Jan Wyatt

Accuracy and surgical feasibility of a CBCT-based stereolithographic surgical guide aiding autotransplantation of teeth: in vitro validation

The aims of this study were to determine the accuracy of a 3D computer model and stereolithographic (STL) replica when compared to the real tooth and to develop a cone beam computed tomography (CBCT)-based planning technique including surgical guide fabrication. A STL surgical guide and a tooth replica were fabricated using SimPlant Pro 12.1. To validate this process, tooth segmentation and replica design were prepared for comparison to an optical scan of the corresponding tooth. For surgical intervention, a dry dentate mandible was scanned using a Scanora CBCT and the donor tooth was segmented. The donor tooth was repositioned, and two guides were designed. These tooth replica and guides were used in socket preparation of the dry mandible. The 3D computer model of the segmented teeth and related STL models showed satisfactory results with an acceptable accuracy. The surfaces were within 0·25mm distance, but in some areas up to 2·5mm deviation were seen. The results showed that 79% of the points was between 0·25 and -0·25mm, 3% was overestimated (>0·25mm) and 18% was underestimated (<-0·25mm). The computer-based repositioning of the donor tooth and construction of tooth replica and guide allowed socket preparation before donor tooth extraction and optimization of the STL procedure for in vivo planning of CBCT-based autotransplantation.

Radiation doses of indirect and direct digital cephalometric radiography

Aim The aim of this study was to measure organ doses and calculate the effective dose for indirect and direct digital cephalometric exposures.Material and methods Indirect digital cephalometric exposures were made of a Rando® phantom head using a Cranex Tome® multipurpose unit with storage phosphor plates from Agfa and the direct digital (Charge Coupled Device, CCD) exposures were made with a Proline Ceph CM® unit. Exposure settings were 70 kV and 4 mAs for indirect digital exposures. Direct digital exposures were made with 70 kV, 10 mA and a total scanning time of 23 s. TLD700® dosemeters were used to measure organ doses, and the effective doses were calculated with (effective dosesal) and without inclusion of the salivary glands. A pilot study was carried out to compare diagnostic image quality of both imaging modalities.Results Effective doses were 1.7 μSv for direct digital and 1.6 μSv for indirect digital cephalometric imaging. When salivary glands were included in the calculation, effective dosessal were 3.4 μSv and 2.2 μSv respectively. Organ doses were higher for direct digital imaging, except for the thyroid gland, where the organ doses were comparable. Diagnostic image quality of indirect and direct digital cephalometric images seemed comparable.Conclusion Effective dose and effective dosesal were higher for direct digital cephalometric exposure compared with indirect digital exposure. Organ doses were higher for direct digital cephalography. From preliminary data, it may be presumed that diagnostic image quality of indirect and direct digital cephalometric images are comparable.

Validation of the cone beam computed tomography–based stereolithographic surgical guide aiding autotransplantation of teeth: clinical case–control study

OBJECTIVE To compare the outcome of cone beam computed tomography (CBCT)-based surgical planning and transfer technique for tooth autotransplantation versus conventional autotransplantation. STUDY DESIGN The study material comprised 40 pediatric subjects in whom 48 teeth were transplanted following a case-control design. While the study group (mean age 11 years) underwent CBCT imaging for surgical planning and transfer via stereolithographic tooth replica fabrication, the historical control group (mean age 12 years) was subjected to conventional autotransplantation. RESULTS The CBCT-based preoperative planning and the use of a tooth replica decreased the extra-alveolar time and reduced the number of positioning trials with the donor tooth. In the control group, 6 patients showed 1 or more complications, while this was noticed for only 2 study patients. CONCLUSION CBCT-based surgical planning of tooth autotransplantation may benefit from a shorter surgical time, while being a less invasive technique, causing fewer failures than a conventional approach.

Importance of root development in autotransplantations: a retrospective study of 137 teeth with a follow-up period varying from 1 week to 14 years

The aim of the present study was to perform a retrospective study of autotransplanted teeth with a variable but individually maximized follow-up period in order to provide information on the long-term clinical outcome. The sample was obtained from patients who were treated at the University Hospitals KU-Leuven, Belgium, during the period 1996-2010. Of the total of 109 subjects (137 teeth), 98 patients were invited for recall, of whom 68 patients (87 teeth) responded positively. Eleven out of the 109 patients were excluded due to loss of the transplanted tooth. Although 41 patients had no re-examination visit, clinical and radiological data from all 109 subjects were included in the sample. The follow-up period varied from 1 week of 14.8 years, with a mean of 4.9 years. Transplanted teeth receiving orthodontic treatment had a lower risk of ankylosis and were less likely to fail. The risk of root resorption was lower for teeth with stages one-half to three-quarters of root length at the time of transplantation. Molars were more susceptible to ankylosis. Almost all teeth showed partial or full obliteration of the pulp. Absence of further root development was higher in donor teeth with root length stage less than one-half. Trans-alveolar transplantation was less successful. Autotransplantation can be a valid alternative method in young adolescents for replacing missing teeth because of agenesis or trauma. The optimal time to transplant is when the root has reached two-thirds to three-quarters of the final root length.

Clinical application of a stereolithographic tooth replica and surgical guide in tooth autotransplantation

In recent years rapid prototyping technologies have been an indispensable tool in several studies on diagnosis, treatment planning and oral and maxillofacial surgery. A clinical case is presented employing a cone beam computed tomography (CBCT) based stereolithographic tooth replica and surgical guide in order to reduce injury to the periodontal ligament of the donor tooth in the autotransplantation procedure. Virtual 3D surgery is planned. A tooth replica and surgical guide were fabricated prior to surgery and used during the autotransplantation procedure. The use of stereolithographic models may be advantageous in diagnosis and treatment planning. It provides an accurate method to produce models of donor teeth that serve as prototypes for recipient site preparation in tooth autotransplantation procedures.

Associated parameters of canine impaction in patients with unilateral cleft lip and palate after secondary alveolar bone grafting: a retrospective study

Objectives To compare parameters related to impacted canines at the cleft versus the normal contralateral side and with non-impacted canines at the cleft side in unilateral cleft lip and palate (UCLP) patients. We also aim to search for possible associated parameters enabling prediction of canine impaction in these patients. Materials and methods Ninety-five non-syndromic UCLP patients were included and divided into group A (n = 41 patients) with unilateral impacted canines at the cleft side (A1) and spontaneously erupted canines at the non-cleft side (A2) and group B with spontaneously erupted canines at the cleft side (n = 54 patients). Clinical information and radiographic parameters on panoramic radiographs were collected and compared between groups using a generalized linear mixed model, a Mann-Whitney U-test, a Fishers exact test, and receiver operating characteristic tests. Results Impaction of the maxillary canine at the cleft side in UCLP patients can be suspected in case of delayed canine root development, a higher vertical position and sector score (P < 0.05) and higher angles between the canine and the midline, as well as between canine and lateral incisor and between first premolar (P < 0.001). Results clearly indicate that the erupting canine position at the cleft side, even when not impacted, is different from the non-cleft side. Conclusion There is a great risk for canine impaction at the cleft side in UCLP patients when the canine position is more apical than one-third of the root of the adjacent lateral incisor and when the angles between canine and midline and between canine and first premolar are higher than 23.82 and 16.1 degrees, respectively. These associated parameters should have to be studied in a prospective setting to confirm their predictive value.