Katsuhiko Saitoh

Growth change of dental arch form in mixed dentition

To examine the potential dynamic influence of right and left imbalanced occlusal force on the cranial and facial bones, we prepared a 3-dimensional finite element model with a total of 126,534 nodes and 623,852 elements, which comprised 4 aspects including individual cranial sutures, facial bones, and cranial bones excluding mandibular bones, teeth, and periodontal ligament, according to cranial CT images taken from an adult dried skull. By using this model, we then performed 3-dimensional finite element analysis under the following 2 loading conditions: normal occlusion with right and left equality; and unilateral crossbite where the right side was normal but the left side showed crossbite, that is, where right and left imbalanced occlusal force was evident. In the normal occlusion model, a right and left symmetric stress distribution was observed around the key ridge surroundings as well as in the region covering the maxillary frontal aspect to the buccal bone. In the unilateral crossbite model as well, stress distribution was observed in both right-and left-sided key ridge surroundings as well as in the region toward the maxillary frontal aspect. When the right and left aspects were compared, however, the stress distribution was considerably biased, showing a different pattern of distribution. DOI: 10.1016/j.odw.2010.11.004

Relationship between molar occlusion and masticatory movement in lateral deviation of the mandible

Introduction: The relationship between molar occlusion and chewing patterns was examined in subjects with laterally deviated mandibles. Methods: Twenty‐three patients with mandibular deviation from the midline (4 mm or more) and skeletal Class I (0° ≤ANB ≤4°) were divided into 2 groups: normal bite and crossbite. The chewing pattern was classified as normal, reversed, or crossover. Results: The normal bite group had a normal chewing pattern on the affected side 100% of the time and a reversed chewing pattern on the affected and unaffected sides 0% and 7.2% of the time, respectively. Additionally, the normal bite group showed no evidence of a crossover chewing pattern and also had significantly less axial inclination of the mandibular teeth on the affected side compared with the crossbite group; lingual inclination was also evident. The crossbite group had a normal chewing pattern on the affected and unaffected sides 0% and 55.6% of the time, respectively, and reversed and crossover chewing patterns on the affected side 55.6% and 44.4% of the time, respectively. Conclusions: A normal chewing pattern tends to result in lingual axial inclination of the mandibular molars on the affected side, as well as a more consistent chewing pattern. HighlightsChewing was classified into 3 patterns: normal, reversed, and crossover.Subjects with normal bite had a normal chewing pattern.Compared with the crossbite group, the normal bite group had less axial inclination of mandibular teeth on the affected side.Subjects with normal bite had lingually inclined molars on the affected side.Normal chewing pattern may cause lingual inclination on the affected side and more consistent chewing patterns.

The long-term study about changes in hard and soft tissues and the position of the tongue at speech after postorthognathic surgery

The purpose of this study was to investigate factors that may influence the position of the tongue during speech by the use of acoustic analysis. The subjects were 21 patients diagnosed with mandibular prognathism who had undergone a sagittal split ramus osteotomy. The formants of / R / were analyzed before operation (BO), one month after operation (AO1m), and one year after operation (AO1y). To divided into 2 groups, F1/ F04 and F2/F04 of the control, and at the time of AO1y they were compared. These are the cases within the standard formants of AO1y (improved group), and cases over 1S.D. formants of AO1y (nonimproved group). The cephalometric analysis of each group was compared as well as the correlation between the formants and the cephalometric values. The results were as follows:

Morphological comparison of maxilloface, tongue posture, and pharyngeal airway before and after the mandibular setback surgery

In the present study, we reviewed the patients who were diagnosed as skeletal mandibular prognathism who underwent a sagittal split ramus osteotomy (SSRO) comparing the perioperative change of the tongue posture and the pharyngeal airway. Also, we considered it versus a postoperative change by SSRO about maxillofacial morphology of obstructive sleep apnea hypopnea syndrome (OSAS) and the pharyngeal airway. We reviewed 20 patients diagnosed as skeletal mandibular prognathism in our hospital. We compared the lateral cephalogram data of the patients one month before the operation (T1), one month after (T2), and one year after (T3), with 53 students belonging to our university setting as the normal group who displayed nothing abnormal with the maxillofacial, and 21 patients diagnosed as OSAS at the Tsukuba University Hospital.

Relationship between developmental change in mandibular dentition and maxillary dentition, and also in the palate

The purpose of this study was to investigate the features of dentofacial morphology and occlusion in patients who had experienced orthognathic surgery to treat mandibular protrusion. A questionnaire survey was performed in 2006 at the department of orthodontics in 29 dental schools and 2 private orthodontic practices. The subjects (n = 1,482) were patients who had been diagnosed as dentofacial deformities in the past 5 years. Those with mandibular protrusions (mandibular protrusion group n = 1,072) were divided into the following three categories: surgical, borderline, and orthodontic camouflage, and dentofacial features were examined by cephalograms and dental casts. Patients who had had a skeletal Class I malocclusion were served as a control group. The most common dentofacial deformity was a mandibular protrusion. Surgical cases had severe mandibular protrusion, lingually inclined mandibular incisors, molar Class III relationship, and mandibular deviation compared with borderline cases. In the multiple-logistic regression analysis comparing the mandibular protrusion group and control group, the following factors showed a large odds ratio, i.e. IMPA, U1 to FH, Wits appraisal, overjet, overbite, anteroposterior molar relationship, and mandibular dental midline deviation. OurresultssuggestedthatANB,Witsappraisal,andoverjetcould be useful indexes in diagnoses of mandibular protrusion. Moreover, not only these anteroposterior factors, but also vertical (overbite)andhorizontal (mandibulardeviation) factorsaffected the decision-making process for the application of orthognathic surgery. However, further investigations, including nonsurgical Class III cases, are required for presenting definite criteria of borderline cases to treat with orthognathic surgery.

Patients’ satisfaction survey after orthodontic treatment: Part 2 comparative study with objective treatment evaluation

month; eventually it had root fracture probably as a result of masticatory stress. The root-fractured tooth was immobilized with composite resin and orthodontic wire. The patient had a stable bite 6 years and 5 months after the fracture. A radiograph of the upper left-central incisor showed that the fractured site healed with interposition of bone and connective tissue. Also, the coronal fragment continued to erupt in concert with the growth of the alveolar process and helped to maintain the alveolar ridge of the same height and width as the adjacent teeth. These results indicated that ‘‘orthodontic traction of the inverted and impacted upper central incisor with a marked dilacerated root’’ was useful for maintaining the height and width of the alveolar ridge and would provide favorable conditions for replacing the retracted incisor with an implant or a bridge.

Clinical application of acoustic analysis in evaluation of tongue function

conditions. The results of adhesive paste comparisons with different consistencies showed that adhesives with lower filler levels produced significantly higher SBS than those with higher levels. No statistically significant differences in SBS were observed under the various bracket-pressing force or pressing-time conditions. Conclusion: Under the described test conditions, when a bracket with a plastic base was bonded using an adhesive paste containing an S-PRG filler, clinically acceptable SBS could be obtained by bonding with a relatively weak force, for a short period.

Prediction of dental crowding of permanent dentition from mixed dentition using personal longitudinal dental casts

To examine the potential dynamic influence of right and left imbalanced occlusal force on the cranial and facial bones, we prepared a 3-dimensional finite element model with a total of 126,534 nodes and 623,852 elements, which comprised 4 aspects including individual cranial sutures, facial bones, and cranial bones excluding mandibular bones, teeth, and periodontal ligament, according to cranial CT images taken from an adult dried skull. By using this model, we then performed 3-dimensional finite element analysis under the following 2 loading conditions: normal occlusion with right and left equality; and unilateral crossbite where the right side was normal but the left side showed crossbite, that is, where right and left imbalanced occlusal force was evident. In the normal occlusion model, a right and left symmetric stress distribution was observed around the key ridge surroundings as well as in the region covering the maxillary frontal aspect to the buccal bone. In the unilateral crossbite model as well, stress distribution was observed in both right-and left-sided key ridge surroundings as well as in the region toward the maxillary frontal aspect. When the right and left aspects were compared, however, the stress distribution was considerably biased, showing a different pattern of distribution. DOI: 10.1016/j.odw.2010.11.004