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Biomedical subjects

C H Kau

Publications and source records attributed to C H Kau.

10 recordsLinked to original sources
PubMed2006

A new method for the 3D measurement of postoperative swelling following orthognathic surgery.

OBJECTIVE: To describe a new method for measuring facial swelling following orthognathic surgery using a 3D laser-scanning device. DESIGN: Prospective clinical trial. Setting and Sample Population -- University Dental Hospital, Wales College of Medicine, Biology Life and Health Sciences. Three subjects requiring bi-maxillary orthognathic surgery were recruited for the study. EXPERIMENTAL VARIABLES: Laser-scanned images of the subjects were obtained under a reproducible and controlled environment with two Minolta Vivid 900 (Osaka, Japan) optical laser-scanning devices assembled as a stereo-pair. A set of left and right scanned images was taken for each subject and each scan took an average of 2.5 s. 3D laser scans were recorded over six time periods (T1 -- pre-surgical scan, postoperatively: T2 -- 1 day, T3 -- 1 week, T4 -- 1 month, T5 -- 3 months and T6 -- 6 months). OUTCOME MEASURE: Facial scans from different time periods were overlaid onto the baseline (T6) facial scan to determine the reduction and changes in swelling following orthognathic surgery. RESULTS: The results showed that swelling could be accurately quantified following surgery. Furthermore, there was a significant reduction in the amount of swelling 1 month postoperatively. Furthermore, the facial morphology returned to approximately 90% of the baseline facial scan at 3 months. CONCLUSION: The 3D laser-scanning device and the method described was a reliable and accurate measure of facial swelling following surgery.

Adult↗
PubMed2006

Facial templates: a new perspective in three dimensions.

PURPOSE: This paper describes the use of adult facial template in gender-specific facial analysis. SUBJECTS AND METHODS: Eighty adults, mean age 24.5, were selected for the study. Laser-scanned images of the subjects were obtained under a reproducible and controlled environment with two Minolta Vivid 900 (Osaka, Japan) optical laser-scanning devices assembled as a stereo-pair. A set of left and right scanned images was taken for each subject and each scan took an average of 2.5 s. These scanned images were processed and merged to form a composite three-dimensional soft tissue reproduction of the subjects using commercially available reverse modelling software. The differences in facial morphology were measured using shell deviation colour maps. The facial template was used to compare differences between males vs. females groups and two subjects with facial disproportions. RESULTS: The difference between the male and female facial templates was 1.28 +/- 1.02 mm. The areas of greatest deviation were at the nasal, zygomatic area and lower jaw line. The results of the surface deviation maps between the templates and subjects with facial disproportion showed that the results could be applied for orthodontic diagnosis. CONCLUSIONS: The construction of the adult facial templates provides an interesting perspective into measuring changes in groups of patients and also acts as a useful template for the comparison of skeletal disproportion.

Adult↗
PubMed2005

The dental management of a patient with hyperimmunoglobulinemia E syndrome: a case report.

Hyperimmunoglobulinemia E recurrent infection syndrome (also known as Job's syndrome) is a rare multi-system primary immunological disorder in which non-immunological abnormalities of the dentition, bones and connective tissue are also seen. A previous study has reported the occurrence of dental abnormalities in three-quarters of individuals diagnosed as suffering from this condition. The present authors report the case of a boy whose prolonged retention of the primary dentition was associated with delayed eruption of permanent teeth. They emphasize the need for early intervention in order to help minimize later orthodontic problems.

Child↗
PubMed2005

The investigation of the changing facial appearance of identical twins employing a three-dimensional laser imaging system.

OBJECTIVE: An investigation to determine the changing facial appearance of identical twins. DESIGN: Clinical study. MATERIALS AND METHODS: Two Minolta Vivid 900 3D optical laser scanners were placed as a stereo pair to capture the soft tissues of a pair of identical twins. Each scan took approximately 2.5 s. The scanned whole faces were superimposed to determine changes in facial morphologies at different time intervals. OUTCOME MEASURES: The shell deviations between left and right scans of each patient were recorded and analysed for differences. Furthermore, final merged faces were overlaid to determine the changes in facial morphology over time. RESULTS: The results showed that changes in height and weight correlated with changes in facial morphology. CONCLUSION: The 3D laser scanning device is a clinically useful tool in the study of facial growth and facial morphology in a pair of twins.

Body Height↗
PubMed2005

Three-dimensional cone beam computerized tomography in orthodontics.

There has been an escalating interest in three-dimensional imaging devices over the last decade. Orthodontists are beginning to appreciate the advantages that the third dimension gives to clinical diagnosis, treatment planning and patient education. This article focuses on the cutting edge technology of cone beam CT, which utilizes conventional X-ray technology and computerized volumetric reconstruction to reproduce a three-dimensional image. A variety of applications and range of issues associated with this technology will be discussed.

Alveolar Process↗
PubMed2004

The feasibility of measuring three-dimensional facial morphology in children.

OBJECTIVE: An investigation to determine the feasibility of measuring soft tissue morphology in children using a three-dimensional laser-scanning device. DESIGN: Prospective clinical trial. SETTING AND SAMPLE POPULATION: University of Wales, College of Medicine and one secondary school in the South Wales region. Sixty live subjects (30 adults, 30 children) were recruited in the study. EXPERIMENTAL VARIABLES: Laser scanned images of the subjects were obtained under a reproducible and controlled environment with two Minolta Vivid 900 (Osaka, Japan) optical laser-scanning devices assembled as a stereo-pair. A set of left and right scanned images was taken for each subject and each scan took an average of 2.5 s. These scanned images were processed and merged to form a composite three-dimensional soft tissue reproduction of the subjects using commercially available reverse modelling software. OUTCOME MEASURE: The shell deviations between left and right scan of each patient were recorded and analysed for differences. These differences determined whether the subjects could remain still during the time of the scans. RESULTS: The results showed that the mean differences between shell deviations for the adult scans and children scans were 0.25 +/- 0.09 and 0.30 +/- 0.09 mm, respectively. Paired t-tests showed that the mean error between subject groups was 0.05 +/- 0.15 mm indicating that there was no difference between the two subject groups (p = 0.18). CONCLUSION: The technique as described is clinically reproducible for children and adults and can be used for studies assessing facial changes due to growth or clinical intervention.

Adult↗
PubMed2004

Extractions as a form of interception in the developing dentition: a randomized controlled trial.

OBJECTIVE: To determine if the extractions of lower primary canines are an effective procedure to relieve crowding of the labial segment. STUDY DESIGN: randomized controlled trial. Subject sample: 83 cases were collected in clinics in Italy, Germany and Wales. The groups were followed over a 2-year period. METHODS: Subjects were randomly allocated to a primary canine non-extraction or extraction group. Dental casts of the patients were collected at the start and at the recall period of the trial. The outcome measures recorded were lower incisor crowding, arch length, intermolar width, overbite, overjet, lower clinical crown heights and lower incisor inclinations. STATISTICS: The Mann-Whitney test was used to compare the differences between the extraction and non-extraction groups. RESULTS: In both groups, crowding reduced 1.27 mm in the non-extraction group and 6.03 mm in the extraction group. The difference between the 2 groups was 4.76 mm (P<0.05). The arch perimeter decreased more in the extraction group by 2.73 mm (P<0.05). As the incisor inclination stayed essentially the same, the loss in arch length was attributed to the molars moving forward. The net gain from extracting deciduous canines was 2.03 mm. CONCLUSIONS: There was a reduction in lower incisor crowding as a result of lower primary canine extraction. However, arch perimeter decreased more in the extraction group leaving less space for the eruption of the lower secondary canines.

Child↗
PubMed2003

Tooth agenesis: a report of missing molars in two generations.

A recent review has suggested that tooth agenesis is becoming more evident in society, though it is not known whether this observation is related to better detection methods and patient awareness or whether there is a real trend towards an increase in prevalence. In this paper we report developmental absence of permanent molars in two generations, and discuss the possible clinical implications of this pattern of tooth agenesis.

Adult↗
PubMedDate not supplied

Repair of new-generation tooth-colored restoratives: methods of surface conditioning to achieve bonding.

The shear bond strength of repaired resin-modified glass-ionomer cements and polyacid-modified composite resins after different methods of surface conditioning was studied. For the resin-modified glass-ionomer cement, none of the surface treatment methods had a significantly higher repair bond strength than the control. For the polyacid-modified composite, the application of low-viscosity resin after treatment with maleic acid, polyacrylic acid, and air abrasion appeared to be of paramount importance, for it enhanced bonding of the repaired specimens.

Acrylic Resins↗