The Human Bone Collection of the Faculty of Dentistry at the University of Hong Kong: History and description of cranial and postcranial skeletal remains.

OBJECTIVES: The present work describes the status and contents of The Human Bone Collection of the Faculty of Dentistry at the University of Hong Kong. MATERIALS AND METHODS: The Collection originates from the 1980s and became officially established in 2017 for teaching and research purposes. Most of the Collection consists of unclaimed human remains of southern Chinese individuals exhumed from local cemeteries and donated to the Faculty in the last few decades. The demographic information was provided largely from burial records and forensic estimations. Since 2016, the Collection has undergone a process of reorganization into cranial and postcranial remains, followed by preservation procedures that included cleaning and classification. RESULTS: The Collection currently consists of remains belonging to about 368 individuals (243 males, 54 females, 71 unknown), with ages ranging from 0.8 to 90 years (mean 57.4 years). It comprises cranial remains belonging to 260 individuals (169 males, 39 females, 52 unknown), and postcranial remains belonging to 248 individuals (180 males, 42 females, 26 unknown). The preservation status ranges from poor to good, with the cranial remains better preserved than the postcranial elements. For a large number of individuals, ear ossicles, soil samples, and other materials are also available. DISCUSSION: The Collection is accessible to local and international institutions for teaching and research.

Accuracy of radiographic measurements for implant planning using cone-beam and helical computer tomography.

AIM: The aim of the present study was to compare the accuracy of radiographic measurements for dental implants planning using cone-beam computed tomography (CBCT) and helical computed tomography (HCT). METHODS: Six pig ribs were wrapped by putty impression material, with radiographic markers placed. Two CBCT and an HCT were taken following the standard protocols. Twenty-five locations were selected, with vertical and horizontal dimensions measured using the default software, as well as on the processed HCT films by a digital caliper. The actual dimensions of the ribs measured by the digital caliper served as the control. Differences between radiographic dimensions and the actual dimensions were tested by two-way analysis of variance. RESULTS: No differences were found between measurements made by CBCT and HCT images using the default software (P > 0.05). However, both measurements were statistically-significantly lower than the control (P < 0.001), and the mean difference was 0.3 mm. Measurements made on HCT films were statistically-significantly greater than the control (P < 0.001), and the mean difference was 0.5 mm. CONCLUSION: The accuracy of CBCT and HCT are similar, and both are reliable tools for implant planning. It is preferable to perform the planning using default software, rather than making direct measurements on films.