3D printed coping for intraoral evaluation: a clinical report.

The clinical report describes a three-dimensional (3D) printed coping for intraoral evaluation before milling final anterior restorations. The use of printed copings allows restorations for complex and esthetically important restorations to be thoroughly tested at relatively low cost without introducing large delays into the fabrication process.

Dense cancellous bone as evidenced by a high HU value is predictive of late implant failure: a preliminary study.

OBJECTIVES: The mechanism of late implant failure is unclear. This study examined the association between sclerosing cancellous bone images and the risk of late implant failures using multi-detector row computed tomography (CT) imaging data. METHODS: We performed a case-control study. The study group consisted of consecutive patients with implant failures treated at Kyushu Dental University between 2001 and 2016. CT data for late failure of 36 implants in 16 patients were available. The study cohort consisted of 16 patients with 36 late failed implants and 28 patients with 113 successful implants. RESULTS: The mean survival rate was 6.9 months for early implant failure, 76.6 months for late failure with marginal bone resorption, inflammation symptoms, and so-called peri-implantitis, and 95.0 months for late failure caused by implant fracture. The mean HU value for cases in the control group was 507 compared with 1231 for cases with late failure implants. Logistic regression was used for analysis. There were signs of high radiodensity of peri-implant cancellous bone when comparing adjusted radiodensity per 100 HU using CT data (OR 2.35; 95% CI 1.73-3.20; p < 0.001). CONCLUSIONS: Within the limits of our study, the presence of high radiodensity and cancellous bone consolidation on imaging may be related to risk factors for late implant failure. Therefore, CT images of the host cancellous bone status for observation of visible sclerosis could be a useful diagnostic indicator for late implant failure.

Measurement accuracy of alveolar soft tissue contour using a laboratory laser scanner.

Steric analysis of morphological changes is important for evaluation of surgical techniques. This study was performed to assess the measurement accuracy of alveolar soft tissue contour with a laboratory laser scanner. The width of the maxillary alveolar soft tissue contour was evaluated in 20 volunteers. Measurement sites were established in the alveolar soft tissue contour of the maxillary incisor and canine areas. Each site was evaluated by direct measurement with a microcaliper for each subject (DMM) and image measurement using a laboratory laser scanner (IMS). The accuracy of measurement methods was evaluated. Additionally, two plaster models obtained from the same subjects were scanned and superimposed, and the nonoverlapping areas were measured. Each measurement method exhibited a strong correlation (r = 0.89). The interclass correlation coefficient (single measure) between examiners was also high for each measurement method (PMM 0.978; IMS 0.997). In the superimposed images of the two plaster models, the distance of the nonoverlapping region was only 0.06 ± 0.08 mm in the labial aspect and 0.07 ± 0.09 mm in the palatal aspect. The image measurement of the scanning data shows high accuracy in evaluation of the alveolar soft tissue contour. This technique is useful for evaluation of chronological changes in the alveolar contour after soft and hard tissue augmentation.

Relationship between cortical bone thickness and implant stability at the time of surgery and secondary stability after osseointegration measured using resonance frequency analysis.

PURPOSE: It has been suggested that resonance frequency analysis (RFA) can measure changes in the stability of dental implants during osseointegration. This retrospective study aimed to evaluate dental implant stability at the time of surgery (primary stability; PS) and secondary stability (SS) after ossseointegration using RFA, and to investigate the relationship between implant stability and cortical bone thickness. METHODS: In total, 113 patients who attended the Tohoku University Hospital Dental Implant Center were included in this study. A total of 229 implants were placed in either the mandibular region (n=118) or the maxilla region (n=111), with bone augmentation procedures used in some cases. RFA was performed in 3 directions, and the lowest value was recorded. The preoperative thickness of cortical bone at the site of implant insertion was measured digitally using computed tomography, excluding cases of bone grafts and immediate implant placements. RESULTS: The mean implant stability quotient (ISQ) was 69.34±9.43 for PS and 75.99±6.23 for SS. The mandibular group had significantly higher mean ISQ values than the maxillary group for both PS and SS (P<0.01). A significant difference was found in the mean ISQ values for PS between 1-stage and 2-stage surgery (P<0.5). The mean ISQ values in the non-augmentation group were higher than in the augmentation group for both PS and SS (P<0.01). A weak positive correlation was observed between cortical bone thickness and implant stability for both PS and SS in all cases (P<0.01). CONCLUSIONS: Based on the present study, the ISQ may be affected by implant position site, the use of a bone graft, and cortical bone thickness before implant therapy.

Sandwich bone graft for vertical augmentation of the posterior maxillary region: a case report with 9-year follow-up.

The loss of teeth followed by bone resorption often lead to defects in the alveolar ridge, making installation of dental implants difficult. Correction of such bone defects, especially lack of height of the ridge, is a difficult problem for all dental surgeons. This report describes the outcome of treatment after alveolar ridge augmentation in the atrophic posterior maxillary region via segmental sandwich osteotomy combined with placement of an interpositional autograft prior to placement of endosseous implants. The technique was successfully used to treat a deficiency in the vertical dimension of the posterior maxillary region. Six months after graft surgery, two implants were successfully placed in accordance with the original treatment protocol, and they survived for 9 years of follow-up.

Removal of dental implant displaced into maxillary sinus by combination of endoscopically assisted and bone repositioning techniques: a case report.

BACKGROUND: Accidental displacement of a dental implant into the maxillary sinus is an infrequent although not uncommon complication encountered in dental clinical practice, with the main cause thought to be inadequate bone height in the posterior maxilla. We report a case of migration of a dental implant into the maxillary sinus, and discuss the benefits of its removal by a combination of endoscopically assisted and bone repositioning techniques. CASE PRESENTATION: A 35-year-old Japanese man with a partially edentulous maxilla underwent implant placement at a private clinic. Three months later, at the time of abutment connection, the implant at the site of his maxillary right first molar was accidentally pushed into the sinus. The hole on the alveolar ridge made for placement of the implant was small and far from the dislocated implant, thus access was achieved in a transoral manner via the frontal wall of his maxillary sinus with an endoscopic approach. Piezoelectric instruments were used to perform an osteotomy. The bone lid was removed, and the implant was identified using a rigid endoscope and removed with a surgical aspirator, followed by repositioning of the bony segment; the area was secured with an absorbable suture. Removal of migrated implants should be considered in order to prevent possible sinusal disease complications. CONCLUSIONS: In the present case, removal of a dental implant displaced into the maxillary sinus by use of a combination of endoscopically assisted and bone repositioning techniques proved to be a safe and reliable procedure.

The Effect of Decortication for Periosteal Expansion Osteogenesis Using Shape Memory Alloy Mesh Device.

BACKGROUND: In conventional bone grafting technique, decortication procedure enhances the healing process and bone regeneration to reach the grafted site more readily. PURPOSE: This study evaluates to improve periosteal expansion osteogenesis (PEO) using a shape memory alloy mesh (SMA) device with decortication in a rabbit model. MATERIALS AND METHODS: The SMA device was inserted under the periosteum at the forehead and pushed, bent, and attached to the bone surface and fixed with a titanium screw. Twelve rabbits were divided into two groups: PEO without decortication (P group) and with decortication (D group). After 2 weeks, the screw was removed, and the mesh was activated by its own elasticity. Rabbits were sacrificed 5 (P1/D1) and 8 (P2/D2) weeks after operation and histologically and radiographically evaluated. RESULTS: The mean activation height was 2.9 ± 0.5 mm. The ratio of new bone volume in the elevated volume was 17.6% in P1, 59.8% in D1 33.4% in P2, and 65.1% in D2. D group had a statistically higher volume of new bone than P group during each period (p < .05). CONCLUSION: PEO with decortication appears to be a promising clinical alternative for bone augmentation and introduces the new concept of "dynamic graft and guided bone regeneration (GBR)."

Elderly patients with maxillofacial trauma: study of mandibular condyle fractures.

BACKGROUND/AIM: The aim of this study was to investigate the trends and characteristic features of mandibular condyle fractures in elderly patients in terms of etiology, patterns, and treatment modalities. PATIENTS AND METHODS: Records of 201 patients aged 65 years and older, who were treated for maxillofacial fractures at the Department of Oral and Maxillofacial Surgery, Kyushu Dental University, and Tohoku University from January 2002 to December 2013, were retrospectively analyzed. Patient records and radiographs were examined, with the following information: relevant medical history, cause of fracture, the presence and state of premolars and molars in the maxilla and mandible, number and location of mandible fracture, and method of treatment. As for the state of premolars and molars, premolars or molars in the mandible in contact with the maxilla were regarded as contacted. RESULTS: A fall was responsible for the majority of the fractures (173/201). With condyle fractures, there was a significant difference between the contacted and non-contacted group in regard to incidence. Furthermore, there was a significantly greater number of cases with symphysis and condyle combination fractures in the non-contacted group (70.9%) than in the contacted group (51.9%). As for the method of treatment, arthrocentesis was the most commonly employed. CONCLUSIONS: The present findings suggest that contacted molars in the maxilla and mandible have an influence on condyle fractures in elderly individuals.

Self-activated mesh device using shape memory alloy for periosteal expansion osteogenesis.

The present study evaluated the use of this self-activated shape memory alloy (SMA) device, with a focus on its effects in the region under the periosteum. Twelve Japanese white rabbits were used in this study. The device was inserted under the periosteum at the forehead. In the experimental group, the device was pushed, bent, and attached to the bone surface and fixed with a titanium screw. In control group, the device was only inserted under the periosteum. After 14 days, the screw was removed and the mesh was activated in the experimental group. Rabbits were sacrificed 5 and 8 weeks after the operation and newly formed bone was histologically and radiographically evaluated. The quantitative data by the area and the occupation of newly formed bone indicated that the experimental group had a higher volume of new bone than the control group at each consolidation period. Histologically, some newly formed bone was observed and most of the subperiosteal space underneath the device was filled with fibrous tissue, and a thin layer of immature bone was observed in the control group. In the experimental group, multiple dome-shaped bones, outlined by thin and scattered trabeculae, were clearly observed under the SMA mesh device. The use of self-activated devices for the periosteal expansion technique may make it possible to avoid donor site morbidity, trans-skin activation rods, any bone-cutting procedure, and the following intermittent activation procedure.