Reconstruction of occlusal plane orientation using Camper’s line as reference

1. B A B Reconstruction of occlusal plane orientation using Camper’s line as reference Čelebić Asja, Petričević Nikola, Guberina Marko, Baučić Ivo, Stipetić Jasmina School of dental Medicine, University of Zagreb, Croatia Introduction: The position of occlusal plane should be as close as possible to the position which was previously occupied by the occlusal plane of the natural teeth (1,2). Once, when the occlusal plane orientation is lost by complete or partial edentulism, it should be relocated correctly by means of a prosthodontic restoration. Over the last century investigators have used various methods and advocated many anatomical landmarks to aid in correct occlusal plane orientation and position (1-13), nevertheless, none of them being completely accurate and satisfactory. Most textbooks on removable prosthodontics advocate that occlusal plane should be parallel to Camper’s line.s Aim of the study: To check the accuracy of using the parallelism with Camper’s plane for establishing level and inclination of occlusal plane in a clinical practice. Materials and methods: Fifty seven dental students with complete natural dentition and Angle Class I participated. Left profile of ten participants with a subject in a natural head position and clenching on a Fox plane and a quick mounting face bow mounted, were photographed from a distance of 1.5 m (Figure 1A). Irreversibile hydrocolloid impressions were made, casts were poured in a hard stone and mounted in a S.A.M. 2P articulator (Figure 1B). An inclination between a Fox plane and a Face-bow plane was measured on the photographs, as well as an inclination between occlusal plane on the mounted casts and the articulator’s horizontal plane. There was no significant difference between the angles: Fox plane : quick-mounting face bow (FP-FB) and occlusal plane : articulator’s horizontal plane (OP-AHP) (P>.05) of the same individuals, so this method was considered reliable. To assess the inclination between the Fox plane and the Camper’s plane the angle between them was measured in all 57 profile digital photographs using ISSA software (Vams, Zagreb) (Figure 2). To test the significance of the difference bertween them, statistical analysis was made (descriptives, one sample t-test). Test value was zero in the one-sample t test, since the Camper’s plane and occlusal (Fox) plane have been supposed to be parallel. Figure 1. A: Subject clenching a Fox plane and having a quick-mounting face bow positioned (left profile); 1B: Casts in S.A.M. 2P articulator Results: Mean difference between Fox plane and Camper plane was: x = - 4.1 degrees, SD = 5.6 degrees. The range of inclination between the 2 planes varied from – 15 to + 10.5 degrees. The angle between the Fox plane and the Camper’s plane was significantly different from zero (no parallelism) for both gender (Males: t = -7.9, df = 18, P<.01; Females: t = -2.35, d.f. = 37; P=0.024). Figure 2. Discussion:It is considered that occlusal plane (FoxP) and Camper’s plane should be parallel, since the most textbooks on prosthodontics advocate this method for establishing the inclination of occlusal plane posteriorly. According to the results of this study, the difference between CP and FoxP was 4.1 degrees and one-sample t test showed that the difference was statistically significant (p<0.01, Table 1). However, the intersubjects variability (standard deviation) was also high. This is in accordance with some other authors (4,12-14). The results suggest that the CP is not a reliable landmark for establishing the occlusal plane posteriorly, because of the statistically significant divergence between CP and FoxP. Koller et al. (15) reported no parallelism between occlusal plane on new dentures and Camper’s plane. Nissan also found no correlation between the two planes after cephalometric analysis of complete denture wearers (4), as well as Karkazis and Polyzois (10, 16), who concluded that both the natural and artificial occlusal planes were not parallel to Camper's plane. Photographic evaluation of craniofacial characteristics has been already profitably utilized in orthodontics and other fields in dentistry and showed to be acceptably reproducible in earlier studies (14, 17-20). 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