The dimensions of mandibular lingual tissues relative to the placement of a lingual bar major connector.

PURPOSE: The purpose of this investigation was to measure and describe the lingual tissues of the anterior mandible to determine the acceptable boundaries of the zone of nonmovable tissue for placement of a lingual bar and to compare these to existing numerical guidelines. MATERIALS AND METHODS: Eighty subjects, grouped by age and gender, with clinically normal mandibular lingual gingival tissues from second premolar to second premolar were examined. The lingual sulcular depths (AB) and the distance from the gingival crest to movable tissue of the floor of the mouth (AC) were recorded. The zone of lingual nonmovable tissue was calculated (AC - AB) for each tooth. RESULTS: For all subjects, the mean value of the probing depth (AB) ranged from 1.22 mm (+/-0.33 mm) for central incisors to 1.66 mm (+/-0.43 mm) for second premolars. The mean distance from the gingival crest to movable tissue of the floor of the mouth (AC) ranged from 7.44 mm (+/-1.59 mm) for central incisors to 10.28 mm (+/-2.55 mm) for second premolars. The mean height of the lingual nonmovable tissue (the zone available for the lingual bar; AC - AB) ranged from 6.22 mm (+/-1.59 mm) for central incisors to 8.63 mm (+/-2.57 mm) for second premolars. Most subjects presented with the minimum zone of nonmovable tissue at the central incisors, but with increasing age more subjects presented with minimum values at the posterior teeth. The multifactorial analysis of variance (ANOVA) for males' available nonmovable tissue shows significance for both tooth (p <0.001) and age (p <0.001) factors. The multifactorial ANOVA for females' available nonmovable tissue shows significance for both tooth (p <0.001) and age (p <0.001) factors. Of all subjects, 85% (88% of males, 83% of females) had 4 mm or more of nonmovable tissue, sufficient for a lingual bar. The amount of available room decreased in older females. CONCLUSION: Within the limits of this study, the use of actual measurements of lingual tissues versus existing numerical guidelines increased the percentage of patients for which the lingual bar can be used from approximately 6% to approximately 85%.