Factors associated with mandibular deviation and proposed classification and treatment guidelines for applying mandibular guidance: A retrospective analysis of 185 patients with segmental mandibulectomy.

Statement of problem: Mandibular guidance therapy is the preferred treatment for patients with segmental mandibulectomy after oncological surgeries. Clinicians face difficulty in decision making and delivering appropriate prosthetic treatment for the rehabilitation of these patients because of the lack of published information.

Purpose: The purpose of this retrospective analysis was to evaluate the factors associated with mandibular deviation and to introduce a classification system of mandibular deviation and prosthetic guidelines for rehabilitating patients with segmental mandibulectomy using a mandibular guidance appliance (MGA).

Material and methods: A total of 185 patients with segmental mandibulectomies without bony reconstruction were evaluated from July 2019 to July 2022 for factors affecting the mandibular deviation and the feasibility of rehabilitating these patients with various types of MGA. Patients reconstructed with a free fibula osteocutaneous flap and those who underwent marginal mandibulectomies without mandibular deviation were excluded from the analysis. Based on the extent of mandibular deviation, the condition of oral tissues, and the functional activity, patients were classified into 1 of 5 classes and treated with an appropriate MGA. Data were analyzed with the Kruskal-Wallis and Fisher exact tests (α=.05).

Results: Of 185 patients, 45 (24.3%) showed no mandibular deviation and were classified into class I without the need for a guidance appliance; 114 (61.6%) showed mild mandibular deviation, were classified into class II, and were treated with a mandibular guide plane prosthesis (MGPP); 7 (3.8%) showed moderate mandibular deviation, were classified into class III, and were treated with a progressive mandibular guide plane prosthesis (Progressive MGPP); 5 (2.7%) showed severe mandibular deviation with fibrosis, were classified into class IV, and were treated with an occlusal ramp prosthesis; and 14 (7.6%) showed compromised oral conditions, were classified into class V, and did not receive any type of MGA. Patients with M0, poorly differentiated squamous cell carcinoma and those who had received radiotherapy showed more mandibular deviation (P<.05). The degree of mandibular deviation increased from Class I to Class IV and was significantly associated with the time gap between surgical intervention and MGA delivery (P<.05).

Conclusions: Radiotherapy and delay in delivering the MGA had a significant effect on mandibular deviation. The proposed classification and prosthetic guidelines were based on the mandibular deviation and will help clinicians in decision making and planning treatment before delivering the MGA.