PubMed · 3467068
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L I Linkow, E Wertman. 1986. Re-entry implants & their procedures.. https://pubmed.ncbi.nlm.nih.gov/3467068/
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Tooth eruption is an essential process for the survival of many different species and although the movement of teeth into function has been the subject of extensive research there is no consensus as to the mechanisms involved. Recent understanding of the mechanisms of cell activation and regulation has widened the scope for further research at the molecular level. This paper reviews the evidence for an eruptive force, its direction and source. The relationships between the eruptive force and molecular mechanisms of cell activation remain to be determined.
For quantitative evaluation of the different imaging quality of cephalograms and computed tomography in the region of the lower incisors, the macroscopic and histological findings of specimens were compared with the corresponding radiological findings. After removal of the soft tissue from 11 mandibular dentate segments, 15 artificial bone defects of different dimensions were produced in the region of the lower incisors. In comparison with the microscopic jaw measurements, the mean labiolingual diameter of the frontal alveolar process of the single incisors was overestimated in the cephalograms by 0.3 to 1.2 mm. Most of the anatomical-radiological correlations of the cephalometric measurements was insignificant. Individual metric assessment of the labiolingual bone width or of the facial/lingual cortical bone plates or the identification of the artificial defects of lower incisors in the cephalograms were generally not possible. In the CT-images the mean labiolingual diameter of the frontal alveolar process of the single incisors was overestimated by 0.1 to 0.5 mm, but the correlations were highly significant. The facial/lingual cortical bone plates of the lower incisors were evaluated and measured in the CT-scans. Thirteen of 15 artificial bone defects (80%) were identified in the CT-scans. CT-scanning is the only imaging technique offering three-dimensional quantitative evaluation of the labiolingual alveolar bone width and the facial/lingual cortical bone plates.
This study describes the precise determination of the extrusive force in the rat mandibular incisor measured for a relatively longer period of time under artificial respiration with halothane anaesthesia. Following restraint of the eruptive movement of the incisor for a period of 20 h, the pushing force increased gradually and was maintained as an extremely gentle slope toward the end of the experimental period. The maximum pushing forces were estimated to be 9.1 +/- 2.5 (SD) mN in impeded incisors and 9.8 +/- 2.3 mN in unimpeded incisors. When force was converted to pressure, values were 30 +/- 8 (SD)mmHg and 32 +/- 8 mmHg, respectively; the difference was not significant. The maximum pushing force decreased rapidly--almost in parallel--with the fall of systemic arterial blood pressure after death of the animals; the amounts of reduction were 7.2 +/- 1.8 mN (24 +/- 6 mmHg) in impeded incisors and 7.0 +/- 2.0 mN (23 +/- 7 mmHg) in unimpeded incisors. Residual pushing forces were 1.7 +/- 1.0 mN (5.6 +/- 3.3 mmHg) in impeded incisors and 2.5 +/- 0.6 mN (8.2 +/- 2.0 mmHg) in unimpeded incisors; the difference was significant (P < 0.05). These results suggest that, under these experimental conditions, the pushing force of the rat incisor originates primarily from localized blood pressure within the incisor socket and, in part, from tissue growth.