RESUMEN
Objective:To investigate the labial(buccal)bone thickness at alveolar crest zone and alveolar crest height of the maxil-lary anterior teeth and premolars of young adults with normal occlusion.Methods:The alveolar bone of the anterior teeth and premo-lars of 67 eligible Han national young volunteers was scanned by CBCT.Then the facial bone thickness and the distance between the facial alveolar crest and Cemento-enamel Junction(CEJ)of the anterior teeth and premolars were measured and analyzed after recon-struction.Results:The distance between labial (buccal)crest and labial (buccal)CEJ of the maxillary first premolars was the lar-gest(P <0.05);there was a negative correlation between the labial(buccal)crest height and the facial alveolar bone thickness at 2 mm from CEJ toward root derection[(P <0.05),0.6 <|r|<0.8].Conclusion:The labial (buccal)crest of the first premolars was higher than that of other teeth in maxillary aesthetic zone.At alveolar crest zone,when the labial (buccal)bone was thinner,the dis-tance between labial (buccal)crest and labial (buccal)CEJ was larger,and the implant aesthetic risk is higher.
RESUMEN
Alveolar crest is the section of interproximal alveolar bone which includes the free edge of the alveolar process. An increase of the normal forces within limits of tolerance leads to deposition of new bone. If forces are beyond the limits of tolerance, resorption of bone will result whether the force produces pressure or tension. This study was designed to evaluate changes of alveolar bone levels in mesial and distal surface of the left, right first molar, by using pre-treatment, post-treatment panorama films. Two hundreds sixteen subjects were divided into adolescent group of 104 subjects and adult group of 112 subjects, to which orthodontic treatment with a bicuspid extraction (adolescent group-50 subjects, adult group-50 subjects) or without a nonextraction (adolescent group-54 subjects, adult group-62 subjects) was applied by fixed appliances. Pre- and post-treatment panorama films were traced, and alveolar crest height was measured. Amounts of changes in alveolar crest height by treatment were calculated and compared in terms of side of tooth, extraction, age. The results were as follows; 1. When pre-treatment alveolar crest bone levels were compared, levels of adult group were significantly lower than those of adolescent group. 2. Post-treatment alveolar crest bone levels were significantly lower than pre-treatment levels. 3. When changes of alveolar crest height were compared, between adolescent and adult group were not significantly. 4. When changes of alveolar crest height were compared, significantly larger changes were noticed in extraction than nonextraction cases. 5. When changes of alveolar crest height were compared, significantly larger changes were noticed in maxilla than mandible. 6. When mesio-distally compared, significantly larger changes were observed in the distal than mesial sides of adult group.