CLINICAL
the patient was instructed to clench the posterior teeth 200 times per day to prevent these teeth from erupting in order to gain the most incisor intrusion possible. Figures 2B and 2D show the final result with the reduction of the initial gummy smile. This procedure, although successful, is timeconsuming and must be done carefully to obtain as much intrusion of the maxillary incisors without erupting the posterior dentition. An efficient alternative to this procedure is to prevent these incisors from over erupting in the first place. In a study of 526 children by Keski-Nisula, et al.,9 24% of children whose average age was 5.1 years had gummy smiles exceeding 5 mm. Figures 3A-3F show a patient where the maxillary incisors were prevented from over erupting developing a deep overbite. The patient wore a preformed NiteGuide “C” series (Figure 4A) and an Occlus-o-Guide® “G” series (Figure 4B) while sleeping. Since this Nite-Guide procedure easily corrects gummy smiles, this study was designed to discover the mean changes of the contributing factors of gummy smiles with excessive overbites and over eruption of maxillary incisors during the transitional dentition period from 6 to 8 years of age compared to similar non-treated controls.
Figure 3A: The initial view of a 5.7-year-old patient
Figure 3C: Close-up of initial gummy smile
Figure 3E: Initial overbite with line drawn to show over eruption of deciduous incisors
Figure 3B: The final view after 27 months of passive Nite-Guide wear - 7.9 years of age
Figure 3D: Close-up of final smile
Figure 3F: Final view of correction
Method and materials The experimental sample consisted of 17 Caucasian patients of North European ancestry (13 females and 4 males) with a mean initial age of 5.9 years of age with deciduous overbites exceeding 1.5 mm and a mean overbite of 3.59 mm. Lateral cephalometric radiographs were taken initially and at the end of a mean period of 18 months after full contact of the mandibular permanent incisors with the maxillary permanent central incisors. The experimental group wore an Eruption Guidance® appliance (Nite-Guide “C” series if the first permanent molars were not yet erupted or an Occlus-o-Guide “G” appliance if these molars had already erupted) only while sleeping in order to guide the erupting permanent incisors into the arch. The serial control sample was obtained from the Denver Growth Sample of the Child Research Council of the University of Colorado (10) and consisted of 20 individuals with the same percentage distribution of females (N=15) and males (N=5) (as the treatment sample and as reported in the literature for the general population). The mean initial age of the Volume 4 Number 4
Figure 4A: The Nite-Guide “C” series for the deciduous dentition - worn passively while sleeping
control sample was 5.6 years, and the final mean age was 8.0 years. There were no significant differences between males and females in 85% of the variables in this study, and as a result, the sexes were pooled in the experimental and control groups to simplify the presentation of data. The mean initial overbite of the control group was 2.44 mm (+ 1.16), and the final permanent overbite was 4.16 mm (+ 0.97). The dimensions measured for both groups at the initial and final stages were the overbite, face height, and the incisal edges of the maxillary central incisors to the palatal line (ANS-PNS) and to menton. The tracing technique and accuracy
Figure 4B: The Occlus-o-Guide “G” series for the mixed dentition - worn passively while sleeping
of these measures have been previously described,10 and all measures were calculated to within 0.1 mm using magnification and a calibrated micrometer. Statistical comparisons were performed using the t-test, and all cephalometric measurements were compensated for enlargement.11 Clinical crown heights of maxillary central incisors were measured on six cross-sectional samples of plaster casts selected at random from the author’s practice at 6, 8, and 12 years of age. The means of the clinical crown height at 6, 8, and 12 years were 4.9 mm, 7.7 mm, and 8.9 mm respectively. The crown heights, Orthodontic practice 17