The aim of this present study was to measure the occlusal angles of the buccal grooves in the maxillary deciduous and to reveal the difference of the angles between maxillary first deciduous molar and second deciduous molar. Dental casts of the deciduous dentition were obtained from children aged from three years under three years and one month, and caries free, hardly any attrition and with normal occlusion. The occlusal angles of the buccal grooves in the maxillary first deciduous molar and second deciduous molar were measured. The tangents were drawn at the disto-internal oblique plane of the mesiobuccal cusp and the mesio-internal oblique plane of the distobuccal cusp. The occlusal angle of the buccal groove was defined as the interior angle which intersected these tangents.
The results were as follows.
1. The mean occlusal angle of the buccal groove of the one third near the central pit was 128.40°at the maxillary first deciduous molar and was 107.43°at the maxillary second deciduous molar. The mean occlusal angle of the buccal groove of the one third near the buccal margin was 137.44°at the maxillary first deciduous molar and was 107.15° at the maxillary second deciduous molar.
2. The mean occlusal angles of the buccal groove of the maxillary first deciduous molar were larger than that of the maxillary second deciduous molar, and indicated a tendency for the angles to increase from the central pit toward the buccal margin.
3. According to research regarding whether the buccal groove was included in the outline form of cavity on the maxillary deciduous molars, the cases of first deciduous molars which included the buccal groove accounted for 32%, and those excluding the buccal groove accounted for 68%. On the other hand, the buccal groove was included in the outline form of cavity on the second deciduous molars in all the cases.