an ultimate DO procedure in MRA.