RESUMEN
<p><b>OBJECTIVE</b>This study aimed at investigating and measuring the positional relationship between the long axis of the mandibular anterior teeth and the alveolar bone using cone beam computed tomography (CBCT) to provide reference data for implant treatment.</p><p><b>METHODS</b>From the CBCT image database, 150 cases of radiographic data were selected according to the inclusion criteria and then were divided into six groups: males' mandibular central incisors, males' mandibular lateral incisors, males' mandibular canines, females' mandibular central incisors, females' mandibular lateral incisors, and females' mandibular canines. The angle (β) formed by the long axis of the mandibular anterior teeth and the corresponding alveolar bone was measured and recorded. Based on the long axis of alveolar bone, if the teeth incline to the lingual side, the value of the angle (β) was positive; otherwise, the value was negative. The resultant data were analyzed by SPSS 19.0.</p><p><b>RESULTS</b>The β of the mandibular central incisors presented a mean value of 4.77° (range: -8.17°-16.10°) for male subjects and 5.38° (range: -5.63°-12.93°) for female subjects. The β of the mandibular lateral incisors exhibited a mean value of 6.12° (range: -2.87°- 17.57°) for male subjects and 5.81° (range: -7.70°-15.70°) for female subjects. Finally, the β of the mandibular canines presented a mean value of 5.01° (range: -8.13°-17.67°) for male subjects and 6.21° (range: -7.70°-17.87°) for female subjects. The percentages of the β between -10° and 10° of males' mandibular incisors, mandibular lateral incisors, and mandibular canines were 87.34%, 80.67%, and 88.00%, respectively and those of females were 90.67%, 82.66%, and 82.66%, respectively. Whether male or female, the percentages of the β between -10° and 10° of the mandibular anterior teeth were more than 80%. The β that inclined to the lingual was not more than 20° and to the labial did not exceed 10°.</p><p><b>CONCLUSIONS</b>The long axis of the mandibular anterior teeth was almost consistent with the long axis of the alveolar bone. Therefore, the positional relationship could be referred to make reasonable implants treatment plan.</p>
RESUMEN
<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>