Changes in occlusal force and occlusal contact area after active orthodontic treatment: a pilot study using pressure‐sensitive sheets

Objective: To test the hypothesis that long-term use of an oral appliance (OA) does not cause changes in the occlusal contact area (OCA). Materials and Methods: Baseline and follow-up treatment study models were obtained for 45 patients with obstructive sleep apnea who had been using an OA for 4 or more days/week for more than 5 years. Study models in centric occlusion, with an inserted pressure-sensitive sheet, were loaded in compression. An image scanner was used to evaluate OCA. Results: A significant change in total OCA was identified in 39 patients (86.7%): a decrease in 26 (66.7%) and an increase in 13 (33.3%) patients. Regional changes Ͼ5% were observed in Ͼ90% of patients in each of the three regions. In the molar and premolar regions, 24 (53.3%) and 27 (60.0%) of the patients showed an OCA decrease, while only 16 (35.6%) and 15 (33.3%) showed an increase. Conversely, for the anterior region, more increases (24 patients-53.3%) than decreases were identified. Conclusion: The hypothesis is rejected. Long-term OA therapy resulted in dramatic changes of occlusion, suggesting that monitoring of occlusal changes is required.

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Changes in Occlusal Contact Area during Oral Appliance Therapy Assessed on Study Models

Ueda

Almeida

Lowe

et al. 2008

“…14 Similar studies included either patients treated with extraction alone 15 or a small number of patients. 16 The purpose of this 2-year follow-up study was to evaluate changes in occlusal contact area and force in nonextraction, two maxillary premolar extraction, and four premolar extraction cases.…”

Section: Introductionmentioning

confidence: 99%

Changes in occlusal function after extraction of premolars: 2-year follow-up

Yoon

Hwang

Chung

et al. 2017

Objective: To determine the effects of extraction and the number of teeth extracted on changes in occlusal function by measuring occlusal contact area and force before and after orthodontic treatment with a fixed appliance. Materials and Methods: Female patients treated with a fixed appliance were divided into nonextraction (n ¼ 36), two maxillary premolar extraction (n ¼ 31), and four premolar extraction (n ¼ 18) groups. Bite pressure-sensitive films were used to analyze the occlusal contact area and force. Measurements were performed before treatment (Pre-Tx), immediately afterward (After-Tx), and 2 years later (2Y After-Tx). The data were analyzed using a linear mixed model and the post hoc Bonferroni test. Results: The occlusal contact area and force after treatment decreased significantly compared with Pre-Tx values but were increased 2 years later in all groups. There were no significant differences in occlusal contact area or force during the entire observation period among the three groups (P . .05). The occlusal contact area and force in the nonextraction and two maxillary premolar extraction groups recovered to Pre-Tx levels 2 years later (P . .05). The occlusal contact area in the four premolar extraction group was significantly lower than the Pre-Tx level after 2 years of retention (P , .05). Conclusions: The occlusal contact area and force showed a tendency to decrease immediately after treatment and then gradually increase to pretreatment levels during the observation period. However, the occlusal contact area did not recover fully after 2 years in the four premolar extraction group. (Angle Orthod. 2017;87:703-708.)

“…[6][7][8] According to the report by Sultana et al, 8 the occlusal force was 431 N in the molar region and 32.5 N in the anterior region. Furthermore, the center of the tooth contacts is known to be anteroposteriorly located in the region of the first molar.…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional finite element analysis of occlusal stress distribution in the human skull with premolar extraction

Choi

Cha

Jang

et al. 2012

Objective: To analyze the effect of orthodontic treatment with premolar extraction on the stress distribution of the occlusal force in the human skull. Materials and Methods: A three-dimensional finite element (3D FE) model was constructed based on computed tomography scan data, and it served as the pretreatment model. For the extraction model simulating postorthodontic occlusion, the first premolar was removed in the pretreatment model, and the anterior and posterior segments were repositioned. Stress distribution was evaluated by 3D FE analysis in both models under the simulation of 1000 N for occlusal forces and 400 N for masseter muscle force. Results: The occlusal stresses were concentrated at the alveolar bone near the teeth, the infrazygomatic crest, the frontal process, the temporal process of the zygomatic bone, the infraorbital rim, the pyriform aperture region, and the pterygoid plate in both models. The von Mises stress at the pterygoid plate area was lower in the extraction model (3.53 MPa) than in the pretreatment model (5.57 MPa), while the stress at the frontal process of the maxilla was higher in the extraction model (2.32 MPa) than in the pretreatment model (2.16 MPa). Conclusions:The results indicated that the occlusal forces were transferred through the maxillonasal, maxillozygomatic, and maxillopterygoid stress trajectories and that stress distribution moved more ''forward'' with the orthodontic treatment with premolar extraction. (Angle Orthod. 2013;83:204-211.)