Biomedical subjects
Publications and source records attributed to Jonathan L Gray.
We present a genome assembly from an individual male Gardnerycteris keenani (Chordata; Mammalia; Chiroptera; Phyllostomidae). The genome sequence is 2.2 Gb in span. The majority of the assembly is scaffolded into 32 chromosomal pseudomolecules, with the X and Y sex chromosomes assembled.
The purpose of this study was to compare clinical probing measurements with the histologic alveolar bone level in an established baboon model. Implant sites were prepared by removal of all premolars and first molars in 10 adult female baboons (Papio anubis), a total of 120 sites. The resulting edentulous ridges were allowed to heal for 6 weeks. One implant was placed in each site and allowed to heal, after which the implants were removed en bloc. The animals were not sacrificed. Clinical probing from the implant platform to the crest of the bone was performed at the buccal and lingual aspects of each implant at the time of placement and prior to section removal. All measurements were taken with a calibrated probe by a single examiner (ARV). Sections were cut in a buccolingual plane through the long axis of each implant. Histologic slides were digitized for data collection, and histologic measurements were taken at the buccal and lingual aspects from the implant platform to the crest of the bone. The results of the study showed that there were no significant differences between the clinical and histologic measurements. The authors concluded that clinical measurements around dental implants are as reliable as histologic measurements and that the tip of the probe extended to the alveolar bone every time the implant was probed in this model.
BACKGROUND: This study is a derivative of another study evaluating implant efficacy in baboons. In the previous study it was noted that some implants were placed near or into retained root tips. The purpose of this study was to evaluate the effect of the inadvertent placement of root form implants into or near retained root fragments. METHODS: The baboon has severe dilacerations at the apices of the roots, making extraction very difficult; 120 teeth were extracted from 10 baboons. After the sites had healed, root form implants were placed in each of the sites. Sites were either loaded at various time intervals or left unloaded. Block sections were removed and processed for histologic examination. RESULTS: When the specimens were analyzed, it was noted that several implants were placed through retained root fragments, while others were placed through the periodontal ligament of other root fragments. In a few cases, implants were close to, but not in contact with, either the root or the periodontal ligament. These implants functioned as well as the others in the study. Histologically, there was no inflammation at any site. In some sections, the roots were in intimate contact with the implants, while in others, there was a gap between the two. Where the implant was in contact with the periodontal ligament, there was no apparent fibrous encapsulization of the implant. In some areas, it appeared that a calcified material was deposited on the implants. It was not possible to determine whether this material was bone or cementum. CONCLUSION: Unintentional placement of dental implants into retained root fragments did not result in any inflammation and may have produced cementum or cementum-like matrix on the titanium surface adjacent to the periodontal ligament of the retained root tip.