Comparative Finite Element Analysis of Short Implants with Different Treatment Approaches in the Atrophic Mandible.

PURPOSE: This three-dimensional finite element analysis study aimed to compare the stresses transmitted to short, tilted, and vertical implants used in different configurations and to the surrounding peri-implant bone in the atrophic mandible. MATERIALS AND METHODS: A three-dimensional model of an atrophic mandible was made using customized computer software. Four models including short, tilted, and vertical implants were constructed with and without cantilever extension. Four or six implants in different configurations were placed into the models and mounted with the same fixed prosthesis. An oblique force of 200 N was bilaterally applied to the most distal part of the fixed denture. Von Mises stress values on implants and minimum and maximum principal stress values transmitted to peri-implant bone were analyzed. RESULTS: The highest stress values recorded in the tilted implants (von Mises: 129 MPa), in the peri-implant bone around the tilted implants (minimum principal stress: -40 MPa), and overall stress values were found to be higher in the model including tilted implants with cantilever extensions. Distally placed short implants, with consequent elimination of the cantilevers, resulted in decreased stress values for all of the treatment variabilities of an atrophic mandible. Von Mises stress values were found as 129 MPa in tilted (model I), 48 MPa in short (model II), 47 MPa in short (model III), and 57 MPa in vertical (model IV) at the most distal implant location. Lower compressive stress values were noted in the bone around straight and short implants compared with the tilted implants in all models (model I, tilted: -40 MPa; model II, short: -34 MPa; model III, short: -33 MPa; model IV, vertical: -25 MPa). CONCLUSION: Distally placed short implants contributed to the reduction of stress values of the implants and the surrounding bone. The combination of two short and four straight implants without cantilevers may be a beneficial design in the rehabilitation of posteriorly atrophic mandibles.

A city-wide survey of dental students' opinions on undergraduate oral surgery teaching.

PURPOSE: This study aimed to carry out a city-wide survey to evaluate undergraduate students' opinions on their oral surgery training by measuring their self-confidence. MATERIALS AND METHODS: A cross-sectional survey of 383 3rd year, 412 4th year and 363 5th year undergraduate dental students from six dental schools in Istanbul with a mean age of 22.73 ± 1.55 was conducted towards the end of the academic year. A web link to the questionnaire was sent to the contact person at the participating dental schools. The questionnaires were anonymously evaluated. Descriptive statistics were calculated, and Chi-square tests were performed to examine the data. A P-value of <.05 was considered to be statistically significant. RESULTS: In total, 1158 responses were returned, representing 67% of the overall students in the 2018-2019 academic year. The male respondents were significantly more self-confident than females in the general aspects of surgical skills. More than half of the respondents (53%) felt confident in oral surgery knowledge to undertake independent practice. Although 5th year respondents felt more confident in the general aspect of the questionnaire, their ability of differentiation of odontogenic and non-odontogenic pain was lower than their counterparts. The majority (86%) of the participants disagreed that the only knowledge required for oral surgery was that of tooth and jaw anatomy. CONCLUSION: This survey revealed perceived confidence in tooth and retained root extraction. The male respondents were found to be more self-confident. There is a need for improvement in surgical skills, recognition of malignancies and differentiation of the origin of the pain.

Evaluation of Stress in Tilted Implant Concept With Variable Diameters in the Atrophic Mandible: Three-Dimensional Finite Element Analysis.

The beneficial mechanical properties provided by greater diameter or short implants increases their usage in the tilted implant concept. The aim of the present study is to compare the stress distribution of 4 different treatment models including variable implant numbers and diameters under a static loading protocol in the atrophic mandible using 3-dimensional finite element analysis. Three models included 2 tilted and 2 vertically positioned implants with different diameters, whereas 2 distally placed short implants were added to the fourth model. The von Mises stress as well as the maximum and minimum principal stress values were evaluated after applying 200 N bilateral oblique loads to the first molar teeth with the inclination of 45° to the longitudinal axis. Tilted implants were associated with higher stress values when compared with vertical implants in all models. The lowest stress values were obtained in the fourth model, including short implants. Although all stress values showed slight increases by descending implant diameters, the stress values of the model including implants with 3.3-mm diameter were within physiologic limits. All in all, an increasing number or diameter of implants may have a positive effect on implant survival. In addition, when narrow-diameter implants need to be inserted in the tilted implant concept, combination with short implants may be recommended for long-term success.

Guided Bone Regeneration Using BioGlue As a Barrier Material With and Without Biphasic Calcium Phosphate.

The aim of this study was to investigate the effects of Bioglue as a mechanical barrier with or without biphasic calcium phosphate (BCP) in a rat tibia model. Sixty Sprague Dawley male rats weighing 250 ±â€Š20 g and 10 to 12 weeks of age were studied. Unicortical defects were created on the right tibia of all rats. Subjects were randomly divided into 3 groups. BioGlue group (24 rats); BioGlue alone, Graft group (24 rats); BioGlue + BCP and Control group; unfilled and uncovered (12 rats). Animals were euthanized at 7th, 21st, and 45th days postoperatively for histological and histomorphometric analyses. BioGlue material exhibited no adverse effects until the end of observation period. Bone-healing scores did not differ statistically between Control and BioGlue group, but found to be lower in Graft group on 21st and 45th days, (P < 0.001 and P < 0.01 on the 21st day and P < 0.01 and P < 0.05 on the 45th day, respectively). New bone formation in Graft group was found to be statistically different from Control group on the 7th and 21st days (P < 0.01 and P < 0.05 respectively), whereas no statistical difference was observed between BioGlue and Control group at all times. The present analysis indicates that BioGlue functioned well as a mechanical barrier allowing new bone formation. No additional benefit of combination treatment was detected in this study design and BCP did not offer any advantage for bone regeneration, thus it can serve as only a space maintainer.

Current management concepts for bisphosphonate-related osteonecrosis of the jaw: a review.

Bisphosphonate (BP) drugs are used to preserve bony tissue in patients diagnosed with osteoporosis and metastatic bone disease. However, these drugs are associated with rare but serious complications. The most commonly encountered adverse effect is bisphosphonate-related osteonecrosis of the jaw (BRONJ). Diagnosis and treatment of teeth that are likely to cause infection and the replacement or adjustment of dentures or restorations that could lead to trauma are the key steps that can be taken before the initiation of BP therapy in order to prevent the development of BRONJ. To date, the most efficacious management approach for BRONJ has not been clearly established. This article presents current approaches for the treatment of BRONJ, including conservative drug therapy and surgical therapy, and discusses new treatment modalities.

Bleeding frequency of patients taking ticagrelor, aspirin, clopidogrel, and dual antiplatelet therapy after tooth extraction and minor oral surgery.

BACKGROUND: Perioperative bleeding complications of ticagrelor, a newer oral antiplatelet, has not been studied in dentistry. Studies about bleeding status after oral surgical procedures in patients receiving continued antiplatelet therapy are also limited. We investigated the effects of continuing aspirin, clopidogrel, ticagrelor, or dual antiplatelet therapy on the frequency of bleeding events in patients undergoing tooth extractions or minor oral surgery. METHODS: In this retrospective study, patient demographic characteristics, medical history, type of antiplatelet therapy, dental procedures, and perioperative bleeding associated with tooth extraction or other minor oral surgical procedures were obtained from the dental records of 222 patients. Bleeding was classified as normal, mild, moderate, or severe. RESULTS: One hundred sixty-eight patients (75.7%) had 1 or more teeth extracted, and 54 patients (24.3%) underwent other minor oral surgical procedures. The most common single antiplatelet regimen was aspirin (n = 123; 55.4%), followed by clopidogrel (n = 22; 9.9%) and ticagrelor (n = 17; 7.7%). Sixty patients (27%) received dual antiplatelet therapy. The overall frequency of postoperative bleeding was 4.9% (11 of 222). The frequencies of postoperative bleeding in the aspirin, clopidogrel, ticagrelor, and dual antiplatelet therapy groups were 3.2%, 4.5%, 5.9%, and 8.3%, respectively (P ≥ .5). None of the patients experienced prolonged bleeding. CONCLUSIONS: Patients taking aspirin, clopidogrel, ticagrelor, and dual antiplatelet therapy experienced acceptable rates of controllable postoperative bleeding after tooth extraction or minor oral surgical procedures. PRACTICAL IMPLICATIONS: In accordance with recommendations from published studies and guidelines, antiplatelet medications, including dual antiplatelet therapy, should not be interrupted for tooth extractions or minor oral surgery.

Clinical Evaluation of Zygomatic Implant-Supported Fixed and Removable Prosthesis.

The aim of our study was to present success and complication rates of 32 zygomatic implants (ZI) and compare satisfaction of patients rehabilitated with ZI supported hybrid prosthesis in atrophic jaws and removable prosthesis in maxillary defects. Sixteen patients who have been diagnosed as atrophic maxilla or maxillary defect were treated with ZI supported hybrid or removable prosthesis between 2008 and 2016 years, respectively. Thirty-two of 70 implants were placed in the zygomatic bone. Two prosthetic groups were compared 1 month after prosthesis delivery in terms of general satisfaction, stability, performance, esthetics, phonetics, hygiene level based on visual analog scale. Zygomatic implants success rate was found 93.7% after a mean follow-up of 28 ±â€Š22 months (range 6-96 months). Thirty of 32 ZIs have been functioning with their prosthesis. The rate of biologic complications related to ZIs was found 9.3% and prosthetic complication's rate related to ZI was 3%. Two early failures of ZIs were recorded. Chewing performance (P: 0.003), stability (P: 0.0001), and phonetics (P: 0.003) were found higher in hybrid prosthetic group. On the other hand, there was a statistically significant difference between groups in favor of removable prosthetic group regarding ease of cleaning (P: 0.007). Our study shows high success rate and minimal complications for 32 ZIs. This procedure seems to be an alternative to the bone grafts or sinus lifting techniques in patient of severely resorbed maxilla or to the obturator prosthesis for maxillectomy patients.

Zygoma Implant-Supported Prosthetic Rehabilitation of a Patient After Bilateral Maxillectomy.

Maxillectomy defects may vary from localized to extensive soft and hard tissue loss. In addition to physical and psychologic damages, functional and aesthetic aspects must be restored. This clinical report describes the rehabilitation of a patient with a zygoma implant-supported obturator prosthesis caused by a subtotal bilateral maxillectomy due to a squamous oral cell carcinoma. Prosthetic rehabilitation of this patient was performed after zygoma implant surgery. A maxillary obturator prosthesis supported by 2 osseointegrated zygoma implants was fabricated. Despite limited mouth opening and anatomic deficiencies, the patient's aesthetic and functional demands were fulfilled.