Mixed dentition analysis for Hong Kong Chinese.

Using simple linear regression analyses, prediction equations for the combined mesiodistal crown diameters of canines and premolars based on lower incisor size were generated from 97 Hong Kong Chinese (51 males and 46 females, average age 12.31 years) out of a sample of 112. The mesiodistal crown diameters of the permanent teeth were measured using calipers and recorded to the nearest 0.01 mm. Significant sex differences were found for the combined diameters of the canine-premolar segments. The coefficients of correlation between combined diameters of canines and premolars and lower incisors ranged from 0.65 to 0.79. Significant sex differences of the regression equations were found and thus four simple linear regression equations were generated. Coefficients for the slope ranged from 0.58 to 0.66, and coefficients for the intercept ranged from 6.66 to 8.82. The R2 values, standard errors of estimate, and absolute mean errors revealed that prediction models for females were less precise than those for males. Probability tables were constructed from the results of the present study. The prediction equations were found to differ from those of Tanaka and Johnston. Accuracy in the mixed dentition analysis for southern Chinese would be improved by applying the prediction equations or probability tables generated from the present study.

A comparative study of sagittal correction with the Herbst appliance in two different ethnic groups.

The dentofacial morphology of Chinese is different from Caucasians. The purpose of this investigation was to assess the skeletal and dental changes contributing to the sagittal correction in group of consecutive Chinese children who were treated with the Herbst appliance. A comparison was made between 14 Chinese and 14 Swedish subjects who all had Herbst appliance treatment. All subjects were corrected from the Class II division 1 malocclusion to an overcorrected Class I or Class III dental relationship within a 6-8 month period. Lateral cephalograms taken before and immediately after the Herbst treatment were analysed. In general, the skeletal and dental changes during treatment were comparable between both ethnic groups. However, individual variations within the two groups were wide. It can be concluded that the Herbst appliance was equally successful in Southern Chinese children and similar treatment changes as those achieved in Swedish children could be found.

Correlation of sexual maturation with skeletal age of southern Chinese girls.

The correlation of skeletal maturation with the chronological ages of the onset of four secondary sexual characteristics (menarche, appearance of pubic hair and axillary hair, and breast development) was studied in a group of 117 Southern Chinese girls aged between 11 years, 9 months and 12 years, 3 months, who were born and brought up in Hong Kong. The skeletal maturation was assessed from left hand and wrist radiographs by the Greulich and Pyle Atlas Method (1959). The early maturers in sexual maturation were significantly more advanced in skeletal maturity with p < 0.001.

Soft tissue profile changes of reverse headgear treatment in Chinese boys with complete unilateral cleft lip and palate.

Midface retrusion in cleft lip and palate patients often results in personal, social, and psychological problems, along with the functional difficulty. Hence, soft tissue profile improvement in early childhood is of obvious importance. The purpose of this study was to investigate the soft tissue changes that occur during reverse headgear treatment in a homogeneous sample of Chinese boys born with unilateral complete cleft lip and palate. Boys with a similar congenital deformity and presenting similar skeletal morphology and maturity status were included for comparison. After 7.8 months of reverse headgear treatment, the soft tissue profile improved significantly as the concave tendency associated with maxillary deficiency decreased. The sagittal maxillomandibular lip relationship and the Holdaway angle increased significantly by 4.25 and 3.94 degrees, respectively.

Mesiodistal crown diameters of the primary and permanent teeth in southern Chinese--a longitudinal study.

The mesiodistal crown diameters of the primary and permanent teeth were measured on serial casts of 112 Hong Kong Southern Chinese (61 males and 51 females) taken at 5.68 and 12.31 years of age. None of the teeth showed significant sex difference in bilateral asymmetry, and significant bilateral asymmetry was found only for the upper primary second molars. The asymmetries were small and the sizes of the antimeres were averaged. Posterior teeth were generally less variable than anterior teeth in both dentitions in Chinese, which is contrary to other reports, but the anterior tooth of each morphological class was, in general, less variable than the posterior member. Male teeth were larger than those of females except for the lower central and lateral incisors in both dentitions, but the difference was not statistically significant. None of the primary teeth nor three of the permanent teeth were found to have significant sex differences in size. Percentage sexual dimorphism ranged from 0.06 to 1.97 per cent for the primary teeth and from 0.36 to 5.27 per cent for the permanent teeth. In the primary dentition, molars were the most dimorphic teeth in both arches, while upper incisors and lower canine were the least dimorphic teeth in their own arch. Among the permanent teeth, the canines were the most dimorphic and the incisors were among the least dimorphic teeth in both arches. Tooth sizes in both dentitions were, in general, larger than those of the Caucasians, comparable with Northern Chinese, but smaller than those of Australian Aboriginals.

Skeletal maturation of the hand and wrist and its correlation with dental development.

The maturation status of each hand and wrist bone age of 117 12-year-old Southern Chinese girls was studied using the Greulich and Pyle Atlas (1959) Method. The bone ages were found to range from 12.14 years (scaphoid) to 12.80 years (middle phalanx V). The mean and standard deviation of the skeletal age of the hand and wrist region were 12.57 years and 1.11 years, respectively. Skeletal maturation of 102 of these Southern Chinese girls was correlated to the developmental status of their permanent dentition. A statistically significant difference with p < 0.01 was found between the skeletally above-average and skeletally below-average girls. Contrary to previous studies, the skeletally below-average group had on average 1.1 more erupted permanent teeth than the skeletally advanced group. In addition, there did not seem to be any close relation between apical closure of the permanent mandibular canine and bone age of the adductor sesamoid.

Effects of reverse headgear treatment on sagittal correction in girls born with unilateral complete cleft lip and cleft palate--skeletal and dental changes.

Patients with cleft lip and cleft palate often develop maxillary retrognathism. This is due to the combined effects of the congenital deformity and surgical repairs. Early protraction of the maxilla with extraoral forces helps to achieve more balanced skeletal harmony and favorable occlusion for future growth to occur. The purpose of the present study is to investigate the proportion of the skeletal and dental changes contributing to the improvement in a group of Southern Chinese girls born with unilateral complete cleft lip and cleft palate treated by the reverse headgear. This study only focused on treating a homogenous sample group, i.e., only girls with unilateral complete cleft lip and cleft palate. This design was deliberate so as to avoid having boys and girls with various types of cleft all pooled together for analyses as seen in most of the previous reports. In addition, comparison was made with girls matched in having a similar deformity, presenting a similar skeletal structure and maturity status to reveal the genuine treatment effect. The 9.7 months of reverse headgear treatment improved the sagittal jaw relationship (p < 0.01) and overjet (p < 0.01), which was effected by about two-thirds skeletal and one-third dental changes.

Relations between the mesiodistal crown diameters of the primary and permanent teeth of Hong Kong Chinese.

Relations between these diameters were studied on serial dental casts of 112 Hong Kong Chinese (61 males, 51 females) taken at mean ages of 5.68 and 12.31 yr. Size relations were studied in terms of correlation coefficient, difference, and ratio between corresponding pairs of individual teeth and corresponding groups of teeth in both dentitions. The coefficients of correlation were low to moderate (0.2-0.8), with those between groups of teeth consistently higher. As for size differences, incisors and canines were larger in the permanent dentition in both arches by 1.2-2.0 mm. Premolars were smaller than their primary predecessors except for the upper first premolar. When the absolute values of the differences were ranked, the second premolar-second primary molar differences were the greatest (2.0-2.8 mm) while those between the first premolar-first primary molar were the smallest (0.3-0.7 mm). When tooth groups were assessed, the permanent teeth were larger than their predecessors in the anterior segments but smaller in the posterior segments. The leeway space was larger in the mandibular arch (2.2 mm) than in the maxillary arch (0.3 mm). When diameters of five teeth on one side of the arch were combined, the permanent exceeded the primary by 3.5 mm in the upper arch but only 0.5 mm in the lower. The ratios between the permanent and primary tooth sizes showed the same trend as the differences.

Sagittal skeletal and dental changes of reverse headgear treatment in Chinese boys with complete unilateral cleft lip and palate.

Cleft lip and palate patients often develop maxillary retrusion after cleft repair. Maxillary protraction treatment during early childhood helps to achieve more favorable occlusion with positive overjet and overbite and allows a more normal growth pattern to occur. The purpose of this study was to investigate the skeletal and dental changes during reverse headgear treatment in a homogeneous group, i.e., Chinese boys born with unilateral complete cleft lip and palate. The results showed that after 7.8 months of reverse headgear wear, normalization of the sagittal maxillomandibular relationship (ANB angle) was achieved. Significant skeletal changes included anterior position of the maxilla and posterior position of the mandible. Dental changes within the respective skeletal units were not significant except for the mandibular molar.

Alternative donor site for alveolar bone grafting in adults with cleft lip and palate.

Grafting of the alveolar ridge with autogenous bone is an integral stage of contemporary management of complete cleft lip and palate cases. Alveolar bone grafting restores continuity of the dental arch, closes oronasal fistulae, supports the alar base, and facilitates spontaneous eruption of permanent teeth adjacent to the cleft. However, timing of the graft and the selection of materials have been topics of much debate in the literature. This article discusses an alternative donor site in cases where rehabilitation has passed the recommended time. Harvesting bone from the third molar regions allows not only the removal of impacted third molars during the same surgical procedure, but also eliminates the morbidity associated with additional surgical sites such as the ilium or mandibular symphysis. This report should not be interpreted as a recommendation for the use of this alternative site in cases where grafting is carried out within the optimal time period, which is usually in the mixed dentition stage. However, when grafting is necessary in young adults suffering from complete cleft lip and palate, the third molar region may provide another acceptable donor site.

Correlation of sexual maturation with stature and body weight & dental maturation in southern Chinese girls.

Correlation of stature and body weight and the eruption of permanent teeth with four sexual maturity criteria (menarche, pubic hair, axillary hair and breast development) was studied in 102 Southern Chinese girls aged between 11 years, 9 months and 12 years, 3 months and born and brought up in Hong Kong. With respect to all four selected criteria, the early sexual maturers were significantly taller and heavier and had more erupted permanent teeth with p values ranging from < 0.01 to < 0.001 levels than the late maturers.

Correlation of orthodontic treatment demand with treatment need assessed using two indices.

The orthodontic treatment need of 105 first year university students (51 males and 54 females, mean age 19.75 years) at the University of Hong Kong was assessed using the Occlusal Index (OI) and the Index of Orthodontic Treatment Need (IOTN). The results were compared with the subjects' orthodontic treatment demand derived from a questionnaire. The OI assessment correlated better with the individuals' own perceptions of appearance than did the IOTN, and the treatment need indicated by the OI also correlated better with the individuals' actual treatment demands.

A comparative study using the Occlusal Index and the Index of Orthodontic Treatment Need.

Assessment of malocclusion is important for documentation of the prevalence and severity of malocclusion in population groups. Such information is needed in Hong Kong where less than 25 qualified orthodontists serve a population of about 6 million citizens. The objective of the present study was to compare the Occlusal Index (OI) and the Index of Orthodontic Treatment Need (IOTN) when used to assess orthodontic treatment needs in a local population. Only a weak association (Spearman's correlation coefficient = 0.31) was found between the two indices. The shortcomings of both indices are discussed. Neither OI nor the IOTN is perfect, but using the IOTN is less time consuming, making the study of a large population group more practical.

Secular trends of stature and weight of Chinese girls.

Stature and weight were studied in 123 12-year-old Southern Chinese girls born and brought up in Hong Kong. The mean stature was 147.22 centimetres with a standard deviation of 6.65 centimetres. The mean body weight was 37.11 kilograms with the standard deviation being 7.39 kilograms. Secular trend of increased body size was demonstrated. The increase was more marked in the lower percentile groups.

Secular trend of menarcheal age in southern Chinese girls.

Southern Chinese girls aged 11 years and 9 months to 12 years and 3 months in Hong Kong have a mean menarcheal age of 11.50 years (standard deviation of 0.47) using the recollection method. Highly significant differences are found when compared to the 12-year-old girls in Hong Kong studied in the past decades. Therefore, a secular trend of earlier menarcheal age is demonstrated.

Prevalence and severity of malocclusion in children with cleft lip and/or palate in Hong Kong.

The prevalence and severity of malocclusion among children with cleft lip and palate in Hong Kong has never been assessed or documented. A group of 20 children in the primary or early mixed dentition stages, with clefts of the lip and/or palate were assessed using the Occlusal Index. Results of this preliminary study showed that 92.3 percent of the male and 71.5 percent of the female subjects had severe malocclusion, which implied that comprehensive orthodontic treatment at a later stage would be needed. More than half (69.2% of the male, and 57.1% of the female subjects) had syndrome F, defined as mesial molar relationship, overjet, overbite, posterior crossbite, midline diastema, and midline deviation (Summers, 1966). Therefore malocclusion problems were shown to manifest early in patients with cleft lip and/or palate, and further that it is possible to assess malocclusion prevalence and severity in early stages of dental development.

Radiographic features of the bones of the hand and wrist in achondroplasia: report of case.

Achondroplasia is a well-established and documented medical condition. Most of the diagnostic features are discernible from a clinical examination, which are complemented by radiographic findings of the bones of the skeleton. The findings from the hand-and-wrist radiograph of an affected Southern Chinese male infant, age thirty-nine-months, are reported. The findings from this case indicated an infrequently reported abnormality in the development of the hand in achondroplasia.

Correlation of skeletal maturation with stature and body weight of southern Chinese girls in Hong Kong.

Correlations of skeletal maturation with stature and body weight were studied in one hundred and seventeen Southern Chinese girls aged eleven years nine months and twelve years three months born and brought up in Hong Kong. The skeletal maturation was assessed from the left hand and wrist radiographs by the Greulich and Pyle Atlas Method. The early maturers in skeletal development were significant taller and heavier than the late maturers with p less than 0.001.