Kiyoshi Tai

Preliminary cone-beam computed tomography study evaluating dental and skeletal changes after treatment with a mandibular Schwarz appliance

INTRODUCTION The purpose of this study was to evaluate the efficacy of the Schwarz appliance with a new method of superimposing detailed cone-beam computed tomography (CBCT) images. METHODS The subjects were 28 patients with Angle Class I molar relationships and crowding; they were randomly divided into 2 groups: 14 expanded and 14 nonexpanded patients. Three-dimensional Rugle CBCT software (Medic Engineering, Kyoto, Japan) was used to measure 10 reference points before treatment (T0) and during the retention period of approximately 9 months after 6 to 12 months of expansion (T1). Cephalometric and cast measurements were used to evaluate the treatments in both groups. Also, the mandibular widths of both groups were measured along an axial plane at 2 levels below the cementoenamel junction from a CBCT scan. Differences between the 2 groups at T0 and T1 were analyzed by using the Mann-Whitney U test. RESULTS The dental arch (including tooth root apices) had expanded; however, alveolar bone expansion was only up to 2 mm below the cementoenamel junction. There was a statistically significant (P <0.05) difference between the groups in terms of crown, cementoenamel junction, root, and upper alveolar process. However, no significant (P >0.05) differences were observed in the interwidths of the mandibular body, zygomatic bones, condylar heads, or mandibular antegonial notches. In the mandibular cast measurements, arch crowding and arch perimeter showed statistically significant changes in the expanded group. The buccal mandibular width and lingual mandibular width values had significant changes as measured from a point 2 mm below the cementoenamel junction. CONCLUSIONS The findings suggest that the Schwarz appliance primarily affected the dentoalveolar complex, but it had little effect on either the mandibular body or any associated structures. In addition, the molar center of rotation was observed to be below the root apex.

3-Dimensional cone-beam computed tomography analysis of transverse changes with Schwarz appliances on both jaws.

OBJECTIVE To evaluate transverse changes from Schwarz appliances on both jaws in young, growing patients using cone-beam computed tomography (CBCT). MATERIALS AND METHODS All subjects had Angle Class I molar relationships and crowding. They were randomly divided into two groups; 30 expanded and 30 control subjects. Three-dimensional CBCT software was used to evaluate and compare treatment effects between the groups. To test for any significant differences between groups at T0 and T1, an independent t-test and paired t-tests were used. RESULTS The interbuccal dentoalveolar width (BDAW), interpalatal dentoalveolar width (PDAW), and interlingual dentoalveolar width (LDAW) values showed significant changes when measured from a point 3 mm coronal to the cementoenamel junction (CEJ) to 8 mm apical to the CEJ. When compared with mandibular interdentoalveolar width differences (BDAW-LDAW), significant differences (P < .05) were observed. The soft tissue width of the maxillary and mandibular teeth and alveolar bone showed no significant changes (P > .05), even with dentoalveolar arch expansion in both jaws. CONCLUSIONS This study indicates that Schwarz appliances primarily affect the dentoalveolar complex and have varying effects on mandibular and maxillary alveolar bone width. Also, soft tissue is not affected in the area of expansion in this research.

Orthodontic Treatment of a Congenitally Missing Maxillary Lateral Incisor

UNLABELLED Clinicians agree that, regardless of gender or race, tooth agenesis has become more prominent in recent societies. The congenital absence of one or more maxillary lateral incisors poses a challenge to effective treatment planning for the restorative dentist. However, the one-sided orthodontic approach of just moving canines mesially to eliminate restorative procedures leads to compromise. Adult patients presenting with malocclusions, missing lateral incisors, or anterior crowding but who fail to get proper orthodontic treatment, requesting instead esthetic solutions that do not establish a stable occlusion, proper alignment, and proper axial inclination of the teeth will have compromised esthetic and periodontal results. An evaluation of anterior smile esthetics must include both static and dynamic evaluations of frontal and profile views to optimize both dental and facial appearance. This article presents how orthodontics is combined with other specialties in treating a congenitally missing lateral incisor. One case is used to illustrate how orthodontic treatment is progressed in collaboration with other specialists. CLINICAL SIGNIFICANCE Patients with missing teeth, crowding, midline deviation, unesthetic gingival contours, or other restorative needs may require the interaction between various specialists. For the successful treatment of orthodontic-restorative patients, an interdisciplinary team effort is vital.

Distal movement of the mandibular dentition with temporary skeletal anchorage devices to correct a Class III malocclusion

This case report describes the treatment of an 18-year-old man with a skeletal Class III pattern and a full-step Class III malocclusion. The orthodontic treatment included distal movement of the mandibular dentition with temporary skeletal anchorage devices. The total active treatment time was 30 months. His occlusion and facial appearance were significantly improved by the orthodontic treatment. Posttreatment records 2 years later showed excellent results with good occlusion and facial balance.

Severe facial asymmetry and unilateral lingual crossbite treated with orthodontics and 2-jaw surgery: 5-year follow-up

A 33-year-old woman with severe facial asymmetry and unilateral lingual crossbite was treated with orthodontics combined with differential maxillary impaction and intraoral vertical ramus osteotomy. After 12 months of preoperative orthodontic treatment, 2-jaw surgery was performed. The total active treatment time was 18 months. Both her occlusion and facial appearance were significantly improved by the surgical-orthodontic treatment. The occlusion was stable after 5 years of retention. Posttreatment records after 5 years showed excellent results with good occlusion and long-term stability.

Space closure in the maxillary posterior area through the maxillary sinus.

A common dilemma in adult orthodontic treatment is deciding how best to treat missing posterior teeth. One treatment option is to orthodontically close the space. But closure can be difficult, especially if the open space is in the maxillary posterior area, because tooth movement through the maxillary sinus is limited. The increased difficulty of moving teeth in the maxillary sinus is similar to moving a tooth in the atrophic posterior mandibular ridge. If space closure is selected as a treatment method, proper mechanics and light forces should be applied. In this article, we report movement of teeth through the maxillary sinus and discuss various implications related to orthodontic treatment in the maxillary sinus.

Orthodontic treatment for a patient with a unilateral cleft lip and palate and congenitally missing maxillary lateral incisors and left second premolar

Treatment of a patient with a cleft lip and palate can be challenging. A woman, aged 26 years 8 months, was referred for orthodontic evaluation of her anterior crossbite. She was unhappy with the unesthetic appearance of her maxillary anterior teeth, which were behind her mandibular anterior teeth. She had a unilateral cleft lip and palate and had received primary lip repair and palatoplasty when she was younger, as well as rhinoplasty and a secondary lip repair when she was 15. At the pretreatement evaluation, she had a concave profile with an overjet of -9 mm, a Wits appraisal of -3.8 mm, and a transposed ectopic maxillary right canine. She was treated with orthodontic treatment alone, without orthognathic surgery. The posttreatment records 9 years later showed excellent results with good occlusion, facial balance and harmony, and long-term stability.

Esthetic orthodontic treatment with a double J retractor and temporary anchorage devices

This clinical article reports an esthetic treatment option for managing a Class II malocclusion in an adult. The patient, a woman aged 24 years 2 months, had crowding and a convex profile. She was treated with maxillary first premolar extractions, a double J retractor, and temporary skeletal anchorage devices in the maxillary arch. Posttreatment records after 2 years showed excellent results with good occlusion and long-term stability.

Unilateral delayed eruption of a mandibular permanent canine and the maxillary first and second molars, and agenesis of the maxillary third molar.

Delayed tooth eruption can affect the accuracy of orthodontic diagnosis and treatment planning and could delay overall treatment. A girl, aged 7 years 4 months, who had unilateral delayed eruption of several teeth was successfully treated. The evaluation of delayed tooth eruption should be considered by the orthodontist because the role of these teeth can affect the overall treatment of malocclusion. In patients with delayed tooth eruption, careful and accurate diagnosis and treatment planning will allow the orthodontist to start treatment at the proper stage and might reduce the overall orthodontic treatment time.

Prediction of optimal bending angles of a running loop to achieve bodily protraction of a molar using the finite element method

Objective The purpose of this study was to predict the optimal bending angles of a running loop for bodily protraction of the mandibular first molars and to clarify the mechanics of molar tipping and rotation. Methods A three-dimensional finite element model was developed for predicting tooth movement, and a mechanical model based on the beam theory was constructed for clarifying force systems. Results When a running loop without bends was used, the molar tipped mesially by 9.6° and rotated counterclockwise by 5.4°. These angles were almost similar to those predicted by the beam theory. When the amount of tip-back and toe-in angles were 11.5° and 9.9°, respectively, bodily movement of the molar was achieved. When the bend angles were increased to 14.2° and 18.7°, the molar tipped distally by 4.9° and rotated clockwise by 1.5°. Conclusions Bodily movement of a mandibular first molar was achieved during protraction by controlling the tip-back and toe-in angles with the use of a running loop. The beam theory was effective for understanding the mechanics of molar tipping and rotation, as well as for predicting the optimal bending angles.