Onderzoek naar op maat gemaakte botfixatieplaten voor de kaak

Rationale: In orthognathic surgery, patients with a dysgnatic deformity are operated to correct their functional and esthetical problems by realigning the mandible and/or maxilla. Recently, colleagues Kraeima et al. have shown promising results by realigning the maxilla using patient specific osteosynthesis (PSO); it improves the accuracy of maxillary translations when compared with the conventional method using manually bent osteosynthesis. In a selection of orthognathic patients, both the upper and lower jaw are operated on, so called bimaxillary surgery. The current study is a follow-up study, where bimaxillary surgery is included in the scope.
In the field of bimaxillary surgery, a much debated question is the order of sequencing the operation, either maxilla-first or mandibula-first. Traditionally, the maxilla is first operated on, followed by the mandible. However, a mandible first approach could theoretically be more precise due to a better condylar seating of the mandible then positioning of the maxilla. Reviewing literature on orthognathic sequencing, there is still limited consensus on which approach can provide the most predictable result.
From the study by colleague Kraeima we can derive an increased accuracy when using PSO compared with conventional maxilla-first surgery. However, the mandible-first sequence was not considered. Seeing the limited consensus in literature on the best sequencing approach, the question is raised whether PSO can increases the accuracy and predictability of 3D planned orthognathic bimaxillary surgery, also when compared with the mandible-first approach. Current data on the accuracy of mandible-first surgery and PSO are not directly comparable; as such an analysis has not yet been reported.

Objective: The primary objective of this study is to answer if PSO increases the accuracy and predictability of 3D planned orthognathic bimaxillary surgery compared to conventional bimaxillary surgery using the mandible-first approach and mini-plate fixation. The secondary objective of this study is to answer if PSO influences the one-year follow-up skeletal stability of the maxillary segment compared to conventional osteosynthesis using mini-plate fixation

Study design: In order to test the difference in accuracy of translation of 3D virtual planning and predictability of outcome, this study requires a randomised controlled prospective trial design. The control group will receive conventional 3D virtually planned mandible-first translation guided by 3D splints and fixed with conventional osteosynthesis and the intervention group will receive 3D virtually planned translation guided patient specifically using maxillary drill- and saw guides and PSO.

Study population: All consecutive patients who will undergo a bimaxillary osteotomy due to a dysgnatic deformities, when eligible according to the inclusion/exclusion criteria, will be asked to participate in this study.

Study site: 1) Department of Oral and Maxillofacial surgery at the University Medical Center Groningen 2) Department of Oral and Maxillofacial surgery at the Martini Hospital Groningen.

Intervention: The intervention in this study is an osteotomy of the upper and lower jaw (bimaxillary osteotomy), performed using patient specific drill- and saw surgical guides and PSO of the maxilla in the intervention group. The control group will receive a care as usual mandible-first osteotomy using splints and conventional osteosynthesis.

Main study parameters/endpoints: The primary endpoint for this study is the geometrical change on dentition level. The baseline is the planned position, compared with the post-operative final position determined from CBCT. CBCT’s of the maxillofacial region will be made according to care as usual in our clinic; pre-operative, 1-wk post-operative, 1-yr post-operative.

It is our hypothesis that the patient receiving patient specific osteosynthesis will have a more accurate result.

Follow-up after 2 weeks and one year

Controle = Bimaxillary osteotomy with conventional mandible-first approach using splint and stock osteosynthesis, Intervention = Bimaxillary osteotomy with patient specific osteosynthesis guided maxilla-first approach.