Immediate effects of rapid maxillary expansion on the naso-maxillary facial soft tissue using 3D stereophotogrammetry.

BACKGROUND: Rapid maxillary expansion (RME) is used to expand the narrow maxilla. Dental and skeletal affects have previously been reported but few studies have reported on the overlying soft tissue changes. This study reports on the immediate effects of RME on the naso-maxillary facial soft tissue using 3D stereophotogrammetry. METHODS: Fourteen patients requiring upper arch expansion using RME as part of their full comprehensive orthodontic plan were recruited. Cone beam CT scans and stereophotogrammetry images were taken for each patient; pre-RME activation (T0) and immediately post-RME expansion (T1). Based on twenty-three landmarks, 13 linear and 3 angular measurements were made from each of the stereophotogrammetry images. A linear measurement at ANS was taken from each CBCT image. Using a Wilcoxon signed rank test, the pre-RME and post-RME measurements were compared. RESULTS: The mean separation of the anterior nasal spine was 3.8 mm ± 1.2 mm. The largest median increase was in nasal base width (1.6 mm), which was statistically significant (p = 0.001). Changes in the nasal dorsum height, nasal tip protrusion, philtrum width, and upper lip length were not statistically significant (p < 0.05). No significant differences were observed in the nostril linear measurements, expect for columella width (p = 0.009). Naso-labial angle decreased but was not statistically significant (p = 0.276). The only statically significant angular change was an increase in the nasal tip displacement angle (p = 0.001). CONCLUSION: Rapid maxillary expansion produces subtle changes in the naso-maxillary soft tissue complex. There is an increase in nasal base width, retraction and flattening of the nasal tip. These changes are small, less than 2 mm and variable between patients.

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.

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.

External apical root resorption: two case reports.

AIM: To present two cases of external root resorption and in so doing highlight rarer causative factors as well as the difficulties in classifying root resorption. SUMMARY: Root resorption in the permanent dentition is usually pathological. Local factors are the most frequent causes of resorption, most commonly excessive pressure and inflammation. However, many systemic abnormalities have been implicated in the resorption process. Resorption is often an incidental finding during routine examination. Otherwise, late in the disease process, tooth mobility or infection may arise. A rarer form of root resorption is external apical root resorption which may or may not be linked to systemic disease. In most cases, no causative factors are found. At present there is no curative treatment for external apical root resorption. The current management for these patients is symptomatic, minimal intervention and long-term monitoring. KEY LEARNING POINTS: * Apical resorption may be associated with a systemic disease or of an idiopathic origin. It may also occur in association with orthodontic treatment or with pathoses such as tumours, cysts, etc. * In the absence of signs or symptoms of pulpal and/or periapical disease, endodontic treatment is not indicated. * Long-term monitoring of affected patients is essential.

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 mandibular canal of the edentulous jaw.

The morphology of the mandibular canal after loss of teeth has received little detailed attention. Improved documentation of this topic would allow better interpretation of dental radiographs and would enable those engaged in tooth implantation to better understand the nature of the tissue into which the prostheses are placed. In this study on mandibles from seven dissecting room cadavers panoramic radiographs usually showed the mandibular canal clearly, an incisive canal less so. The wall of the mandibular canal was similar in dentate and edentulous mandibles, and was highly perforated, as suggested by Cryer (Anderson et al., 1991). In edentulous specimens, it was composed mainly of cancellous bone with only occasional single osteons. The inferior alveolar nerve near the mandibular foramen was a large trunk, consisting of three to four nerve bundles with connective tissue sheaths. It became more loosely arranged toward the mental foramen. Medial to the mental foramen, the nerves were frequently in the form of small bundles in the marrow. Any incisive canal was ill-defined and neurovascular bundles, when present, ran through a labyrinth of intertrabecular spaces.

Assessment of zygomatico-orbital complex fractures using ultrasonography.

Twenty-two patients were referred to the maxillofacial surgical unit for assessment and management of suspected fractures of the zygomatico-orbital complex. In each case, both routine plain radiographic and ultrasound examinations were made. The aim of the study was to investigate the sensitivity and reliability of ultrasound to detect such fractures. Imaging with ultrasound was carried out at five areas: the infraorbital margin; lateral wall of the maxillary sinus; zygomatic arch; frontozygomatic process; and orbital floor. Both radiographic and ultrasound findings were correlated with the findings at operation. An overall agreement of 85% between radiographs and ultrasound scans was found. Ultrasound imaging was most reliable at the lateral wall of the maxillary sinus, where the sensitivity was 94% and specificity 100%. The positive predictive value at this area was 100% compared with radiographic findings. We conclude that ultrasound is a useful tool in imaging facial trauma as an initial investigation, and can help to reduce the total number of radiographs required for the diagnosis of fractures of the zygomatico-orbital complex.

Assessment of the radiographic image: recognition of abnormal features.

Radiographs, due to their ability to pass through materials differentially, are used in dental practice to obtain information that is not available by other means. Recognition of the presence of a variation from normal is the first step to accurate interpretation of abnormalities. This article presents an outline of a method for examining radiographs in order to recognize that an abnormality is present, and to learn from the visual information some of the characteristics of the abnormality. A number of clinical examples are used to illustrate the conclusions that we can draw from the radiographic changes.

An audit of occipitomental radiographs.

OBJECTIVES: To audit the justification for and image quality of occipitomental (OM) radiographs obtained at a dental teaching hospital. METHODS: One hundred OM radiographs taken at Glasgow Dental Hospital and their associated request forms were analysed by two examiners retrospectively. Information recorded from the request form included the age and gender of the patient, requesting department, grade of requesting clinician, reason for the request and exposure factors. The radiographs were assessed for radiographic density, patient positioning, presence of abnormality and whether the maxillary sinuses were normal or not. It was then decided by reference to the clinical records if there had been an indication for taking the radiograph. RESULTS: The majority of the requests were from junior staff, most frequently for pain or sinusitis. Almost all were from the Departments of Oral Surgery, Oral Medicine or Dental Accident and Emergency (A&E). The technical quality of the radiographs was variable, especially with respect to superimposition of the petrous temporal bone. Over half of the cases had normal sinuses, no abnormality and no indication for the radiograph. CONCLUSIONS: Many requests were inappropriate and the resultant radiographs had a low diagnostic yield. The technical quality of the radiographs was variable. Guidelines for clinicians for the prescription of OM radiographs were produced and the protocol for radiographic technique changed.

Dental radiology: capture your image.

The use of radiographs to assist in diagnosis and treatment in dentistry relies upon the acquisition of good-quality images. A number of stages involved in this acquisition, and various regulations and guidelines, must be taken into account when selecting equipment, accessories, exposure factors and processing facilities. Each of these areas influence the quality of the image and its potential diagnostic yield. This article reviews the current recommendations that influence the production of a dental radiograph, as a foundation to assessment of the acquired image.

A videofluoroscopic comparison of straw and cup drinking: the potential influence on dental erosion.

OBJECTIVE: Videofluoroscopy was used to compare drinking from a cup with drinking through straws of two varying bore diameters in different positions in the mouth. DESIGN: Clinical study at a single centre. SETTING: UK dental school. SUBJECTS AND METHODS: Twenty patients showing clinical signs of erosion which had necessitated advice and/or treatment. INTERVENTIONS: Subjects drank from a cup and through a narrow straw, which was then repositioned more posteriorly. A wide bore straw was used in two equivalent positions. Swallowing was viewed laterally and anteroposteriorly to assess involvement of incisors and molars respectively. MAIN OUTCOME MEASURES: Video recordings examined for presence or absence of fluid contact with teeth following each swallow. If contact occurred, the time was measured. RESULTS: Fourteen patients avoided fluid contact with both incisors and molars when using a straw. Compared with the cup, significant differences were found with the narrow straw (P = 0.03, 95% confidence interval of 22.6% to 31.6%), the narrow straw repositioned (P = 0.008, 95% confidence interval of 12.3% to 47.1%) and the wide straw repositioned (P = 0.03, 95% confidence interval of 3.1% to 37.5%). Contact time of fluid with anterior teeth was also significantly reduced. CONCLUSIONS: Drinking through a straw positioned toward the back of the mouth may reduce the erosive potential of soft drinks.

Assessment of the radiographic image: recognition of normal features.

The importance of observation, and perception, based upon an appropriate level of knowledge, is introduced in this article as the basis for examining dental radiographs. Normal anatomical features are displayed in radiographs as relative radiolucencies or radiopacities, their precise appearance varying with the technique used and exposure factors. This article addresses some of the points related to initial examination of radiographs, and the influence on the image of a variety of anatomical features. The author presents a logical approach to examining radiographs and illustrates the key anatomical features in the region of the jaws.

The quality of the X-ray image: fault analysis.

Current guidelines encourage dentists to assess the quality of the radiographs that they take as a normal part of their routine, and peer review is recommended on a regular basis. Technical faults or processing errors may result in unsatisfactory diagnostic images. In order to rectify such faults and to prevent their recurrence it is vital that the practitioner is able to recognize them and determine their cause. This article proposes a user-friendly approach to recognition of technical (procedural) faults, and gives advice on their prevention.

Development of equipment for the standardization of skull photographs in personal identifications by photographic superimposition.

The technique of photographic superimposition of postmortem specimens (dried skull or head) positioned identically to the orientation in an antemortem smiling photograph is now a recognized method for personal identification of human remains. Previous methods used to produce the postmortem photographs were problematic as orientation of the specimen could not be easily adjusted and positions were not reproducible. The objective of this paper is to describe the design and method of use of purpose-constructed equipment intended to alleviate these problems. The equipment comprises a skull-holding jig based conceptually on the Royal Berkshire Hospital halo frame. This is mounted on a pan-and-tilt device, incorporating calibrated measurement scales, enabling independent movements in each of the Cartesian coordinates. A camera is attached to an adjustable mount running on twin parallel rails allowing the camera-to-specimen distance to be varied. The equipment has proven to be straightforward in use and offers considerable advantages over previously described methods for producing postmortem photographs.