Double-Blind, Randomized Clinical Trial Comparing One Percent Buffered Versus Two Percent Unbuffered Lidocaine Injections in Children.

Purpose: Buffered local anesthetics offer an alternative to conventional, unbuffered anesthetic formulations; however, evidence about their use in children is scant. The purpose of this study was to determine the anesthetic and physiologic differences associated with the use of buffered one percent and unbuffered two percent lidocaine (both with 1:100,000 epinephrine) in children. Methods: In this randomized, double-blinded, crossover study, 25 children ages 10 to 12 years old received two inferior alveolar never blocks, at least one week apart, randomized to alternating sequences of two drug formulations: (1) formula A-three mL buffered one percent lidocaine (i.e., including 0.3 mL of 8.4 percent sodium bicarbonate); or (2) formula B-three mL unbuffered two percent lidocaine. Primary outcomes were mean blood lidocaine levels (15 minutes post-injection), timing of clinical signs onset, response to pain on injection, and duration of anesthesia. Analyses relied upon analysis of variance for crossover study designs and a P<0.05 statistical significance criterion. Results: The buffered formulation resulted in significantly lower mean blood lidocaine levels compared to unbuffered-a 63 percent (P<0.05) weight-adjusted relative decrease. The authors found no important differences in pain upon injection, onset, and duration of anesthesia. Conclusion: The buffered local anesthetic formulation showed equal effectiveness with a double-concentration unbuffered formulation while resulting in lower mean blood lidocaine levels-an important gain for the prevention of anesthetic toxicity.

The association between orthodontic treatment with removal of premolars and the angulation of developing mandibular third molars over time.

OBJECTIVE: To assess changes in mandibular third molar angulation during orthodontic treatment in subjects having either first or second premolars or neither removed. MATERIALS AND METHODS: In a retrospective study approved by the institutional review board, right and left mandibular third molar angulations were compared to the vertical axis of adjacent second molars before and at the end of orthodontic treatment. The sample included 25 subjects with first premolars removed, 25 subjects with second premolars removed, and 24 subjects with no premolars removed. A decrease in angulation over time of at least 5°, so that the third molar became more vertical, was considered clinically favorable. Data were assessed by a linear mixed effect model and a proportional odds model with significance set at P < .05. RESULTS: Prior to treatment, the average mandibular third molar angulation did not differ significantly among the three study groups (P  =  .97). The average change during treatment was not significantly affected by group (P  =  .59), but a higher proportion of mandibular third molars were more vertical by at least 5° in the second premolar extraction group compared to the other two groups at the completion of treatment. CONCLUSION: Although creating space for third molars to erupt and function has intuitive appeal, clinicians should not assume that third molars will move upright to a vertical position even if premolar removal is performed as part of an orthodontic treatment plan.

External apical root resorption in Class II malocclusion: a retrospective review of 1- versus 2-phase treatment.

External apical root resorption (EARR) is an imperfectly understood problem of orthodontic treatment. The records of 138 children with Class II malocclusion (overjet > 7 mm) participating in a randomized clinical trial of early orthodontic treatment were reviewed. The patients were treated in either 1 phase with fixed appliances only (n = 49) or 2 phases with headgear (n = 49) or bionator (n = 40) followed by fixed appliances. The 3 groups were similar in age, sex, and malocclusion severity at enrollment. The records examined included anamnestic data, clinical examination records, panoramic radiographs before and after fixed appliance therapy, and posttreatment periapical radiographs. All radiographs were reviewed and scored independently by 2 examiners for maxillary incisor root development, morphology, and EARR. Of the 532 incisors scored, 11% of central and 14% of lateral incisors demonstrated moderate to severe (>2 mm) EARR. The proportion of incisors with moderate to severe EARR was slightly greater in the 1-phase treatment group. There was no difference in the incidence of EARR between teeth that had had trauma and those that had not, and there was only a slight increase in frequency of root resorption in teeth with unusual root morphology. Significant associations exist among EARR, the magnitude of overjet reduction, and the time spent wearing fixed appliances. However, not all incisors in a child respond in the same way, so other variables must play a role in determining the root response to orthodontic forces.