Effect of mineralized dentin matrix on the prognosis of bone defect and retained root after coronectomy.

OBJECTIVE: To investigate the impact of mineralized dentin matrix (MDM) on the prognosis on bone regeneration and migration of retained roots after coronectomy. MATERIALS AND METHODS: Patients were divided into three groups based on the type of bone graft after coronectomy: Group C (n = 20, collagen), Group T (n = 20, tricalcium phosphate (TCP) + collagen), and Group D (n = 20, MDM + collagen). CBCT scans, conducted immediately and 6 months after surgery, were analyzed using digital software. Primary outcomes, including changes in bone defect depth and retained root migration distance, were evaluated 6 months after surgery. RESULTS: After 6 months, both Groups D and T exhibited greater reduction of the bone defect and lesser retained root migration than Group C (p < 0.001). Group D had greater regenerated bone volume in the distal 2 mm (73 mm3 vs. 57 mm3, p = 0.011) and lesser root migration (2.18 mm vs. 2.96 mm, p < 0.001) than Group T. The proportion of completely bone embedded retained roots was also greater in Group D than in Group C (70.0% vs. 42.1%, p = 0.003). CONCLUSIONS: MDM is an appropriate graft material for improving bone defect healing and reducing retained root migration after coronectomy. CLINICAL RELEVANCE: MDM is an autogenous material prepared chairside, which can significantly improve bone healing and reduce the risk of retained root re-eruption. MDM holds promise as a routine bone substitute material after M3M coronectomy.

The impacts of registration-and-fixation device positioning on the performance of implant placement assisted by dynamic computer-aided surgery: A randomized controlled trial.

OBJECTIVES: To assess the efficacy of dynamic computer-aided surgery (dCAS) in replacing a single missing posterior tooth, we compare outcomes when using registration-and-fixation devices positioned anterior or posterior to the surgical site. Registration is performed on either the anterior or opposite posterior teeth. METHODS: Forty individuals needing posterior single-tooth implant placement were randomly assigned to anterior or posterior registration. Nine parameters were analyzed to detect the deviations between planned and actual implant placement, using Mann-Whitney and t-tests for nonnormally and normally distributed data, respectively. RESULTS: The overall average angular deviation for this study was 2.08 ± 1.12°, with the respective average 3D platform and apex deviations of 0.77 ± 0.32 mm and 0.88 ± 0.32 mm. Angular deviation values for individuals in the anterior and posterior registration groups were 1.58°(IQR: 0.98°-2.38°) and 2.25°(IQR: 1.46°-3.43°), respectively (p = .165), with 3D platform deviations of 0.81 ± 0.29 mm and 0.74 ± 0.36 mm (p = .464), as well as 3D apex deviations of 0.89 ± 0.32 mm and 0.88 ± 0.33 mm (p = .986). No significant variations in absolute buccolingual (platform, p = .659; apex, p = .063), apicocoronal (platform, p = .671; apex, p = .649), or mesiodistal (platform, p = .134; apex, p = .355) deviations were observed at either analyzed levels. CONCLUSIONS: Both anterior and posterior registration approaches facilitate accurate dCAS-mediated implant placement for single missing posterior teeth. The device's placement (posterior-to or anterior-to the surgical site) did not affect the clinician's ability to achieve the planned implant location.

Alveolar ridge preservation of two-wall bone defects using mineralized dentin matrix: An experimental pre-clinical study.

OBJECTIVES: To study bone healing of two-wall bone defects after alveolar ridge preservation using mineralized dentin matrix. MATERIALS AND METHODS: After distal roots extraction of second and fourth premolars (P2, P4) on one lateral mandible in 12 beagles, two-wall bone defects (5 × 5 × 5 mm) were surgically created distally to the remaining mesial roots of P2 and P4. A total of 24 sites were randomly allocated to three groups (implant material- time of execution): mineralized dentin matrix (MDM)-3 m (MDM + collagen membrane; 3 months), MDM-6 m (MDM particles + collagen membrane; 6 months), and C-6 m (collagen membrane only; 6 months). Clinical, radiographic, digital, and histological examinations were performed 3 and 6 months after surgery. RESULTS: The bone healing in MDM groups were better compared to Control group (volume of bone regenerated in total: 25.12 mm3 vs. 13.30 mm3, p = .046; trabecular volume/total volume: 58.84% vs. 39.18%, p = .001; new bone formation rate: 44.13% vs. 31.88%, p = .047). Vertically, the radiological bone level of bone defect in MDM-6 m group was higher than that in C-6 m group (vertical height of bone defect: 1.55 mm vs. 2.74 mm, p = .018). Horizontally, no significant differences in buccolingual bone width were found between MDM and C groups at any time or at any level below the alveolar ridge. The percentages of remaining MDM were <1% in both MDM-3 m and MDM-6 m groups. CONCLUSIONS: MDM improved bone healing of two-wall bone defects and might be considered as a socket fill material used following tooth extraction.

Accuracy of computer-assisted dynamic navigation when performing coronectomy of the mandibular third molar: A pilot study.

OBJECTIVES: The study represents a preliminary evaluation of the accuracy of the dynamic navigation system (DNS) in coronectomy of the mandibular third molar (M3M). METHODS: The study included participants with an impacted M3M near the inferior alveolar canal. The coronectomy planes were designed before the surgery using cone-beam computed tomography (CBCT) imaging data and then loaded into the DNS program. Intraoperatively, the navigation system was used to guide the complete removal of the target crown. Postoperative CBCT imaging was used to assess any three-dimensional deviations of the actual postoperative from the planned preoperative section planes for each patient. RESULTS: A total of 12 patients (13 teeth) were included. The root mean square (RMS) deviation of the preoperatively designed plane from the actual postoperative surface was 0.69 ± 0.21 mm, with a maximum of 1.45 ± 0.83/-1.87 ± 0.63 mm deviation. The areas with distance deviations < 1 mm, 1-2 mm, and 2-3 mm were 71.97 ± 5.72 %, 22.96 ± 6.57 %, and 4.52 ± 2.28 %, respectively. Most patients showed extremely high convexity of the surface area located in the mesial region adjacent to the base of the extraction socket. There was no observable evidence of scratching of the buccolingual bone plate at the base of the extraction socket by the handpiece drill. CONCLUSIONS: These results provide preliminary support for the use of DNS-based techniques when extracting M3M using a buccal approach. This would improve the accuracy of coronectomy and reduce the potiential damage to the surrounding tissue. CLINICAL SIGNIFICANCE: DNS is effective for guiding coronectomy.

Analysis of the accuracy of a dynamic navigation system when performing dental implant surgery with transcrestal sinus floor elevation: A pilot study.

Background/purpose: The success of transcrestal sinus floor elevation (TSFE) is primarily reliant upon the experience of the surgeon owing to the limited operative visibility. To evaluate the accuracy associated with the use of a dynamic navigation system when conducting posterior maxilla implant surgery with TSFE. Materials and methods: Twenty-eight implants were placed in 28 patients requiring implantation in the posterior maxilla via a TSFE approach. The drills were used to access the planned position (within 1 mm of the bottom of the maxillary sinus floor) under dynamic navigation system. TSFE was then accomplished using osteotomes and a piezoelectric device. Lastly, the implant was inserted under the dynamic navigation. Three effective deviations between planned and actual implant placement were then measured including angular deviation (AD, degrees), entry point horizontal deviation (EPHD, mm), and apical point horizontal deviation (APHD, mm). Results: The AD, EPHD, and APHD between the planned and actual implant placement were 3.656 ± 1.665°, 1.073 ± 0.686 mm, and 1.086 ± 0.667 mm, respectively. Premolar site AD values were less than those for molar sites (P = 0.004). No significant differences in these outcomes were observed in different surgeons. Obvious sinus perforation was not detected by immediate postoperative cone beam computed tomography imaging. Conclusion: The accuracy associated with using a dynamic navigation system when conducting posterior maxilla implant surgery via a TSFE approach using piezoelectric devices was comparable. This technique thus achieved appropriate interventional precision and safety while decreasing the morbidity associated with the TSFE approach.

Accuracy of different registration areas using active and passive dynamic navigation systems in dental implant surgery: An in vitro study.

OBJECTIVES: To gauge the relative accuracy of the use of passive and active dynamic navigation systems when placing dental implants, and to determine how registration areas affect the performance of these systems. MATERIALS AND METHODS: Eighty implants were assigned to be placed into 40 total resin mandible models missing either the left or right first molars using either passive or active dynamic navigation system approaches. U-shaped tube registration devices were fixed in the edentulous site for 20 models each on the left or right side. Planned and actual implant positions were superimposed to assess procedural accuracy, and parameters including 3D entry deviation, angular deviation, and 3D apex deviation were evaluated with Mann-Whitney U tests and Wilcoxon signed-rank tests. RESULTS: Respective angular, entry, and apex deviation values of 1.563 ± 0.977°, 0.725 ± 0.268 mm, and 0.808 ± 0.284 mm were calculated for all included implants, with corresponding values of 1.388 ± 1.090°, 0.789 ± 0.285 mm, and 0.846 ± 0.301 mm in the active group and 1.739 ± 0.826°, 0.661 ± 0.236 mm, and 0.769 ± 0.264 mm in the passive group. Only angular deviation differed significantly among groups, and the registration area was not associated with any significant differences among groups. CONCLUSIONS: Passive and active dynamic navigation approaches can achieve comparable in vitro accuracy. Registration on one side of the missing single posterior tooth area in the mandible can complete single-tooth implantation on both sides of the posterior teeth, highlighting the promise of further clinical research focused on this topic.

Accuracy of automatic and manual dynamic navigation registration techniques for dental implant surgery in posterior sites missing a single tooth: A retrospective clinical analysis.

OBJECTIVES: To assess the relative accuracy of manual (U-shaped tube) and automatic (two-in-one) dynamic navigation registration techniques for implant surgery performed in posterior sites missing one tooth. MATERIALS AND METHODS: This study included 58 partially edentulous patients with 58 implants, including 31 and 27 in the manual and automatic groups. Deviations between the planned and actual implant placement were assessed. RESULTS: The angular deviation in the overall study cohort was 2.54 ± 1.21°, while the 3D deviations at the implant platform and apex were 0.90 ± 0.46 mm and 1.04 ± 0.47 mm, respectively. The respective angular deviations in the manual and automatic groups were 2.82 ± 1.17° and 2.21 ± 1.19° (p > .05), while platform deviations were 0.89 ± 0.48 mm and 0.91 ± 0.45 mm (p > .05), and apex deviations were 0.99 ± 0.48 mm and 1.11 ± 0.46 mm (p > .05). No significant differences in absolute buccolingual, mesiodistal, or apicocoronal deviations were detected between these groups at either level (p > .05) nor were did deviation distributions differ in the buccolingual, mesiodistal, or apicocoronal directions at the platform or apex levels (p > .05). CONCLUSIONS: Manual and automatic dynamic navigation registration techniques can achieve excellent accuracy when placing implants in posterior sites missing a single tooth. The two-in-one automatic registration technique can reduce the amount of time and intraoperative steps necessary to complete the registration process relative to the manual U-shaped tube registration technique. Further follow-up studies are necessary to expand on these results.

A registration-and-fixation approach with handpiece adjustment for dynamic navigation in dental implant surgery.

The deviations between the preoperative (planned) and postoperative (actual) positions of dental implants have always been of a major concern in dental implant surgery. Dynamic computer-aided implant surgery (dCAIS) systems have been used to achieve optimal implant positioning. The method of registration is indeed an important factor that affects the implanting accuracy. Here, we propose a fast and concise registration method using a registration-and-fixation device as well as an adjustable handpiece for dynamic navigation in dental implant surgery. To the best of our knowledge, our work is the first study of such a registration method for dynamic navigation in a dental implant system.

Costochondral Graft in Young Children With Hemifacial Microsomia.

Patients with severely hypoplastic mandibles usually require condylar reconstruction. This study aimed to describe costochondral graft (CCG) for condylar reconstruction and report subsequent outcomes of these grafts in young children with Pruzansky/Kaban type IIB and type III mandibular hypoplasia. This study included 4 young children with type IIB and type III hemifacial microsomia treated with CCG to reconstruct the condyle at the Department of Oral and Maxillofacial Surgery in our hospital from March 2008 to March 2014. Radiographic measurements and clinical examinations were conducted. The mean age of patients at operation was 3.8 years, ranging from 2.8 to 5.3 years. The mean follow-up period was 43.5 months, ranging from 23 to 63 months. Functional improvement was observed in all patients. The ribs had grown in all patients to date. Three patients had clinically improved face appearance with no significant chin point deviation and canting of the occlusal plane. Although the other patient had partly improved face appearance compared with preoperative condition, he still showed clinically significant facial asymmetry and chin deviation. Our results showed that condylar reconstruction with CCG is a feasible method in the treatment of type IIB and type III hemifacial microsomia in young children. These results will provide early preliminary suggestions of growth and stability of CCG in patients <5 years.

Primary neuroendocrine carcinoma in oral cavity: two case reports and review of the literature.

Neuroendocrine carcinoma (NEC) is a tumor that occurs in different locations, particularly the lungs and larynx. The oral cavity is a rare site for a primary NEC. This report describes 2 cases of primary NEC in the oral cavity. Case 1 occurred in the anterior mandibular gingiva in a 25-year-old woman and presented with a special histologic appearance. This patient showed no evidence of recurrence 13 months after marginal resection of the anterior mandible. Case 2 was a primary NEC with some foci of squamous cell differentiation arising in the right buccal region in a 38-year-old woman. This patient showed no evidence of disease 8 months after tumor resection and postoperative iodine-125 brachytherapy. To the best of the authors' knowledge, case 1 is the youngest patient with NEC reported in the oral cavity to date in the English-language literature, and case 2 is the first report of a primary NEC in the buccal region.