The aim of this study was to determine the proximity of the nasopalatine canal (NPC) to the maxillary central incisor root (MCIR). The study included 120 cone beam computed tomography scans obtained from the Center for Implant Dentistry, Loma Linda University, between June 2006 and September 2009. They were equally distributed into six groups: (1) 21- to 40-year-old men, (2) 21- to 40-year-old women, (3) 41- to 60-year-old men, (4) 41- to 60-year-old women, (5) 61- to 80-year-old men, and (6) 61- to 80-year-old women. The closest distances between the NPC and the MCIR (NPC-to-MCIR) were measured at the midroot (bisecting palatal cementoenamel junction to root apex) and the apex levels. Differences between the groups were analyzed using a t test and 1-way analysis of variance at a significance level of α = .05. The overall mean NPC-to-MCIR distances at the midroot and apex levels were 3.05 ± 1.64 and 5.22 ± 1.56 mm, respectively. The modes of the NPC-to-MCIR distances at the midroot and apex levels were in the range of 1.01-2.00 mm and 4.01-5.00 mm, respectively. The mean NPC-to-MCIR distance was significantly greater in men than in women at the midroot level (P < .05) but not at the apex level (P > .05). The mean NPC-to-MCIR distance was significantly shorter for the youngest age group than the other two age groups at the midroot level (P < .05). However, at the apex level, the youngest age group had a significantly shorter distance compared with the oldest age group (P < .05) but not the middle age group (P > .05). The results of this study suggest that, to avoid NPC penetration, more care must be exercised during immediate implant placement at the midroot level of a maxillary central incisor in women and younger patients because of the root proximity to the NPC. Tapered implants may also be beneficial in such situations.

The purpose of this study is to use cone-beam computerized tomography (CBCT) scans with oblique-transverse reconstruction modality to measure and compare the anterior loop length (AnLL) of the mental nerve between gender and age groups and to compare the difference between the right and left sides. Sixty-one female and 61 male CBCT scans were randomly selected for each age group: 21-40, 41-60, and 61-80 years. Both right- and left-side AnLLs were measured in each subject using i-CATVision software to measure AnLLs on the oblique transverse plane using multiplanar reconstruction. The anterior loop was identified in 85.2% of cases, with the mean AnLL of the 366 subjects (732 hemimandibles) being 1.46 ± 1.25 mm with no statistically significant difference between right and left sides or between different gender groups. However, the mean AnLL in the 21-40 year group (1.89 ± 1.35 mm) was larger than the AnLL in the 41-60 year group (1.35 ± 1.19 mm) and the 61-80 year group (1.13 ± 1.08 mm). In conclusion, when placing implants in close proximity to mental foramina, caution is recommended to avoid injury to the inferior alveolar nerve. No fixed distance anteriorly from the mental foramen should be considered safe. Using CBCT scans with the oblique-transverse method to accurately identify and measure the AnLL is of utmost importance in avoiding and protecting its integrity.

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