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The above scale can be used to determine accurately the position of bone within the cleft site. It can be used in the mixed dentition prior to eruption of the canine. It demonstrated moderate to substantial inter- and intraobserver reliability and offers several advantages, compared with other scales.

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Objectives: To propose a new scale for evaluating the position of the bone graft within the cleft and assess its inter- and intraobserver reliability. Design: Sixty-six patients (70 cleft sites) over a 14-year period were assessed, 90% of patients retrospectively and 10% prospectively. The radiographs were reviewed by two clinicians in controlled conditions twice, with 1 week between assessments. Both clinicians were blind to patient identity. Outcome measures: A new scale subdividing the position of the bone into one of six categories was used. The radiographs were also assessed using the Bergland scale. Results: Using the Bergland scale, 62.9% of the cleft sites were type I, 21.4% type II, 4.3% type III, and 5.7% type IV. It was not possible to assess 5.7% of the clefts with this scale because the canine was unerupted. Using the Chelsea alveolar bone graft scale, 58% were category A, 20% B, 7% C, 3% D, 3% E, and 9% F. Conclusions: The above scale can be used to determine accurately the position of bone within the cleft site. It can be used in the mixed dentition prior to eruption of the canine. It demonstrated moderate to substantial inter- and intraobserver reliability and offers several advantages, compared with other scales.

Since the first description of orbital blowout fractures, there has been much confusion as to their etiology. Two principal mechanisms have been proposed to explain their production, the buckling and the hydraulic mechanisms caused, respectively, by trauma to the orbital rim and the globe of the eye. The aim of this study was to evaluate both mechanisms qualitatively and quantitatively. Our protocol used intact cadavers, quantifiable intraocular pressure, variable and quantifiable force, and quantifiable bone strain distribution with strain gauge analysis. One orbit of each cadaver was used to simulate each of the two mechanisms, allowing direct comparison. Fractures produced by the buckling mechanism were limited to the anterior part of the orbital floor, with strain readings reaching up to 3756 microepsilon. Posteriorly, strain did not exceed 221 microepsilon. In contrast, hydraulic-type fractures were much larger, involving anterior and posterior parts of the floor as well as the medial wall of the orbit. Here, strain exceeded 3756 microepsilon in both parts of the floor. Furthermore, we have demonstrated that the average energy required to fracture the orbital floor by the buckling mechanism is 1.54 J, whereas an average energy of 1.22 J is needed to produce this fracture by the hydraulic mechanism. Our results suggest that efforts to establish one or another mechanism as the primary etiology are misplaced. Both mechanisms produce orbital blowout fractures, with different and specific characteristics. We believe this provides the basis for our reclassification of such fractures.

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