Patient-specific virtual simulation in the clinical training for prosthetic dentistry.

INTRODUCTION: Dental education always involves live patient treatment, and clinical training for each patient is different for students. Using an intraoral scanner and Simodont Dental Trainer, we can provide students with an opportunity to train on actual patient cases in a virtual environment before real preparation. This study aimed to develop, implement and test patient-specific virtual simulation training in prosthetic dentistry curriculum. MATERIALS AND METHODS: Before the actual preparation, the students' patients were scanned using 3Shape intraoral scanner. Thereafter, the .stl file was uploaded to Simodont Dental Trainer (Nissin dental products) where all the scanned teeth were prepared virtually. The 'prepared' .stl file was downloaded and submitted to the teacher. Instruction manuals for virtual simulation patient-specific tasks were provided. The students were asked to voluntarily complete the survey, at the end of the course. RESULTS: Forty-two 4th year students from the Faculty of Dentistry performed a patient-specific virtual simulation training task and completed a survey. The created training materials served as guidelines for students to perform all the steps on their own without teacher assistance, except in the final step, where the teacher evaluated the digital preparation. Students appreciated the amount of information provided regarding the technologies used and patient-specific tasks. Students admitted that the patient-specific task was more interesting than standard tasks. However, they were not satisfied with the technical performance of Simodont Dental Trainer or the reflection of reality. CONCLUSION: Patient-specific virtual simulation can be accepted by students for training before actual teeth preparation in the clinic. However, technical improvements are required in this regard.

The Effect of General Bone Mineral Density on the Quantity and Quality of the Edentulous Mandible: A Cross-Sectional Clinical Study.

BACKGROUND: Osteoporosis is a disease which is characterized by a decrease in general bone mineral density (BMD), resulting in decreased bone strength and an increased risk of bone fractures. The effect of reduced BMD on the jawbones is still not fully understood. The purpose of the study was to evaluate the impact of BMD on the quality and quantity of the edentulous mandible. METHODS: The present study included 127 edentulous postmenopausal women who underwent cone beam computed tomography (CBCT) examinations. BMD measurements of the lumbar spine and femoral necks were performed by dual-energy X-ray absorptiometry. In the cross-sectional CBCT images, three different areas of the mandible (lateral incisor, first premolar, and first molar) were selected. The complete mandibular, trabecular, and cortical bone volumes were measured. All measurements were performed on the total mandibular area, and the basal and alveolar parts of the mandible. RESULTS: The volume of the cortical bone was reduced for females with reduced BMD in the lateral incisor and first premolar regions, both in the total mandibular area and in the basal part of the mandible. The trabecular bone volume statistically significantly increased when the BMD decreased in the complete mandibular area and the basal part of the mandible (linear regression). The total bone volume significantly decreased with a decrease in BMD in the basal part of the mandible. CONCLUSIONS: Reduced BMD has a negative effect on the quantity and quality of bone in the basal part of the edentulous mandible.

Gray values of the cervical vertebrae detected by cone beam computed tomography for the identification of osteoporosis and osteopenia in postmenopausal women.

OBJECTIVES: This study aimed to determine whether the gray values (GVs) of the second and third cervical vertebrae in cone beam computed tomography (CBCT) are affected by general bone mineral density (BMD) in postmenopausal women and to evaluate whether CBCT can be used for predicting the risk of osteoporosis. STUDY DESIGN: The present cross-sectional study included 127 edentulous postmenopausal women (average age, 70.4 ± 8.9 years) who underwent CBCT examinations. BMD measurements of the lumbar spine and both femoral necks were performed by dual-energy x-ray absorptiometry. The CBCT images were analyzed with OnDemand3D Dental software. GVs of the axial and sagittal sections of the cervical second and third vertebral bodies were obtained. RESULTS: The GVs of the second and third cervical vertebrae decreased significantly with decreasing BMD. The axial GV of the second cervical vertebra showed the highest sensitivity (80.6%), highest negative predictive value (89.0%), lowest negative likelihood ratio (0.39), and highest area under the curve value (0.68) to predict osteoporosis. CONCLUSIONS: Women with reduced BMD have lower GVs for the second and third cervical vertebrae. Changes in the GV of the second vertebra can potentially be used to determine the risk of osteoporosis in postmenopausal women.

Soft tissue thickness changes after correcting Class III malocclusion with bimaxillar surgery.

UNLABELLED: THE AIM OF THIS STUDY was to evaluate and analyse soft tissue thickness changes after bimaxillary orthognathic surgery. MATERIALS AND METHODS: Eighty three consecutive patients (54 males and 29 females) with Class III malocclusion operated with bimaxillary orthognathic surgery were enrolled in this study. Standardized lateral cephalograms of adequate quality were analysed. RESULTS: The mean upper lip thickness decreased as a result of the surgery and statistically significant differences were recorded (p<0.01). The statistically significant difference in the post surgical tissue thickness of the lower lip also was recorded (p<0.05). Subjects with thick upper lips compared to patients with thin upper lips demonstrated greater (0.7 mm) and statistically significant (p<0.01) increase of vertical nasal projection. Vertical growth pattern had an influence only on B point to lower lip distance, which exhibited greater (2.2 mm; p<0.01) decrease during observation period. CONCLUSION: It was found differences in the soft tissue responses between patients with thick or thin soft tissues after bimaxillary surgery and it should be taken into account while planning operation.

The stability of bilateral sagittal ramus osteotomy and vertical ramus osteotomy after bimaxillary correction of class III malocclusion.

INTRODUCTION: The purpose of this retrospective cephalometric study was to compare the stability of bilateral sagittal split osteotomy (BSSO) with extra-oral vertical ramus osteotomy (VRO) after correction of class III malocclusion by means of bimaxillary orthognathic surgery. METHODS: The sample comprised 51 consecutively treated patients, 38 females and 13 males, with a mean age of 19.1 years. All had a one-piece Le Fort I osteotomy with maxillary advancement and mandibular setback. VRO was performed in 30 cases, and BSSO was performed in 21 cases. Lateral cephalograms were obtained before surgery, within 1 week of surgery and 1 year after surgery. RESULTS: The mean forward movement of the maxilla was 5.6 mm in both groups (p<0.001). The mean horizontal surgical change in the VRO group was 4.4 mm (p<0.001), and in the BSSO group it was 5.4 mm (p<0.001). In the VRO group, the horizontal relapse was 1.2 mm (p<0.001), and in the BSSO group, it was 1.4 mm (p<0.001). CONCLUSION: There was no difference in the stability between the BSSO and VRO groups. The average relapse in the whole sample was 26% of the surgical movement.

Anterior crossbite correction in primary and mixed dentition with removable inclined plane (Bruckl appliance).

Anterior crossbite correction in early mixed dentition is highly recommended as this kind of malocclusion do not diminish with age. Uncorrected anterior crossbite may lead to abnormal wear of the lower incisors, dental compensation of mandibular incisors leading to thinning of labial alveolar plate and/or gingival recession. There are several methods for solving this problem. In this article we would like to describe removable inclined plane. This is a removable simple functional appliance on the lower arch (jaw), which works as inclined plane. One of the advantage of the Bruckl appliance is that it can also be used as retention appliance after active treatment as well as it is possible to add acrylic teeth if necessary. Therefore it can be used as a removable partial denture in lower jaw in case where there is a premature loss of the primary teeth. The use of this appliance is illustrated with three cases.