Clinical Accuracy of 3D-Planned Maxillary Positioning Using CAD/CAM-Generated Splints in Combination With Temporary Mandibular Fixation in Bimaxillary Orthognathic Surgery

Study Design

The aim of this study was to evaluate the accuracy of 3-dimensional (3D)-planned maxillary positioning by using computer-assisted design (CAD)/computer-assisted manufacturing (CAM) splints combined with temporary mandibular fixation in bimaxillary orthognathic surgery. In orthognathic surgery, customized splints work sufficiently well to transfer preoperative planning into the operation site for transverse und sagittal positioning of the maxilla. The vertical positioning is more difficult due to the non-fixed mandibular reference. Therefore, the combined use of CAD/CAM splints and temporary mandibular fixation to the zygomatic region was applied for transferring the 3D-planned maxillary position into the operation site from 2012 until 2015 in our hospital.

Objective

In addition to the general accuracy, the precision should therefore be checked especially in the vertical plane compared to axial and sagittal plane.

Methods

In this retrospective study, we calculated the deviation of 5 occlusal landmarks of the maxilla in 35 consecutive patients by fusing preoperative 3D planning images and postoperative computed tomography scans after bimaxillary surgery.

Results

The overall median deviation of maxillary positioning between plan and surgical result was 0.99 mm. The accuracy of left-right positioning was median 0.96 mm. Anterior-posterior positioning of the maxilla showed a median accuracy of 0.94 mm. Just slightly higher values were determined for the upward-downward positioning (median 1.06 mm).

Conclusions

This demonstrates the predictability of maxillary positioning by using CAD/CAM splints in combination with temporary mandibular fixation in all 3 axes.

Factors influencing the long-term prognosis of root tip resected teeth

Introduction: The aim of the study was to investigate possible predictive factors influencing the long-term success of root tip resection. Methods: The retrospective study included 216 patients (♂ 111, ♀ 106, median age 43.3 years). A total of 261 root tip resections were performed on these patients between 1989 and 2012. In addition to determining the success rates 5 and 10 years postoperatively, the factors gender, age, tooth type, use of bone replacement material and preoperative periodontal tooth status were examined with regard to their significance for the long-term prognosis of root tip resected teeth. Results: The evaluation showed an average success rate of 63.6% for all included teeth over the entire observation period (tooth at least one year postoperatively still in situ). The 5-year success rate was 78.2%, the 10-year success rate 63.1%. A dependence of the success rates on the tooth type could not be evaluated. However, the examination showed a clear dependence of the success on the age of the patients. Root tip resections in patients in the age group 60 years and older had significantly worse success rates compared to the age groups 20 to 39 years and 40 to 59 years. The prognosis was also significantly better for patients in the age group 20 to 39 years than for patients in the age group 40 to 59 years. Periodontally compromised teeth showed only a tendency for a poorer prognosis than periodontally healthy teeth. With regard to sex and intraoperative filling of the resection defect with bone replacement material, no differences in the success rates were found. Conclusions: A root tip resection is a good option, largely independent of the type of tooth, to preserve a tooth in the medium to long term after unsuccessful endodontic treatment. However, a revision of the endodontic treatment or even an extraction with subsequent implantation should always be considered as an alternative, especially with increasing age.