Clinical analysis of skeletal malocclusion, axial inclination in patients with short root anomaly of the maxillary central incisors / 口腔疾病防治

Objective @#To investigate the prevalence and distribution of skeletal malocclusion and axial inclination of the maxillary central incisors in short root anomaly (SRA) patients in Kunming city, to provide some reference and guidance for SRA patients′ clinical diagnosis and treatment and prevention in SRA patients. @*Methods@#A total of 1 000 cases were randomly selected from the CBCT database of patients admitted to the author′s hospital from January 2011 to July 2019, and a retrospective analysis was performed. A total of 27 patients with SRA were diagnosed (SRA group).The control group, consisted of 100 randomly selected patients from non-SRA patients. According to the clinical data and cephalometric data, skeletal malocclusion was divided into three subgroups: Class I skeletal malocclusion, Class II skeletal malocclusion and Class Ⅲ skeletal malocclusion. Additionally, the axial inclination of the central incisors was divided into three subgroups: the lingual inclination group, labial inclination group and normal inclination group. The two groups each according to sex, skeletal malocclusion and types of axial inclination of the maxillary central incisors were discussed. @*Results @# The prevalence rate of SRA in the selected population was 2.7%, and the prevalence of SRA in females was 3.67% (21/572) , which was higher than that in males by 1.4% (6/428), and was significantly different between sexes (χ2=4.562, P=0.033). There was a significant difference between SRA patients and control group in terms of skeletal malocclusion (χ2=8.710, P=0.013). Class Ⅲ skeletal malocclusion was the main type of skeletal malocclusion in SRA. There was a significant difference between SRA patients and control group in terms of the axial inclination of the maxillary central incisors (χ2=16.75,P<0.001). Lingual inclination of the maxillary central incisors was the main type of axial inclination of the maxillary central incisors in SRA. @*Conclusion@#There is a certain correlation between class Ⅲ skeletal malocclusion and lingual inclination of the maxillary central incisors and SRA, and the root-crown ratio and root shape of these patients should be evaluated before orthodontics are implemented.

Radiographic assessment of clinical root-crown ratios of permanent teeth in a healthy Korean population

PURPOSE: The aim of this study was to determine the absolute value of the root/crown ratio (R/C ratio) using panoramic radiographs (PRGs) in a healthy Korean population. MATERIALS AND METHODS: In total, 99 patient radiographs (of 50 males and 49 females subjects; aged 16 to 24 years old) were examined, and 2,770 teeth were analyzed. Crown lengths and root lengths were measured with modified Lind's measurements using PACS tools by two examiners in two separate sessions two months apart. All data were analyzed using SPSS. The independent t-test was used to assess for gender differences, and the paired t-test was used to compare both arches with a significance level of P<.05. RESULTS: The mean R/C ratios varied from 1.29 to 1.89 (male: 1.28-1.84; females: 1.31-1.94). The highest R/C ratios were recorded for the mandibular canines (1.89), followed by the maxillary canines (1.79). The lowest R/C ratios were recorded for the maxillary second molars (1.31). In comparison with the maxillary teeth (1.29-1.78), the mandibular teeth yielded the higher R/C ratio (1.47-1.89), and this difference was significant in the females (P<.05). The difference between the genders was not statistically significant, except for the maxillary central incisors, mandibular canines and mandibular first premolars. CONCLUSION: These data may enhance the understanding of the clinical R/C ratio as a useful guideline for determining the status of teeth and the ethnic difference.

Root-crown ratios of permanent teeth in Malay patients attending HUSM Dental Clinic

The objectives of this study were to determine the normal mean value of the root-crown (R/C ratios) in Malay patients and their variations by gender and dental arch from orthopantomogram radiographs (OPGs). Two thousand nine hundred and twenty teeth with fully developed roots were measured from 112 OPGs. Subjects with history of maxillofacial trauma or orthodontic therapy were excluded. The mean age of the subjects was 19.1 (SD 2.08) years old for males while females 18.9 (SD 2.19) years old in the range from 15 to 22 years old. The intra-examiner reproducibility of the assessment method was good (Intraclass correlation coefficient 0.81). Results of this study showed that there was no significant difference between R/C ratios of males and females groups. However, the ratios of the antagonist teeth for both males and females were significantly greater in the mandible than in the maxilla (p<0.05 for right and left lateral incisors and right first premolars in male; p<0.001 for all other teeth). In both gender, the highest R/C ratio was mandibular second premolars and the lowest R/C ratio were maxillary central incisors. The rootcrown ratio could be used as a baseline data and reference to help in orthodontic diagnosis, treatment planning and prognosis as well as evaluation developmental root deficiency.