Laetitia Brocklebank

Developments in autotransplantation of teeth

Transplantation of teeth has been done for hundreds of years. In the late 18th and early 19th century transplants of teeth between individuals were relatively common at specialist dental practices in London. Surprisingly tooth allotransplants have been found to last 6 years on average. In Scandinavia during the 1950 and 1960s autotransplantation of teeth began to be carried out under increasingly controlled conditions. These have proved to be very successful in long term studies with autotransplants surviving up to 45 years post-surgery. Recent developments in cone beam CT and rapid 3D prototyping have enabled the fabrication of accurate surgical templates which can be used to prepare the recipient site immediately prior to transplantation. This has resulted in a drastically reduced extra-oral time for the transplant teeth which can be expected to improve success rates further. Autotransplants provide significant advantages compared to single tooth implants and should be considered the treatment of choice in the growing child.

The virtual human face: Superimposing the simultaneously captured 3D photorealistic skin surface of the face on the untextured skin image of the CBCT scan

The aim of this study was to evaluate the impact of simultaneous capture of the three-dimensional (3D) surface of the face and cone beam computed tomography (CBCT) scan of the skull on the accuracy of their registration and superimposition. 3D facial images were acquired in 14 patients using the Di3d (Dimensional Imaging, UK) imaging system and i-CAT CBCT scanner. One stereophotogrammetry image was captured at the same time as the CBCT and another 1h later. The two stereophotographs were individually superimposed over the CBCT using VRmesh. Seven patches were isolated on the final merged surfaces. For the whole face and each individual patch: maximum and minimum range of deviation between surfaces; absolute average distance between surfaces; and standard deviation for the 90th percentile of the distance errors were calculated. The superimposition errors of the whole face for both captures revealed statistically significant differences (P=0.00081). The absolute average distances in both separate and simultaneous captures were 0.47 and 0.27mm, respectively. The level of superimposition accuracy in patches from separate captures was 0.3-0.9mm, while that of simultaneous captures was 0.4mm. Simultaneous capture of Di3d and CBCT images significantly improved the accuracy of superimposition of these image modalities.

Autotransplantation of an immature premolar, with the aid of cone beam CT and computer-aided prototyping: a case report.

UNLABELLED Autotransplantation of immature teeth has good survival rates, and has benefits over ossointegrated implants in the growing child, but is very technique sensitive. Spiral CT imaging has been previously used in adult patients to enable computer-aided prototyping to produce a surgical template of the donor tooth, further increasing success rates. CASE REPORT The case presented describes management of a 9-year-old girl with the combination of hypodontia affecting the upper lateral incisors as well as a severely ectopic maxillary canine. Cone beam CT was used in combination with computer-aided prototyping to produce a surgical template of an immature mandibular second premolar. The surgical template was used to prepare the transplant site before the donor tooth was extracted, greatly reducing the time from extraction to implantation. By 6 months posttransplant the tooth was clinically sound, and continued root development and laying down of dentine was visible radiographically. DISCUSSION This paper demonstrates the use of a novel technique to aid the surgical procedure of autotransplantation of immature premolar teeth. The use of autotransplantation in this case allowed the difficult situation of two missing units in the upper left quadrant to be reduced to one unit, while retaining symmetry in the upper arch. Compared to previous studies, the use of cone beam CT to create a 3D prototype reduced radiation dose compared to spiral CT and drastically reduced the extra-oral time of the donor tooth from extraction to transplantation.

The novel use of three-dimensional surface models to quantify and visualise the immediate changes of the mid-facial skeleton following rapid maxillary expansion

BACKGROUND The transverse skeletal effects of rapid maxillary expansion (RME) have previously been assessed using cone-beam CT (CBCT). However, to date the majority of studies assess the changes based on two-dimensional slice images, which under utilises the three-dimensional (3D) data captured. This study optimizes the volumetric CBCT data by generating 3D rendered surface models to quantity and visualize the immediate 3D changes of the mid-facial bone surfaces following RME. METHODS The sample consisted of 14 patients who required RME prior to fixed appliances. Pre-treatment (T0) and immediate post expansion (T1) CBCT images were taken. Following superimposition the mid face was divided into six anatomical regions. A one-sample t-test was used to determine if the differences between the two surfaces were significantly ≥0.5 mm. FINDINGS All regions showed a change following RME ≥ 0.5 mm. The maxillary and nasal bones showed 2.3 mm and 2.4 mm expansion respectively, followed by the zygomatic bones (1.4 mm), 2 cases showing asymmetric expansion. CONCLUSIONS The use of 3D surface rendered models allows quantification and visualisation of 3D changes in the mid-facial skeleton at anatomical sites distant of RME activation. Following activation there can be a pan mid-facial expansion, including not only the maxilla but also the nasal lateral bones and zygomas. The response was highly variable and asymmetric expansion can occur.

A comparison of two radiographic assessment protocols for patients with periodontal disease

Objective Radiographic assessment of patients with generalised severe periodontitis may be undertaken with a panoramic view and supplementary periapicals. The purpose of this study was to estimate the effective radiation dose from this form of radiographic assessment, and to compare it with an estimate of the dose from a series of periapicals of all the affected teeth.Design Cross-sectional observational study.Setting Departments of Periodontology and Radiology, Glasgow Dental Hospital and School.Method Fifty consecutive patients [were recruited] with sufficiently widespread advanced periodontitis to require at least seven periapical radiographs. [Following new local guidelines, a panoramic view was taken.] The adequacy of the image of every affected tooth and the number of supplementary periapicals required was determined by a panel of four examiners who also calculated the number of periapicals which would have been taken if panoramic radiography had not been available. An effective dose of 0.001 mSv for one periapical and 0.007 mSv for a panoramic view was assumed.Results The panoramic-plus-periapicals approach delivered an estimated additional effective dose to 86% of patients, in the order of 0.001 – 0.007 mSv.Conclusions Within the parameters of this investigation, the anticipated effective radiation dose from a series of periapical radiographs of all selected teeth would, for the great majority of patients, have been less than the dose from a panoramic-plus-periapicals approach.

The clinical value of X-ray images of the teeth and jaws

X-ray images of the teeth and jaws are required for a variety of diagnostic purposes to supplement a clinical examination, and are invaluable for providing pictorial information about the structures that cannot be examined with direct vision. They can be acquired using traditional film systems which produce analogue images, or using a variety of alternative image receptors which result in a digital image. Irrespective of the method of image acquisition they are utilised by the dental surgeon in order to benefit their patients’ management. Numerous disease processes can affect the teeth and jaws, in addition to a range of developmental abnormalities. These can be classified according to a radiological sieve, which also includes artefactual and iatrogenic features. The key components of the classification are: developmental, inflammatory, traumatic, cystic, neoplastic, osteodystrophies and systemic disorders. This paper will utilise examples of radiographic images of patients to illustrate components of this classification which are unique to the teeth and jaws.