Comparative biomechanical analysis of four different tooth- and bone-borne frog appliances for molar distalization : A three-dimensional finite element study.

PURPOSE: The purpose of this study was to analyze the biomechanical effects of four different designs of frog appliances for molar distalization using finite element analysis. METHODS: A three-dimensional finite element model including complete dentition, periodontal ligament, palatine, and alveolar bone was established. Four types of frog appliances were designed to simulate maxillary molar distalization: tooth-button-borne (Type A), bone-borne (Type B), bone-button-borne (Type C), and tooth-bone-borne (Type D) frog appliances. A force of 10 N was applied simulating a screw in the anteroposterior direction. To assess the von Mises stress distribution and the resultant displacements in the teeth and periodontal tissues, geometric nonlinear theory was utilized. RESULTS: Compared to the conventional tooth-borne frog appliance (Type A), the bone-borne frog appliances showed increased first molar distalization with enhanced mesiolingual rotation and distal tipping, but the labial inclination and intrusion of the incisors were insignificant. When replacing the palatal acrylic button with miniscrews (Types B and D), more anchorage forces were transmitted from the first premolar to palatine bone, which was further dispersed by the assistance of a palatal acrylic button (Type C). CONCLUSIONS: Compared to tooth-borne frog appliances, the bone-borne variants demonstrated a clear advantage for en masse molar distalization. The combined anchorage system utilizing palatal acrylic buttons and miniscrews (Type C) offers the most efficient stress distribution, minimizing force concentration on the palatine bone.

Tooth movement with dental anchorage vs. skeletal anchorage: A systematic review of clinical trials.

The aim of this study is to compare the time and movement of orthodontic treatment using dental anchorage and skeletal anchorage in adolescent and adult patients with dental malocclusions. A systematic search was conducted in the Embase, PubMed, Lilacs, Cochrane, Trip, and Scopus databases up to October 2022. All the articles were selected using title and abstract, applying the inclusion and exclusion criteria. Disagreements were resolved with a third author. Finally, a full-text selection took place. The data extraction was conducted by two authors who independently evaluated the risk of bias. The methodological quality of the randomized clinical trials was evaluated using the Cochrane tool for the evaluation of the randomized clinical trials. Six articles were included in the data analysis. There were four clinical trials and two randomized clinical trials. A total of 176 patients was obtained with an age range between 14 and 46 years. Four studies showed significant differences when comparing the two anchorages in retraction or distalization of tooth groups, and two showed no differences when using dental and skeletal anchorage for vertical movements; only the articles with vertical movements showed relapse. We can conclude that skeletal anchorage generates precise and stable horizontal movements without overloading or changing the position of the molar. Future studies must incorporate three-dimensional technology for greater clinical accuracy.

Comparison of Different Types of Palatal Expanders: Scoping Review.

Maxillary bone contraction is caused by genetics or ambiental factors and is often accompanied by dental crowding, with the possibility of canine inclusion, crossbite, class II and III malocclusion, temporomandibular joint disorder, and obstructive sleep apnea (OSAS). Transverse maxillary deficits, in which the maxillary growth is unusually modest, are frequently treated with maxillary expansion. The purpose of this study is to compare the dental and skeletal effects of different types of expanders, particularly the Leaf Expander, rapid and slow dental-anchored or skeletal-anchored maxillary expanders. METHODS: We chose studies that compared effects determined by palatal expansion using a rapid palatal expander, expander on palatal screws, and leaf expander. RESULTS: Reports assessed for eligibility are 26 and the reports excluded were 11. A final number of 15 studies were included in the review for qualitative analysis. CONCLUSIONS: Clinically and radiographically, the outcomes are similar to those obtained with RME and SME appliances; Therefore, it might be a useful treatment choice as an alternative to RME/SME equipment in cases of poor patient compliance or specific situations. Finally, all of the devices studied produce meaningful skeletal growth of the palate. The use of skeletally anchored devices does, without a doubt, promote larger and more successful growth in adolescent patients.

Initial forces experienced by the anterior and posterior teeth during dental-anchored or skeletal-anchored en masse retraction in vitro.

OBJECTIVE: To investigate initial forces acting on teeth around the arch during en masse retraction using an in vitro Orthodontic SIMulator (OSIM). MATERIALS AND METHODS: The OSIM was used to represent the full maxillary arch in a case wherein both first premolars had been extracted. Dental and skeletal anchorage to a posted archwire and skeletal anchorage to a 10-mm power arm were all simulated. A 0.019 × 0.025-inch stainless steel archwire was used in all cases, and 15-mm light nickel-titanium springs were activated to approximately 150 g on both sides of the arch. A sample size of n = 40 springs were tested for each of the three groups. Multivariate analysis of variance (α = 0.05) was used to determine differences between treatment groups. RESULTS: In the anterior segment, it was found that skeletal anchorage with power arms generated the largest retraction force (P < .001). The largest vertical forces on the unit were generated using skeletal anchorage, followed by skeletal anchorage with power arms, and finally dental anchorage. Power arms were found to generate larger intrusive forces on the lateral incisors and extrusive forces on the canines than on other groups. For the posterior anchorage unit, dental anchorage generated the largest protraction and palatal forces. Negligible forces were measured for both skeletal anchorage groups. Vertical forces on the posterior unit were minimal in all cases (<0.1 N). CONCLUSIONS: All retraction methods produced sufficient forces to retract the anterior teeth during en masse retraction. Skeletal anchorage reduced forces on the posterior teeth but introduced greater vertical forces on the anterior teeth.