Craniofacial and alveolar bone changes in young adults : a 4-year longitudinal study

Abstract

The purpose of this study is to radiographically evaluate changes of the young adult craniofacial and alveolar bone over a 4 year period. Three radiographic examinations were performed longitudinally, the first (T0) was conducted at the start of the study, the second (T1) was performed 2 years thereafter, and the third (T2) was examined at the end of the study period. The radiographic examinations included lateral cephalograms, maxillary and mandiblular anterior periapical radiographs, and bilateral posterior bitewing radiographs. The radiographs of 82 adults were obtained and measured. The following results were observed: 1. The most significant skeletal change in the craniofacial region was associated with the lengths of anterior and posterior facial height (p<0.001). In maxilla, both males and females showed forward movement (p<0.05), whereas mandible showed antero-superior rotation as the length of mandibular body grew in males and postero-inferior rotation with the growth of mandibular body in females (p<0.05). 2. Upper incisor angles decreased in both males and females (p<0.05). The upper and lower incisors and molars all showed an increase of vertical distance from the reference planes in both males and females (p<0.001). 3. In regards to soft tissue changes, it turned out that the thickness of the upper and lower lips decreased (p<0.05) and the apex of nose move anteriorly in both male and female (p<0.01). 4. The average overall change of the alveolar bone was 0.27 mm and the yearly change was 0.07 mm over the 4 years period. Also, the degree of alveolar bone resorption at the starting point of the observation did not have any correlation with the alveolar bone change. 5. Between the skeletal change and the alveolar bony change, no specific correlation was examined in the first 2 years, however a weak correlation was found in some measurements during the subsequent 2 years (p<0.05). The results of this study indicate that there were statistically significant changes in the skeletal, dental, soft tissue and physiologic changes in alveolar bone in young adults.