Incisal paths during habitual mouth opening and closing movements of children with anterior reverse bite in the early mixed dentition.

The purpose of this study was to investigate whether the pathways of habitual mouth opening and closing in children with anterior reverse bite in the early mixed dentition differed from those of children with normal occlusion. The two subject groups for this study were composed of ten children with anterior reverse bite (reverse bite group) and twelve children with normal occlusion (normal occlusion group), respectively. These movements were measured by an optoelectronic analyzing system with six degrees of freedom. Movements of the incisal point were projected on the sagittal plane to characterize the paths, and sagittal angles between the incisal path and the horizontal plane were calculated and compared. Opening and closing sagittal angles in the reverse bite group were almost equal over the entire pathway, indicating that the pathways of habitual mouth opening and closing were similar. In contrast, all opening and closing sagittal angles in the normal occlusion group were different, especially close to maximum intercuspation, indicating that their pathway of habitual mouth opening differed from their mouth closing pathway. In conclusion, children with anterior reverse bite in the early mixed dentition have different patterns of habitual mouth opening and closing movements than children with normal occlusion.

Occlusal contact area of mandibular teeth during lateral excursion.

PURPOSE: This study observed occlusal contacts and determined their areas on the mandibular teeth, especially the molars, during voluntary lateral excursions. MATERIALS AND METHODS: Occlusal contact areas were estimated with a measurement system combining 3-D tracking of mandibular movements with 3-D digitization of tooth shape. Sixteen women with sound permanent dentitions participated. RESULTS: At the intercuspal position, estimated occlusal contact areas of the first and second mandibular molars were on average 12.6 mm2 and 9.0 mm2, respectively. However, after 3.0 mm of lateral excursion, their areas were sharply reduced to 2.2 mm2 and 1.5 mm2 on the working side, and 0.4 mm2 and 1.1 mm2 on the nonworking side, respectively. CONCLUSION: These results suggest that the occlusal contact areas on working- and nonworking-side molars differ from each other as lateral excursion proceeds.

Association between palatal morphogenesis and Pax9 expression pattern in CL/Fr embryos with clefting during palatal development.

The CL/Fr mouse strain develops cleft lip and palate (CLP) spontaneously. In this study, Pax9 mRNA expression was investigated in the palatal shelves during palatal morphogenesis to assess the correlation between secondary palatal morphogenesis and Pax9 expression of CL/Fr embryos with spontaneous cleft lip and palate. The expression of Pax9 mRNA was characterised using whole mount in situ hybridisation with a digoxygenin-labelled probe. In the control strain of C57BL/6 and CL/Fr normal embryos, Pax9 was expressed in the palate, especially along the medial edge (ME), on embryonic day 13.5 (E13.5) and E14.5 when the palatal shelves grew vertically down the side of the tongue and subsequently elevated to a horizontal position, and was down regulated on E15.5 when the palatal shelves met and began fusing. In the cleft embryo, Pax9 was expressed in the ME region but was not down regulated on E15.5. Furthermore, whole mount in situ hybridisation was performed after organ culture, using CL/Fr-N and CL/Fr-BCL palatal shelves dissected and approximated by pairs on E13.5. This showed that Pax9 was still expressed in the ME region in separated palatal shelves of CL/Fr-N and CL/Fr-BCL embryos, while Pax9 expression was down regulated in paired palatal shelves. These expression patterns of Pax9 in normal and cleft embryos during palatal fusion indicate that Pax9 expression is altered in spontaneous cleft lip and palate, and concludes that there is a direct correlation between Pax9 expression and palatal fusion.

3.1 Scholarship and the university.

Universities now exist in an environment of increasing accountability for their academic performance, both in teaching and research. Dental schools are expected to meet the academic expectations of their parent university and, in addition, to contribute to the health-care needs of the community. Individual staff members must achieve collectively the performance targets required of their school and individually must develop skills and expertise in their academic and clinical activities to merit tenure and promotion. This discussion examines the issues which impact on current problems of recruitment and retention of academic staff in dental schools internationally. The essential issue is career development in a manner which maintains the values that will ensure the credibility of dentistry as a scientifically based discipline and profession, while balancing the achievable academic needs with the added demands of achieving specialist clinical skills. Central to this balance is recognition that scholarship, which provides the bridge between research and teaching, can be broadly defined and that different individuals can be scholarly in a range of ways. Increasingly, schools are recognizing the importance of providing structured opportunities and guidance for career development of younger staff and of the need for flexibility in their criteria for tenure and promotion, recognizing that a diversity of individual strengths and teamworking are necessary both for the collective performance of the institution and the morale and development of the individual.

Condylar motion in children with primary dentition during lateral excursion.

Normal development of primary and mixed dentition is indispensable for establishing a healthy mandibular function of the permanent dentition. Because condylar movements are crucial for mandibular function, extensive studies have been reported. However, most of these studies have dealt with mandibular functions in adults, and there is less known about children with primary dentition. The purpose of this study was to clarify the condylar movements during lateral excursions in children with primary dentition and compare these movements with those of adults from the viewpoint of functional development. With use of an optoelectronic recording system with six degrees of freedom, the lateral excursions of 24 children and 20 young women, with sound dentition, were recorded at 100 Hz. The results show that the balancing side condyle of the children had a significantly smaller vertical excursion and a significantly larger anteroposterior excursion than that of adults, indicating the shallower and more anteriorly directed movements of the entire mandible during lateral excursions in children with primary dentition.

Air pollution by concrete dust from the Great Hanshin Earthquake.

Air pollution in the areas affected by the Great Hanshin Earthquake (Hyogo, Japan) of 17 Jan. 1995 was quite serious. We performed three investigations of dust. In the first investigation, we measured the total suspended particulate (TSP) concentration in the greatly damaged areas, located around the Sannomiya Station where a few hundred thousand people walked by during the daytime of 3 February. The maximum concentration at five points reached 150 microg/m3. In the second investigation, eight samples, which were classified into three groups (concrete, mortar, and soil dusts) as sources, were analyzed elementally by X-ray fluorescence. The elements found in concrete dust (Ca and S) were similar to those found in mortar dust. These differed from those found in soil dust (Ti, Fe, and Zr). The elements found in soil dust were important from the viewpoint of heavy metal contamination. In the third investigation, the alkalinity of concrete dust was observed by dissolution. This solution was equivalent to pH 11 to 12 and electrical conductivity 20 to 30 microS/m. We suspect that the alkaline component in the dust from debris in all the devastated areas was approximately comparable with the alkaline solution by which the acid rain falling over the Hanshin district of Osaka Megalopolis in one year could be neutralized into water of pH 7.0.

Improvement in jaw motion following treatment of unilateral crossbite in a child with primary dentition: a case report.

This case report examines jaw motion during both habitual opening-closing and gum chewing in a young (3 years, 10 months) patient with unilateral crossbite at the primary dentition stage. Jaw motion was measured three times: 1. before treatment; 2. after active treatment; and 3. after retention. The abnormal habitual open-close pathway seen prior to treatment was improved after retention. Prior to treatment, movement of the affected-side condyle preceded movement of the non-affected-side condyle during opening. After retention, the movement of the condyles was better coordinated. The chopping type chewing pattern, with less lateral movement, before treatment changed to a more grinding type pattern on the affected side after activation. This study suggests that the prescribed treatment effectively improved both the patient's morphology and function. However, neither the open-close pathways nor the chewing patterns were completely normal after retention. The results in this case suggest that early treatment of functional unilateral crossbite can be effective.