The effect of early loss of primary molars on tooth eruption and space conditions. A longitudinal study.

In 186 children study casts were made at the age of 9, 11 and 13 years. The material was grouped according to early loss of primary molars and a comparison was made between children with and without early losses. Early loss was defined as follows: 1. extraction of the first primary molar between 7 1/2 and 9 1/2 years and/or extraction of the second primary molar between 7 1/2 and 10 1/2 years; 2. extraction of the first and/or second primary molar before 7 1/2 years of age. The following variables were studied: space conditions, dental stage for groups of teeth, eruption stage of single teeth. For the incisors the clinical crown length (CCL) was used as a measure of the eruption stage. The results showed that there was a tendency to later eruption and later onset of dental stages in cases without early losses when a comparison was made with investigations where this factor had not been taken into consideration. The second permanent molar erupted earlier in both jaws after early loss of the second primary molar. Children with loss of primary molars before 7 1/2 years developed more crowding than children without losses and losses after 7 1/2 years had little effect on the relative space.