Masako Tabuchi

Accurate pre-surgical determination for self-drilling miniscrew implant placement using surgical guides and cone-beam computed tomography

Miniscrew implants have proven to be effective in providing absolute orthodontic anchorage. However, as self-drilling miniscrew implants have become more popular, a problem has emerged, i.e. root contact, which can lead to perforation and other root injuries. To avoid possible root damage, a surgical guide was fabricated and cone-beam computed tomography (CBCT) was used to incorporate guide tubes drilled in accordance with the planned direction of the implants. Eighteen patients (5 males and 13 females; mean age 23.8 years; minimum 10.7, maximum 45.5) were included in the study. Forty-four self-drilling miniscrew implants (diameter 1.6, and length 8 mm) were placed in interradicular bone using a surgical guide procedure, the majority in the maxillary molar area. To determine the success rates, statistical analysis was undertaken using Fishers exact probability test. CBCT images of post-surgical self-drilling miniscrew implant placement showed no root contact (0/44). However, based on CBCT evaluation, it was necessary to change the location or angle of 52.3 per cent (23/44) of the guide tubes prior to surgery in order to obtain optimal placement. If orthodontic force could be applied to the screw until completion of orthodontic treatment, screw anchorage was recorded as successful. The total success rate of all miniscrews was 90.9 per cent (40/44). Orthodontic self-drilling miniscrew implants must be inserted carefully, particularly in the case of blind placement, since even guide tubes made on casts frequently require repositioning to avoid the roots of the teeth. The use of surgical guides, fabricated using CBCT images, appears to be a promising technique for placement of orthodontic self-drilling miniscrew implants adjacent to the dental roots and maxillary sinuses.

Enhancement of Crude Bone Morphogenetic Protein-Induced New Bone Formation and Normalization of Endochondral Ossification by Bisphosphonate Treatment in Osteoprotegerin-Deficient Mice

Osteoprotegerin (OPG) is a novel secreted member of the tumor necrosis factor receptor family which plays a crucial role in negative regulation of osteoclastic bone resorption. We investigated both the quantity and quality of heterotopic new bone induced by crude bone morphogenetic protein (BMP) as a means of examining bone metabolism by bisphosphonate administration in OPG−/− mice. Four weeks after implantation of crude BMP, the volume of heterotopic new bone in OPG−/− mice without alendronate was significantly less than in wild-type (WT) mice. Alendronate treatment of OPG−/− mice resulted in enhancement of the volume of heterotopic new bone. Histological findings revealed that WT mice showed normal bone formation with persistent cartilage that was interspersed with islands of bone. In contrast, the cartilage was replaced by trabecular bone and bone marrow adipocytes in OPG−/− mice without alendronate. However, some cartilage was still present in OPG−/− mice with alendronate compared to those without alendronate. All bone formation-related parameters and bone resorption-related parameters were significantly lower in OPG−/− mice with alendronate than in those without alendronate. These findings suggest that in stimulated osteoclastogenesis without OPG, osteoinductive activity induced by crude BMP is inhibited and endochondral ossification induced by crude BMP is accelerated. On the other hand, alendronate treatment of OPG−/− mice caused osteoinductive activity induced by crude BMP to increase and endochondral ossification induced by crude BMP to be decelerated. In conclusion, inhibition of stimulated osteoclastogenesis results in the enhancement of new bone formation and normalization of endochondral ossification.

Effectiveness of en-masse retraction using midpalatal miniscrews and a modified transpalatal arch: Treatment duration and dentoskeletal changes

Objective The purpose of this study was to compare the treatment duration and dentoskeletal changes between two different anchorage systems used to treat maxillary dentoalveolar protrusion and to examine the effectiveness of en-masse retraction using two miniscrews placed in the midpalatal suture. Methods Fifty-seven patients (9 men, 48 women), who had undergone level anchorage system treatment at Aichi-Gakuin University Dental Hospital (Nagoya, Japan) were divided into two groups according to the method of maxillary posterior anchorage reinforcement: midpalatal miniscrews (25 patients, mean age 22 years) and conventional anchorage (32 patients, mean age 19 years). The en-masse retraction period, overall treatment duration, pre-treatment effective ANB angle, and change in the effective ANB angle were compared with an independent-samples t-test. Results Compared to the headgear group, the duration of en-masse retraction was longer by approximately 4 months in the miniscrew group (p < 0.001). However, we found no significant difference in the total treatment duration between the groups. Moreover, a greater change in the effective ANB angle was observed in patients treated with miniscrews than in those treated with the conventional method (p < 0.05). Conclusions The level anchorage system treatment using miniscrews placed in the midpalatal area will allow orthodontists more time to control the anterior teeth during en-masse retraction, without increasing the total treatment duration. Furthermore, it achieves better dentoskeletal control than does the conventional anchorage method, thereby improving the quality of the treatment results.

Effect of Reveromycin A on Experimental Tooth Movement in OPG−/− Mice

In osteoprotegerin-deficient (OPG−/−) mice, osteoclast activity causes bone resorption to outpace bone formation, leading to the development of severe osteoporosis. Such mice are therefore useful for investigating the alveolar bone of patients with osteoporosis. Reveromycin A (RM-A) was recently identified as the unique agent acting on osteoclast activation. This study aimed to analyze the effect of RM-A on the orthodontic treatment of OPG−/− mice (a model of osteoporosis patients with high levels of bone turnover). We examined alveolar bone remodeling in OPG−/− and wild-type (WT) mice during continuous tooth movement. The orthodontic force was induced by means of a Ni-Ti closed-coil spring to move the maxillary first molar for 14 days. RM-A sodium salt (1 mg/kg) was administered intraperitoneally twice daily. In OPG−/− mice, the tooth movement distance was longer, alveolar bone resorption was enhanced, the osteoclast count was greater, and serum alkaline phosphatase and tartrate-resistant acid phosphatase levels were higher relative to those in WT mice. However, the administration of RM-A in OPG−/− mice reduced these parameters. We conclude that RM-A normalizes bone metabolism and loss of alveolar bone during continuous tooth movement in OPG−/− mice.

Stabilization of tooth movement by administration of reveromycin A to osteoprotegerin-deficient knockout mice.

INTRODUCTION In this study, mechanical stress in the form of tooth movement was applied to osteoprotegerin-deficient knockout mice, which served as an animal model for juvenile Pagets disease. To compare and evaluate bone turnover and response of the surrounding bony tissue, we administered reveromycin A. We also investigated the ability of reveromycin A to control osteoclastic activity in juvenile Pagets disease. METHODS Eight-week-old male osteoprotegerin-deficient knockout and wild-type mice were injected with reveromycin A (15 mg/kg of body weight) intraperitoneally twice daily. An elastic module was inserted interproximally between the maxillary left first and second molars. RESULTS Administration of reveromycin A to osteoprotegerin-deficient knockout mice reduced tooth movement distances, increased bone volumes at the interradicular septum, decreased osteoclast counts, and reduced serum alkaline phosphatase and tartrate resistant acid phosphatase. Reveromycin A administration also caused a temporal shift in peak Runx2 staining in osteoprotegerin-deficient knockout mice so that the overall staining time course was similar to that observed for wild-type mice. CONCLUSIONS Reveromycin A administration in osteoprotegerin-deficient knockout mice inhibited bone resorption and normalized bone formation. As a result, normal bone turnover was obtained.

Reveromycin A Administration Prevents Alveolar Bone Loss in Osteoprotegerin Knockout Mice with Periodontal Disease.

Chronic periodontal disease is characterized by alveolar bone loss and inflammatory changes. Reveromycin A (RMA) was recently developed and is a unique agent for inhibiting osteoclast activity. This study analysed the effects of RMA in an experimental mouse model of periodontitis involving osteoprotegerin (OPG)-knockout mice, specifically, whether it could control osteoclasts and reduce inflammation in periodontal tissue. We examined wild-type (WT) and OPG knockout mice (OPG KO) ligated with wire around contact points on the left first and second molars. RMA was administered twice a day to half of the mice. Using micro-computed tomography, we measured the volume of alveolar bone loss between the first and second molars, and also performed histological analysis. The OPG KO RMA+ group had significantly decreased osteoclast counts, alveolar bone loss, attachment loss, and inflammatory cytokine expression 8 weeks after ligation. Thus, RMA may reduce alveolar bone loss and inflamed periodontal tissues in patients with periodontitis.

Effect of UV Photofunctionalization on Biologic and Anchoring Capability of Orthodontic Miniscrews.

PURPOSE Treatment of titanium with UV light immediately before use, or photofunctionalization, is gaining traction as a simple method to improve the biologic capability and clinical performance of dental implants. The objective of this study was to examine the effect of photofunctionalization on the biologic capability and mechanical anchorage of orthodontic miniscrews. MATERIALS AND METHODS Untreated and photofunctionalized Ti-6Al-4V orthodontic miniscrews were placed into rat femurs. Photofunctionalization was performed by treating miniscrews with UV light for 12 minutes using a photo device immediately before placement. After 3 weeks of healing, miniscrews were pushed laterally to measure the resistance against the tipping force. The miniscrews were also evaluated for morphology and chemistry of tissue formed around them using scanning electron microscopy and energy dispersive spectroscopy. Rat bone marrow-derived osteoblasts were cultured on Ti-6Al-4V disks with and without photofunctionalization. The number of osteoblasts attached to the disks and the behaviors, alkaline phosphatase activity, and mineralization capability of osteoblasts were evaluated. RESULTS Photofunctionalization converted both disk and screw surfaces from hydrophobic to superhydrophilic. In vivo biomechanical testing showed that the displacement of untreated screws was 1.5 to 1.7 times greater than that of photofunctionalized screws when subjected to lateral tipping force. Robust bone formation was observed around photofunctionalized miniscrews with strong elemental peaks of calcium and phosphorus, whereas the tissue around untreated miniscrews appeared thin and showed no clear peak of calcium. The attachment, initial spreading, adhesion, and expression of functional phenotypes of osteoblasts were significantly increased on photofunctionalized Ti-6Al-4V disks. CONCLUSION These in vivo and in vitro results comprehensively and consistently demonstrate that photofunctionalization increases the bioactivity of Ti-6Al-4V and improves the anchoring capability of orthodontic miniscrews.

Questionnaire survey on pain and discomfort after insertion of orthodontic buccal miniscrews, palatal miniscrews and, orthodontic miniplates

Abstract Purpose Skeletal anchorage devices have recently been developed for absolute anchorage during edgewise treatment. Such anchorage devices can be divided into miniplate and miniscrew types. However, the differences between these two types of appliance have not been sufficiently evaluated from the patients point of view. Therefore, we surveyed patients for two weeks after insertion of miniplates and miniscrews in order to evaluate their pain and discomfort. Materials and methods Sixty-four patients were divided into the following three groups: maxillary buccal miniplate (Group A) (19 people, 38 plates); upper buccal miniscrew (Group B) (14 people, 27 screws); and maxillary palatal miniscrew (Group C) (31 people, 49 screws). All participants completed questionnaires for 14 days after the operation. The patients responded to questions by placing a mark along a 10-cm-long visual analog scale (VAS). Results There were no significant differences in pain and discomfort due to the orthodontic archwire itself, as opposed to the anchorage devices, between all three groups. However, Group A showed significantly higher levels of pain and discomfort after insertion than both miniscrew groups at all periods, and Group C presented prolonged discomfort relative to Group B. At three days after operation, more than 35% in Group A were taking analgesics, compared to significantly lower percentages in Group C (0%) and Group B (7.1%). Conclusion These results suggest that appropriate skeletal anchorage devices should be selected on a case-by-case basis, considering not only the mechanical effect but also the patients’ pain and discomfort levels.

Insertion torque and Periotest values are important factors predicting outcome after orthodontic miniscrew placement

Introduction Approximately 14% of orthodontic anchor screws (miniscrews) become dislodged regardless of the accuracy of placement. It is therefore important to investigate the factors causing dislodgement. We evaluated the stability of miniscrews after placement to identify factors influencing outcome in orthodontic treatment using miniscrews. Methods We investigated 120 miniscrews (Dual‐top Auto Screw III; Jeil Medical, Seoul, Korea) (diameter, 1.4 mm; length, 6 mm) placed on the buccal or lingual side between the maxillary second premolar and the first molar in women. Patient age and rate and time of screw dislodgement were examined. Insertion torque values and Periotest (Tokyo Dental Industrial, Tokyo, Japan) measurements indicating horizontal and vertical mobility of the inserted screws were compared between groups with and without dislodgement (failure and success groups, respectively). Results Mean insertion torque values were 10.7 ± 1.9 N·cm and 8.5 ± 2.1 N·cm in the failure and success groups, respectively. Cortical bone thickness measurements (success group, 1.34 ± 0.35 mm; failure group, 0.99 ± 0.09 mm) were significantly higher, whereas Periotest values at placement (success group, horizontal, 4.9 ± 1.4; vertical, 4.7 ± 1.3; failure group, horizontal, 7.0 ± 0.8; vertical, 7.1 ± 0.9) were significantly lower in the success group than in the failure group. Conclusions The Periotest value, together with insertion torque and cortical bone thickness, could serve as an index of initial stability for predicting the outcome of miniscrew placement. HighlightsAppropriate insertion torque values obtain good stability after miniscrew placement.Failure rate significantly increases when cortical bone thickness is ≤1 mm.Periotest values at placement were significantly higher in the failure group.Periotest instead of CBCT may give an initial stability index for miniscrew outcome.

Skeletal Class III Malocclusion with Unilateral Congenitally Missing Maxillary Incisor Treated by Maxillary Protractor and Edgewise Appliances

This case report describes the orthodontic treatment of a 10-year-old female patient with a combination of Angle Class III malocclusion, a missing maxillary right lateral incisor, a supernumerary tooth with a short root on the lingual side of the maxillary incisor, a skeletal Class III jaw base relationship caused by a diminutive maxilla, and retroposition of the maxilla. We chose to close the space of the missing tooth, as well as the space created by extraction of the maxillary lateral incisor, by forward movement of the canine and premolars using a maxillary protractor with edgewise appliances. As a result, both the maxillary premolars and the molars were moved mesially, and a Class II molar relationship with tight interdigitation was achieved. Our results suggest that the combination of maxillary protractor and nontorque brackets was effective not only for correcting skeletal Class III malocclusion, but also for forward movement of the maxillary posterior teeth.