Improvement of the Impacted Level of Lower Third Molars After Orthodontic Treatment.

OBJECTIVES: The early or delayed surgical removal of an asymptomatic lower third molar (M3) in orthodontic patients remains controversial. This study aimed to determine the changes in the impacted level of M3 such as angulation, vertical position, and eruption space, after orthodontic treatment in 3 groups, namely non-extraction (NE), first premolar (P1) extraction, and second premolar (P2) extraction. METHODS: Relevant angles and distances related to 334 M3s from 180 orthodontic patients were assessed pre- and posttreatment. Angle between lower second molar (M2) and M3 (M3-M2) was used for evaluating M3 angulation. For M3 vertical position, distances from occlusal plane to the highest cuspid (Cus-OP) and fissure (Fis-OP) of M3 were used. Distances from the distal surface of M2 to anterior border (J-DM2) and centre (Xi-DM2) of the ramus were used for assessing M3 eruption space. Pre- and posttreatment values of the angle and distance in each group were compared using a paired-sample t test. Measurements of the 3 groups were compared using analysis of variance. Hence, multiple linear regression (MLR) analysis was used to determine significant factors that impacted changes in M3s' related measurements. Independent factors used for MLR analysis included sex, treatment starting age, pretreatment respective angle/distance, and premolar extraction (NE/P1/P2). RESULTS: M3 angulation, vertical position, and eruption space at posttreatment were significantly different from those at pretreatment in all 3 groups. MLR analysis showed that P2 extraction significantly improved M3 vertical position (P < .05) and eruption space (P < .001). P1 extraction significantly decreased Cus-OP (P = .014) and eruption space (P < .001). Treatment starting age was significant factor that affected Cus-OP (P = .001) and M3 eruption space (P < .001). CONCLUSIONS: After orthodontic treatment, M3 angulation, vertical position, and eruption space changed in favour of the impacted level. These changes in the 3 groups were clearer in order: NE, P1, and P2, respectively.

Efficacy of the Tent-Pole Technique in Horizontal Ridge Augmentation

Abstract Objective: To evaluate the efficacy of the technique for ridge augmentation prior to implant placement. Material and Methods: Six patients with nine sites presenting an initial ridge width of smaller than 4 mm were included in this study. The tent-pole technique (combination of osteosynthesis screws measuring 1.5 mm in diameter, ABBM, and resorbable collagen membrane) was applied at defect sites. After eight months of healing time, implants were placed in the treated sites. The primary outcomes (radiographic initial ridge width, re-entry ridge width, ridge width gain) were measured by cone-beam computed tomography in reference buccopalatal cross-sections and the secondary outcomes (clinical parameters) were recorded by a digital caliper at the first and second stages. Results: After grafting, the radiographic ridge width increased by 3.02 ± 1.11 mm (1.57-4.75 mm) at 2 mm below the crest and 3.32 ± 1.70 mm (0.23-5.66 mm) at 6 mm below the crest significantly (p< 0.05). For clinical results, the mean horizontal dimension gain was 3.21 ± 1.04 mm (1.83-4.57 mm), while the mean reduction in dimension was 0.38 ± 0.33 mm. These results were statistically significant (p<0.05). Uneventful healing and no infections or membrane exposure were recorded at all sites during the study process. Three of nine (33.33%) defect sites required additional bone grafting. Conclusion: The tent-pole technique is an effective method for increasing the horizontal ridge dimension, minimizing postoperative complications, and facilitating subsequent implant placement.