ABSTRACT
Objective@#Exploring the position and bone wall thickness characteristics of the maxillary central incisors in Southern Chinese adults to provide a clinical reference for the design of immediate maxillary central incisor implantation surgery.@*Methods@#The hospital ethics committee approved the study, and the patients provided informed consent. CBCT images of 990 adult patients (aged 20-79 years) from the Stomatology Hospital (January 2018 to December 2021) were categorized based on the dental arch form and age-sex groups. Sagittal CBCT images of the maxillary central incisors were used to measure the labial and palatal bone thickness wall at 4 mm the CEJ to apical, the middle of the root, and the angle between the tooth long axis and the long axis of the alveolar process, to compare the thickness of the labial and palatal bone walls in samples of male and female patients, and to explore the relationship between the angle between the tooth long axis and the alveolar process long axis in samples of male and female patients in different age groups (20-39 years; 40-59 years; 60-79 years).@*Results@#Significant differences were found in the labiopalatine side of the alveolar bone of the maxillary incisor root position. A total of 95.8% (948/990) of the maxillary incisors were positioned more buccally, 4.1% (41/990) were positioned more midway, and 0.1% (1/990) were positioned more palatally. The thicknesses of the bone wall at the CEJ of 4 mm below the palatal side, the middle of the root, and at the apex were greater (1.82 ± 0.56 mm, 3.20 ± 1.10 mm, and 7.70 ± 2.00 mm, respectively) than those at the labial side (1.21 ± 0.32 mm, 0.89 ± 0.35 mm, and 1.86 ± 0.82 mm, respectively), with statistical significance (P<0.05). Male bone wall thickness was generally greater than female bone wall thickness (P<0.05). The angle between the long axis of male teeth and the alveolar bone was 14.77° ± 5.66°, while that of female teeth was 12.80° ± 5.70°, with a statistically significant difference (P<0.05). The angle between the long axis of teeth and the alveolar bone in the 40-59-year-old group and the 60-79-year-old group was greater than that in the 20-39-year-old group, and the difference was statistically significant (P<0.05).@*Conclusion@#A total of 95.8% of adults in South China have maxillary central incisors with root deviation toward the labial bone cortex. The thickness of the labial bone wall is much thinner than that of the labial bone wall, which is the middle of the thickness of the root. In Southern Chinese adults, the angle between the upper central incisor and the long axis of the alveolar bone in males is greater than that in females, and the degree of the angle increases with age. It is recommended to pay attention to the thickness of the bone wall around the root and the angle between the teeth before immediate implantation surgery to choose a reasonable implantation plan.
ABSTRACT
<p><b>OBJECTIVE</b>This study aims to analyze the angulation of the maxillary anterior teeth relative to the alveolus to provide reference data for clinicians on the best conditions for implant placement in the esthetic zone.</p><p><b>METHODS</b>Numerous cone beam computed tomography (CBCT) images were reviewed and screened. A total of 150 maxillary images were selected by strict adherence to the defined inclusive criteria, with 75 images each from male and female patients (between the ages of 19 and 48 years at the time of CBCT scan). The maxillary anterior teeth were gathered into the following three groups for males and females: upper canines, upper lateral incisors, and upper central incisors. Then, the long axis of each qualified tooth and its corresponding alveolar process were drawn, and the angles formed by these structures were measured. The resultant data were analyzed by SPSS 19.0.</p><p><b>RESULTS</b>The long axis of the maxillary anterior teeth all inclined to the palatal side of the alveolar process. The internal angle (α) formed by the long axis of the maxillary central incisors and the long axis of the alveolar bone presented a mean value of 16.22° (range: 2.50°-28.80°) for male subjects and 15.20° (range: 2.20°-27.20°) for female subjects. The internal angle (α) of the maxillary lateral incisors exhibited a mean value of 17.50° (range: 3.80°-29.50°) for male subjects and 15.99° (range: 4.10°-33.30°) for female subjects. Finally, the internal angle (α) of the maxillary canines presented a mean value of 16.27° (range: 1.00°-31.50°) for male subjects and 15.01° (range: 3.50°-27.40°) for female subjects.</p><p><b>CONCLUSIONS</b>The long axis of the maxillary anterior teeth all inclined to the palatal side of the alveolar process. For implant placement, careful preoperative analysis and evaluation with CBCT may be beneficial for avoiding the risk factors and achieving a high probability of success in the esthetic region.</p>