上下無歯顎者におけるデンチャースペースと歯槽頂間線の相対的位置関係に関する臨床的研究

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In order to construct a stable lower denture, it is important to place posterior artificial teeth to fit functional movements of surrounding tissues. It is also desirable to place the artificial posterior teeth in complete denture causing as little leverage as possible. The purpose of this research was to determine the placement of artificial posterior teeth giving equal weight to both the "flange technique" and "the law of interalveolar crest line". The flange technique gives priority to muscle balance surrounding denture while the law of interalveolar crest line gives priority to occlusal balance. The three-dimensional shapes of denture space, alveolar crest line and Pound's line (cuspid retromolar pad guide line) as anatomical landmarks were measured. The relationship among parameters was examined. The results were as follows : 1. The averages of the mid-point of the denture space at the second premolar, the first molar and the second molar were 2.82mm, 2.57mm, 3.10mm on the buccal side of the interalveolar crest line respectively. 2. In only 2% of all cases in the molar region, the mid-point of the denture space lay on the intersection of the interalveolar crest line and the occlusal plane. 3. The mid-point of the denture space line was on the buccal side of the interalveolar crest line in 86% of all cases. 4. The averages of the inner angle of interalveolar crest line to the occlusal plane at the second premolar, the first molar and the second molar were 88.1° 85.6° and 80.3°, respectively. Therefore the interalveolar crest line became gentler towards the back of the posterior reduced ridge. 5. All the cases were divided into two groups at 80° (the inner angle of interalveolar crest line to the occlusal plane), and their mid-point denture space positions were compared. The below 80° inc. group was on the buccal side more than the over 80° group at the second premolar (significant p<0.05) and the first molar (not significant). On the other hand, the group over 80° tended to be on buccal side at the second molar (not significant). 6. The inside edge of the denture space was frequently within 1 mm of the inside Pound's line on either the buccal or lingual side. Consequently the inside Pound's line is considered a useful anatomical landmark for teeth arrangement. 7. The reduced alveolar ridge rate was measured at the second premolar, the first molar and the second molar. These data were divided into three groups : low (0 inc. ∿80%), middle (80 inc. ∿100%) and high (100 inc. ∿140%). The reduced rates in the three groups were compared with positions of their denture space positions. The denture space position tended to be strongly on the buccal side in the high group. The position of the inside edge of denture space at the second molar was closer to the interalveolar crest line in the high group. In order to ensure muscle balance surrounding denture and occlusal balance when placing the artificial posterior teeth in complete denture, it is suggested that artificial posterior teeth should be placed along the inside edge of the denture space. This is especially relevant, in cases with high reduced alveolar ridge ; that is, in difficult cases, the placement of the second molar should be paid excessive attention.
九州歯科学会の論文
1997-12-25

上下無歯顎者におけるデンチャースペースと歯槽頂間線の相対的位置関係に関する臨床的研究

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