ABSTRACT
STATEMENT OF PROBLEM: Consideration of the thickness of alveolar bone on both the palatal and labial sides and the inclination angle of teeth is important for immediate implant placement in the maxillary anterior region. However, comprehensive research exploring how sex and age influence the thickness of bone and tooth angle in the maxillary anterior region is lacking. PURPOSE: The purpose of this clinical study was to investigate the effect of sex and age on the thickness of labial and palatal bone and on the tooth inclination angle of maxillary central and lateral incisors using cone beam computed tomography (CBCT) images in an Asian population. MATERIAL AND METHODS: The labial and palatal bone thickness and the inclination angle of maxillary central and lateral incisors were measured from the CBCT images of 149 participants aged between 20 and 65 years. The correlation between the angles of the maxillary central and lateral incisors and sex and age on the tooth angles and thicknesses of labial and palatal bone was determined statistically. RESULTS: A high correlation (R=0.73) was found between the angle of maxillary central and lateral incisors. Men had higher angles of the maxillary central and lateral incisors and thicker palatal bone at the middle and root of the teeth compared with women. In both sexes, the angle and palatal bone thickness of maxillary central incisors were significantly higher than those of maxillary lateral incisors. The angle of both maxillary central and lateral incisors decreased gradually with age, with a difference in angle of over 10 degrees. CONCLUSIONS: The study revealed that women exhibited relatively thinner palatal bone compared with men. Additionally, participants aged between 40 and 65 years exhibited significantly thicker palatal bone compared with younger age groups, potentially providing a larger site for implant placement. Furthermore, tooth angle gradually decreases with age in the maxillary anterior region.
ABSTRACT
PURPOSE: Finite element analysis and an in vitro experiment were employed to investigate the loading effects of angled abutments, comparing various customized angled abutments derived from the average angle of incisors in patients with a commercial 15°∆ angled abutment, on both the implant and surrounding bone. METHODS: Four customized angled abutment models (21.9°∆, 24.15°∆, 20.22°∆, 33°∆) were developed using cone-beam computed tomography (CBCT) images of incisor inclination from various age groups of patients. 3D maxillary bone models were created from CBCT images of four individual patients. Finite element analysis and in-vitro strain gauge experiments were conducted, applying 100N or 50N of axial or oblique force, to assess the differences in stress/strain between the customized and the commercial 15°∆ angled abutments in both the implants and surrounding bone. RESULTS: Under axial loading, the stress values in the dental implant and surrounding bone were elevated due to the relatively higher angles of the customized angled abutments (21.9°∆, 24.15°∆, 20.22°∆, 33°∆) when compared to the commercial 15°∆ angled abutment; however, under oblique loading the commercial 15°∆angled abutment exhibited higher stress values in both the implant and surrounding bone. For in vitro experiment, there is no statically difference in bone strain between the customized (21.9°∆) and the commercial 15°∆ angled abutments in axial loading. Nevertheless, in oblique loading using a commercial 15°∆ angled abutment induced the higher bone strains. CONCLUSION: Customized angled abutments offer lower stress/strain under oblique loads but higher stress/strain under axial loads compared to commercial ones. Therefore, in the design and application of angled abutments, careful consideration of the occlusal load direction is paramount for achieving biomechanical success of dental implant.
