Jeremy Knox

Cardiff University, Cardiff, Wales, United Kingdom

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Publications (18)8.1 Total impact

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    ABSTRACT: summaryTo investigate the feasibility of facial laser scanning in pre-school children and to demonstrate landmark-independent three-dimensional (3D) analyses for assessment of facial deformity in 5-year-old children with repaired non-syndromic unilateral cleft lip and/or cleft palate (UCL/P).Faces of twelve 5-year-old children with UCL/P (recruited from university hospitals in Cardiff and Swansea, UK) and 35 age-matched healthy children (recruited from a primary school in Cardiff) were laser scanned. Cleft deformity was assessed by comparing individual faces against the age and gender-matched average face of healthy children. Facial asymmetry was quantified by comparing original faces with their mirror images.All facial scans had good quality. In a group of six children with isolated cleft palate coincidence with the average norm ranged from 18.8 to 26.4 per cent. There was no statistically significant difference in facial asymmetry when compared with healthy children (P > 0.05). In a group of six children with UCL with or without cleft palate coincidence with the average norm ranged from 14.8 to 29.8 per cent. Forehead, midface and mandibular deficiencies were a consistent finding, ranging from 4 to 10mm. The amount of 3D facial asymmetry was higher in this group (P < 0.05).Facial laser scanning can be a suitable method for 3D assessment of facial morphology in pre-school children, provided children are well prepared. Landmark-independent methods of 3D analyses can contribute to understanding and quantification of facial soft tissue cleft deformity and be useful in clinical practice.
    The European Journal of Orthodontics 10/2012; · 1.08 Impact Factor
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    ABSTRACT: A novel removable rapid maxillary expansion appliance is described for use in routine clinical practice. The laboratory construction and clinical technique is described, and the advantages of the appliance over conventional rapid expansion devices are highlighted.
    Journal of Orthodontics 12/2010; 37(4):272-8.
  • Journal of Orthodontics 12/2010; 37(4):317-8.
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    ABSTRACT: The provision of orthodontic anchorage in the adult patient can be compromised due to reduced periodontal support, insufficient number of teeth and limited supra-gingival tooth tissue. Where tooth borne anchorage is unavailable for significant orthodontic movement implants represent a viable alternative. This paper describes the use of dental implants for orthodontic anchorage in a partially dentate patient with a severe unilateral cross-bite where orthognathic surgery was the only other realistic option. The implants were successfully engaged using a composite bridge and a modified quad helix appliance for correction of the malocclusion. Once orthodontics was completed the patient was restored using highly sintered ceramic crowns and bridges. This paper highlights the importance of the multi-disciplinary team and the close liaison between the restorative dentist, orthodontist and technician in treatment planning and provision.
    The European journal of prosthodontics and restorative dentistry 09/2010; 18(3):123-7.
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    ABSTRACT: To evaluate the accuracy and reproducibility of a three-dimensional (3D) optical laser-scanning device to record the surface detail of plaster study models. To determine the accuracy of physical model replicas constructed from the 3D digital files. A method comparison study using 30 dental study models held in the Orthodontic Department, School of Dentistry, Cardiff University. Each model was captured three-dimensionally, using a commercially available Minolta VIVID 900 non-contact 3D surface laser scanner (Konica Minolta Inc., Tokyo, Japan), a rotary stage and Easy3DScan integrating software (TowerGraphics, Lucca, Italy). Linear measurements were recorded between landmarks, directly on each of the plaster models and indirectly on the 3D digital surface models, on two separate occasions by a single examiner. Physical replicas of two digital models were also reconstructed from their scanned data files, using a rapid prototyping (RP) manufacturing process, and directly evaluated for dimensional accuracy. The mean difference between measurements made directly on the plaster models and those made on the 3D digital surface models was 0.14 mm, and was not statistically significant (P = 0.237). The mean difference between measurements made on both the plaster and virtual models and those on the RP models, in the z plane was highly statistically significant (P <0.001). The Minolta VIVID 900 digitizer is a reliable device for capturing the surface detail of plaster study models three-dimensionally in a digital format but physical models of appropriate detail and accuracy cannot be reproduced from scanned data using the RP technique described.
    Journal of orthodontics 09/2008; 35(3):191-201; discussion 175.
  • Karl Bishop, Liam Addy, Jeremy Knox
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    ABSTRACT: In this fourth and final paper on the management of patients with congenitally missing teeth, the use of dental implants is considered. This group of patients often provides unique challenges when implant reconstruction is considered. Often a multidisciplinary approach is required involving orthodontists, oral surgeons and restorative dentists. The use of dental implant systems is a rapidly developing area of dentistry and its implications on hypodontia are discussed. This paper identifies the problems associated with a congenital absence of teeth and addresses their management in relation to the use of implants. Clinical Relevance: The use of dental implants in hypodontia patients should always be considered as a treatment option. These groups of patients, however, require careful planning, often of a multidisciplinary nature, so that the timing of the various treatment modalities is seamless.
    Dental update 04/2007; 34(2):79-80, 82-4.
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    ABSTRACT: The term 'amelogenesis imperfecta' (AI) describes a diverse group of hereditary conditions primarily affecting the quality and/or quantity of dental enamel. This paper describes a case in which hypoplastic AI with delayed/failure of eruption of the permanent teeth was shown to be associated with renal calcification. Given the importance of the renal involvement, the authors suggest that paediatric dentists consider referring all children with this dental phenotype for renal ultrasound examination.
    International Journal of Paediatric Dentistry 02/2007; 17(1):62-5. · 0.92 Impact Factor
  • Karl Bishop, Liam Addy, Jeremy Knox
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    ABSTRACT: Restoration of spaces in hypodontia patients needs to take into account many factors including, the number of missing teeth, the distribution of space, the size of the teeth, and the age of the patient. This paper considers adhesive and conventional bridgework, as well as removal alternatives for the restoration of spaces. The various merits of each are discussed, together with treatment planning considerations for such cases.
    Dental update 01/2007; 34(1):30-2, 34, 37-8.
  • Liam Addy, Karl Bishop, Jeremy Knox
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    ABSTRACT: Managing edentulous spaces in patients with congenitally missing teeth demands careful planning and, often, a multidisciplinary approach. Orthodontic tooth movement can be considered to close spaces as well as improve the distribution of available teeth. In this second paper, the advantages of a collaborative approach are discussed.
    Dental update 01/2007; 33(10):592-5.
  • Karl Bishop, Liam Addy, Jeremy Knox
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    ABSTRACT: The management of patients with congenitally missing teeth can be a challenge and, in many cases, requires multidisciplinary care. In this four-part series, a contemporary approach to managing this group of patients is discussed. This first paper examines the terminology, epidemiology and restorative challenges that such patients can exhibit.
    Dental update 12/2006; 33(9):531-4, 537.
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    ABSTRACT: This article describes construction of the average face and its application in the clinical environment. A total of 72 children, mean age 11.8 years, were selected for the study. Laser-scanned images of the subjects were obtained under a reproducible and controlled environment with 2 Minolta Vivid 900 (Minolta, 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 seconds. These scanned images were processed and merged to form a composite 3-dimensional soft tissue reproduction of the subjects using commercially-available reverse modeling software. The differences in facial morphology were measured using shell deviation color maps. The average face was used to compare differences between male and female groups and 3 subjects with craniofacial anomalies. The difference between the average male and female face was 0.460 +/- 0.353 mm. The areas of greatest deviation were at the zygomatic area and lower jaw line, with the males being more prominent. The results of the surface deviation between the subjects with craniofacial anomalies were significant. The construction of the average face provides an interesting perspective into measuring changes in groups of patients and also acts as a useful template for the comparison of craniofacial anomalies.
    Journal of Oral and Maxillofacial Surgery 08/2006; 64(7):1086-92. · 1.33 Impact Factor
  • Journal of Biomechanics. 01/2006; 39(Supplement 1):S201-S202.
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    ABSTRACT: Decalcification is a significant problem during fixed orthodontic treatment. Topical Fluorides can reduce or eliminate the problem, but the relative effectiveness of different treatments or combinations of topical fluoride preparations is unknown. This systematic review was undertaken to determine the effectiveness of topical fluoride preparations in preventing decalcification during fixed orthodontic treatment. A wide search of published and unpublished material in any language was undertaken by using general and specialist databases; key dental journals were searched by hand. Predefined inclusion criteria based on objective outcome measures of decalcification, duration of treatment, presence of a comparison group, and study design were applied to determine study selection. Included studies were double extracted onto pre-designed data extraction sheets. By screening titles and abstracts, we identified 143 articles; after the inclusion criteria were applied, 7 reports (of 6 studies) remained. Differences in the methodologies and reporting made statistical analysis impossible. However, the use of topical fluorides in addition to fluoride toothpaste reduced the incidence of decalcification in populations with both fluoridated and non-fluoridated water supplies. Different preparations and formats appear to decrease decalcification, but there was no evidence that any 1 method was superior. There was some evidence that the potency of fluoride preparations might be important.
    American Journal of Orthodontics and Dentofacial Orthopedics 12/2005; 128(5):601-6; quiz 670. · 1.46 Impact Factor
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    ABSTRACT: The purpose of this prospective clinical trial was to evaluate the reliability of a 3-dimensional facial scanning technique for the measurement of facial morphology. A field study was conducted in 2 comprehensive schools in the South Wales region of the United Kingdom. Forty subjects, mean age 11 years 3 months, were analyzed for soft tissue changes at baseline (T1), within 3 minutes (T2), and 3 days later (T3) by using 2 commercially available Minolta Vivid 900 (Osaka, Japan) laser-scanning devices assembled as a stereo pair. Left and right images were merged to form the whole face, and these images were superimposed to assess the errors at T1 and T2, and T1 and T3. The results showed that premerged left and right mean shell deviations were 0.38 +/- 0.14 mm for scans at T1, 0.31 +/- 0.09 mm at T2, and 0.34 +/- 0.12 mm at T3. The mean differences of the merged composite face were 0.31 +/- 0.08 mm between T1 and T2, and 0.40 +/- 0.11 mm between T1 and T3. Paired t tests showed no significant difference between these groups (P > .05). Shell deviation facial maps of the merged scans showed that 90% of the created composite facial scans were within an error of 0.85 mm. Capturing the soft tissue morphology of the face with this technique is clinically reproducible within 3 minutes and 3 days of the initial records.
    American Journal of Orthodontics and Dentofacial Orthopedics 10/2005; 128(4):424-30. · 1.46 Impact Factor
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    ABSTRACT: 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.
    International Journal of Paediatric Dentistry 04/2005; 15(2):127-30. · 0.92 Impact Factor
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    ABSTRACT: This study investigated the feasibility of measuring soft tissue morphology in children using a three-dimensional laser-scanning device. Sixty subjects (30 adults, 30 children) from the University of Wales, College of Medicine and a large secondary school in South Wales were recruited. The mean ages for the adult and children groups were 28.6 years and 11.6 years respectively. Laser scanned images of the subjects were obtained under a reproducible and controlled environment using 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 seconds. 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 shell deviations between left and right scan of each patient were recorded and analyzed for differences. These differences determined whether the subjects could remain still during the time of the scan. The results showed that the mean differences between shell deviations for the adult and children scans were 0.25 ± 0.09 mm and 0.30 ± 0.09 mm respectively. Paired t-tests showed that the mean error between subject groups was 0.05 ± 0.15 mm (p = 0.18), indicating that there was no statistical or clinical difference between the two subject groups. To conclude, 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.
    01/2005; , ISBN: 0-9549670-0-3
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    ABSTRACT: This was a prospective study carried out on 40 live subjects (20 males, 20 females), mean age 11 years 3 months, enrolled into the cranio-facial growth study program at the University of Wales, College of Medicine. 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 of the same subject was taken at two separate times, three days apart. The images were processed and merged to form a composite three-dimensional soft tissue reproduction of the subjects using commercially available reverse modelling software (RapidForm 2004). The following measurements were made: shell deviations of two scans at time 1 (T1) and time 2 (T2) and the mean differences of the merged images. The aim of the study was to evaluate the reproducibility of natural head posture as a reliable measurement of three-dimensional soft tissue facial morphology. The mean shell deviations were 0.38 ± 0.14 mm for left and right scans at T1 and 0.34 ± 0.12 at T2. Paired t-tests between these mean shell deviations revealed the mean difference was 0.04 ± 0.17 mm indicating no statistically significant difference between these groups (p > 0.05). The mean difference between the merged composite faces at T1 and T2 was 0.40 ± 0.11 mm. Aligned facial maps of the merged scans (T1 and T2) showed that 90% of the created composite facial scans correlated to one another with an error no more than 0.85 mm, which is clinically acceptable. To conclude, natural head posture is a clinically reliable and reproducible position for measurement of three-dimensional soft tissue morphology in a cohort of young children.
    01/2005; , ISBN: 0-9549670-0-3
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    ABSTRACT: 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.
    International Journal of Paediatric Dentistry 10/2003; 13(5):342-7. · 0.92 Impact Factor