A new rationale for preservation of the mandibular third molar in orthognathic patients with missing molars.

Controversies exist regarding the need for prophylactic extraction of mandibular third molars in patients who plan to undergo orthognathic surgery. An 18-year-old male patient was diagnosed with mandibular prognathism and maxillary retrognathism with mild facial asymmetry. He had a severely damaged mandibular first molar and a horizontally impacted third molar. After extraction of the first molar, the second molar was protracted into the first molar space, and the third molar erupted into the posterior line of occlusion. The orthognathic surgery involved clockwise rotation of the maxillomandibular complex as well as angle shaving and chin border trimming. Patients who are missing or have damaged mandibular molars should be monitored for eruption of third molars to replace the missing posterior tooth regardless of the timing of orthognathic surgery.

Correcting severe scissor bite in an adult.

Scissor bite often remains unnoticed by patients although it can adversely affect facial symmetry, jaw growth, and mastication. This case report illustrates the efficacy of temporary skeletal anchorage devices (TSADs) and a modified lingual arch in correcting severe scissor bite. A 28-year-old woman presented with severe scissor bite in the mandibular right posterior segment. To treat this condition, TSADs were used for maxillary posterior intrusion and a modified lingual arch for buccally uprighting mandibular posterior teeth. Long-term retention records demonstrate stable treatment results.

Effect of "surgery first" orthognathic approach on temporomandibular symptoms and function: a comparison with "orthodontic first" approach.

OBJECTIVE: The aim of this study was to comparatively evaluate the effects of the surgery-first approach (SFA) and the orthodontics-first approach (OFA) on temporomandibular joint (TMJ) function and maximum mouth opening. STUDY DESIGN: This retrospective study investigated the outcomes of patients with diagnosed skeletal class III dentofacial deformities. Twenty-four patients were enrolled in the OFA group, and 23 patients were enrolled in the SFA group. All patients were examined in the same manner 4 times: before surgery and at 1, 3, 6, and 12 months after surgery. Range of mouth opening (ROM) was measured between the maxillary and mandibular central incisors. Symptoms were evaluated subjectively by using a questionnaire with items pertaining to pain on mandibular movements, TMJ sounds, and pain in masticatory muscles region. RESULTS: No severe complications or relapse occurred in either group during the 12-month follow-up period. Postoperative changes in ROM showed similar tendencies, but there was no significant difference in ROM during the follow-up period between the OFA and SFA groups (P < .05). The percentage reduction was nearly 45% at 1 month postoperatively and 20% at 3 months postoperatively compared with the preoperative situation. After 6 months postoperatively, the ROM was almost the same as before surgery. The number of patients with such sounds increased with time until 12-month postoperative examinations in the OFA group but increased slightly during this period in the SFA group. During the first 3 months postoperatively, less than 10% of patients in both groups had newly detected pain of TMJ and/or muscles. At 6 and 12 months postoperatively, only 1 patient in the SFA group had pain. CONCLUSIONS: No significant differences in TMJ symptoms or function were observed during a 12-month follow-up period between patients with skeletal class III malocclusion treated with the SFA and those treated with the OFA.

Envisioning Post-treatment Occlusions after Space Closure Using Temporary Skeletal Anchorage Devices.

Missing posterior teeth and posterior tooth extractions are commonly seen and needed within orthodontic practices. With the invention of temporary skeletal anchorage devices (TSADs), clinicians can now effectively close posterior tooth spaces. Various molar occlusions are discussed to help clinicians envision post-treatment occlusions after posterior teeth space closure using TSADs.

Change in alveolar bone level of mandibular second and third molars after second molar protraction into missing first molar or second premolar space.

OBJECTIVE: To investigate the factors associated with the change in alveolar bone level of mandibular second and third molars after second molar protraction into the space of the missing first molar (L6) or second premolar (LE). METHODS: Fifty-one patients in whom space of the missing L6 or LE was treated with second molar protraction (13 males, 38 females, mean age 19.6 ± 4.7 years) from 2003 to 2015 were included. The alveolar bone level and position and angulation of the mandibular second and third molars were measured in panoramic radiographs at pre-treatment (T1), and after the alignment of the third molars following second molar protraction (T2). Factors associated with alveolar bone loss on the distal aspect of the mandibular second molars were assessed using linear regression analysis. RESULTS: Age at T1 (P < 0.001) and third molar angulation at T1 (P = 0.002) were significant factors for the prediction of alveolar bone level distal to the second molars. LIMITATION: This study used two-dimensional panoramic radiographs, and we could observe only the interproximal bone level. CONCLUSIONS: After second molar protraction into the missing first molar or second premolar space, mandibular second molars may exhibit alveolar bone resorption in the distal root in older patients and in those with mesially tilted third molars before treatment.

Success rates of a skeletal anchorage system in orthodontics: A retrospective analysis.

OBJECTIVES: To evaluate the premise that skeletal anchorage with SAS miniplates are highly successful and predictable for a range of complex orthodontic movements. MATERIALS AND METHODS: This retrospective cross-sectional analysis consisted of 421 bone plates placed by one clinician in 163 patients (95 female, 68 male, mean age 29.4 years ± 12.02). Simple descriptive statistics were performed for a wide range of malocclusions and desired movements to obtain success, complication, and failure rates. RESULTS: The success rate of skeletal anchorage system miniplates was 98.6%, where approximately 40% of cases experienced mild complications. The most common complication was soft tissue inflammation, which was amenable to focused oral hygiene and antiseptic rinses. Infection occurred in approximately 15% of patients where there was a statistically significant correlation with poor oral hygiene. The most common movements were distalization and intrusion of teeth. More than a third of the cases involved complex movements in more than one plane of space. CONCLUSIONS: The success rate of skeletal anchorage system miniplates is high and predictable for a wide range of complex orthodontic movements.

Nonextraction treatment with temporary skeletal anchorage devices to correct a Class II Division 2 malocclusion with excessive gingival display.

The patient was a 22-year-old Japanese woman who complained of a gummy smile. She had several other orthodontic problems, including crowding of the maxillary anterior teeth, retroclination of the maxillary central incisors, excessive maxillary incisor display, a deep overbite, Class II dental relationships, a Class II profile, and a long face. Two options for the correction of these problems were proposed. The first option was to extract the maxillary first premolars to correct the Class II relationship and implant a miniscrew to correct the gingival display; the second option was to place 2 miniplates for distalization of the maxillary molars and a miniscrew to correct the gingival smile without premolar extractions. The patient chose the second option. After placing a preadjusted bracketed system, 2 miniplates were placed in the zygomatic buttresses bilaterally with monocortical screws, and 1 miniscrew was fixed between the root apices of the maxillary central incisors. Distalization and intrusion of the maxillary molars and intrusion of the maxillary incisors were simultaneously started with those temporary skeletal anchorage devices functioning as absolute orthodontic anchors. The total treatment period was approximately 22 months. Her orthodontic problems were corrected. According to the cephalometric evaluation, the entire maxillary dentition was significantly distalized, and her maxillary incisors were successfully intruded, with the mandible showing a slight counterclockwise rotation. Thanks to the temporary anchorage devices combined with miniplates and a miniscrew, we were able to predictably achieve her treatment goals without premolar extractions, orthognathic surgery, and the need for patient compliance.

Protraction of mandibular second and third molars into missing first molar spaces for a patient with an anterior open bite and anterior spacing.

In a young woman, aged 18 years 8 months, who had an anterior open bite and anterior spacing, the right and left mandibular first molar extraction spaces were closed by protraction of the second and third molars without reciprocal retraction of the incisors and the premolars. The amounts of protraction for the second molars were 12 mm on the right side and 11 mm on the left side. Two miniscrews were inserted into the mesiobuccal side of the edentulous spaces, and 2 more screws were inserted into the anterior sites after removing previous miniscrews. In addition, 4 miniscrews were inserted into the buccal and palatal sides between the first and second maxillary molars to intrude the maxillary posterior teeth, which had extruded into the missing mandibular spaces. Careful biomechanical consideration was used to prevent extrusion of the molars and worsening of the anterior open bite from protraction of the posterior teeth. Ultimately, the anterior open bite was corrected by both intrusion of the maxillary molars and extrusion of the maxillary anterior teeth. Excellent occlusion and correction of the anterior open bite were achieved without tipping, rotation of the posterior teeth, or other problems. The right mandibular third molar, which had been impacted at the beginning of treatment, erupted into the second molar space and functioned properly. At the 1-year follow-up examination, the patient had a slight anterior open bite, but closure of the first molar extraction spaces was well maintained.

One-phase vs 2-phase treatment for developing Class III malocclusion: a comparison of identical twins.

Despite the known influence of early treatment on the facial appearance of growing patients with skeletal Class III malocclusion, few comparative reports on the long-term effects of different treatment regimens (1-phase vs 2-phase treatment) have been published. Uncertainty remains regarding the effects of early intervention on jaw growth and its effectiveness and efficiency in the long term. In this case report, we compared the effects of early orthodontic intervention as the first phase of a 2-phase treatment vs 1-phase fixed appliance treatment in identical twins over a period of 11 years. Facial and dental changes were recorded, and cephalometric superimpositions were made at 4 time points. In spite of the different treatment approaches, both patients showed identical dentofacial characteristics in the retention phase. Through this case report, we intended to clarify the benefits of undergoing 1-phase treatment against 2-phase treatment protocols for treating growing skeletal Class III patients.

Beneficial effects of orthodontic treatment on quality of life in patients with malocclusion.

Patients with malocclusion, especially those in need of surgical correction, have lower health related quality of life (HRQOL) and higher anxiety. We investigated the changes of HRQOL and psychological status following jaw surgery in the patients with facial deformities. Thirty-one adult orthodontic patients admitted to Tohoku University Hospital and diagnosed as malocclusion requiring jaw surgery were recruited for the study. The severity of malocclusion was assessed by Severity Score (SS) which is based on their cephalometric radiographs. They were divided into three groups according to the severity of malocclusion, i.e. Low-SS, Moderate-SS and High-SS. The subjects also completed a generic HRQOL (entire body health) instrument, and three disease-specific oral HRQOL instruments. HRQOL and psychological status of the patients were assessed before (T1) and at debonding of multibracketed appliances after surgery (T2). SS in each group significantly decreased to normal occlusion level (SS = approximately 0-1). Oral function significantly improved from 11.8 +/- 5.4 to 5.9 +/- 4.3 in the Low-SS (p < 0.01), from 13.7 +/- 6.5 to 8.8 +/- 5.1 in the Moderate-SS (p < 0.05), and from 14.7 +/- 6.7 to 7.8 +/- 5.7 in the High-SS (p < 0.01). The patients after the surgical correction had improved disease-specific HRQOL and state anxiety irrespective of the severity before surgery, although the generic HRQOL, trait anxiety and depression were equal to that before the surgery. Furthermore, both postoperative anxiety and HRQOL were estimated by the preoperative anxiety and HRQOL. These results indicated that jaw surgery markedly improved the disease-specific HRQOL and psychological status in the present patients. We therefore suggest that assessments of the HRQOL and psychological status before treatment might predict the HRQOL and psychological status after the treatment to a certain extent.

Photoelastic stress analysis of mandibular molars moved distally with the skeletal anchorage system.

INTRODUCTION: The purpose of this study was to analyze photoelastically the stress distribution around teeth in the simulated distal movement of mandibular molars with the skeletal anchorage system. METHODS: Two types of the photoelastic mandibular dentition models were used, 1 before and 1 after distal movement of the second molar. The experiment was performed with 3 forms of traction--first-molar single traction, second-molar single traction, and simultaneous first- and second-molar traction. The direction of traction was set parallel to the occlusal plane and at an angle of 30 degrees downward to the occlusal plane. RESULTS: In the first-molar single traction model, extremely high stress was generated around the first molar with traction parallel to the occlusal plane. With the traction 30 degrees downward to the occlusal plane, all models showed the stress around the molars extended distally and downward. CONCLUSIONS: Simultaneous traction of the first and second molars might be preferable to the sequential traction of each molar to prevent the unfavorable distal tipping of the first molar. Regardless of whether simultaneous or sequential traction is used, the downward traction to the occlusal plane seems to induce intrusion of the molars as well as their distal movement.