Nigel King - Academia.edu (original) (raw)

Papers by Nigel King

Caries Research

Visual attention is a significant gateway to a child’s mind, and looking is one of the first beha... more Visual attention is a significant gateway to a child’s mind, and looking is one of the first behaviors young children develop. Untreated caries and the resulting poor dental aesthetics can have adverse emotional and social impacts on children’s oral health-related quality of life due to its detrimental effects on self-esteem and self-concept. Therefore, we explored preschool children’s eye movement patterns and visual attention to images with and without dental caries via eye movement analysis using hidden Markov models (EMHMM). We calibrated a convenience sample of 157 preschool children to the eye-tracker (Tobii Nano Pro) to ensure standardization. Consequently, each participant viewed the same standardized pictures with and without dental caries while an eye-tracking device tracked their eye movements. Subsequently, based on the sequence of viewed regions of interest (ROIs), a transition matrix was developed where the participants’ previously viewed ROI informed their subsequentl...

Objectives: To evaluate the de/remineralization effects of different amounts of child formula too... more Objectives: To evaluate the de/remineralization effects of different amounts of child formula toothpastes on primary tooth enamel. Design: An in vitro singlesection pH-cycling experimental model. Methods: Sound primary anterior teeth were painted, leaving a 1 mm wide window on the buccal and/or lingual surface prior to being placed in demineralization solution for 96 hours to produce artificial caries lesions 60-100 mm deep. The teeth were then longitudinally sectioned (100 mm thick) and randomly divided into 3 groups. Group A specimens were treated with a pea-sized portion of a non-fluoridated toothpaste while specimens in Groups B and C were treated with half-peasized and pea-sized portions of a 500 ppm F toothpaste, respectively. The pHcycling model was utilized for 7 days. Outcome measurements: Polarized light microscopy and microradiography were used to evaluate the progression of the lesions. Results: Groups A and B lesions increased in depth and area by 60% while those in Group C increased by 20%. There was no significant difference between the non-fluoridated and half-pea-sized portion of the fluoridated toothpaste (p > 0.05); however, a significant difference was found when the non fluoridated and half-pea-size portion were compared with the pea-size portion (p < 0.001, ANOVA and Bonferrini comparison test). Conclusions: Different amounts of child formula fluoridated toothpastes differentially effect the progression of demineralization of early carious lesions. Even though a pea-sized portion of 500 ppm F toothpaste may not promote remineralization of early carious lesion in primary teeth, it slows down the rate of demineralization. Therefore, the reduction of the amount of fluoride toothpaste in order to minimize the risk of fluorosis should be undertaken with great care because it could be expected to compromise the cariostatic effect of toothpastes with a low fluoride content.

BMC Oral Health, 2018

Background: There is relatively little literature on the oral health experiences of individuals w... more Background: There is relatively little literature on the oral health experiences of individuals with Rett syndrome. This study described the incidence of dental extractions and restorations in a population-based cohort, according to a range of demographic and clinical factors. The association between bruxism and age was also investigated. Methods: Existing questionnaire data in the population-based Australian Rett Syndrome Database for the years 2004, 2006, 2009 or 2011 on genetically confirmed female cases (n = 242) were analysed. Results: The incidence rate of restorations and extractions were 6.8 per 100 person years (py) and 9.3 per 100 py respectively. The incidence of extractions decreased with increasing levels of income. Compared to those with a C-terminal mutation, the incidence rate of extraction was higher for those with large deletions (Incidence Rate Ratio (IRR) 4.93; 95% CI 1.46-16.7, p = 0.01). There was a 5% decrease in the risk of frequent bruxism for every one-year increase in age (Risk Ratio 0.95; 95% CI 0.94-0.97). Conclusions: Social advantage may provide some protection for dental health in individuals with Rett syndrome. Those with more severe genotypes seemed to have poorer oral health outcomes.

Pediatric Dental Journal, 2009

Congenital absence of teeth is the most commonly known developmental dental anomaly in humans. Ag... more Congenital absence of teeth is the most commonly known developmental dental anomaly in humans. Agenesis of the permanent first molars has the least frequency of all the tooth types and when present, usually occurs in association with oligodontia or anodontia. Generally, it is easy to diagnose agenesis of the permanent first molars retrospectively, based on the clinical morphology and x-ray photographic features of the permanent second molars; while it is often debatable when made prospectively. Several hypotheses have been promulgated to explain the etiology of hypodontia with evolutionary and anatomic models. Nevertheless, clinical epidemiology does not completely support these hypotheses and therefore clinicians should be cautious; while speculating the missing tooth type based on these hypotheses. We encompass a comprehensive review of the literature on missing permanent first molars and illustrate two cases of missing maxillary permanent first molars to emphasize the complexity involved in their diagnosis. Conversely, among the southern Chinese, the reported prevalence of tooth agenesis for both genders combined is 7.3% and after the third molars, the next most commonly missing tooth type is the mandibular incisor 5,6). Several hypotheses have been promulgated to explain the etiology of hypodontia with evolutionary and anatomic models such as, Butler's field theory 7) , odontogenic polarity, Sofaer's model of compensatory tooth size interactions 8) , Svinhufvud's anatomic model (areas of embryonic fusion) 9) and Kjaer's neuro-osteological developmental fields in the jaws (incisor field, canine/premolar, and molar field) 10). Nevertheless, clinical epidemiology does not completely support these hypotheses and therefore clinicians should be cautious while speculating the missing tooth type based on these hypotheses. For example according to Butler's field theory 7) , the mammalian dentition can be divided into three morphologic fields corresponding to incisors, canines/ premolars, and molars. Within each field, one "key" tooth is presumed to be stable and the neighboring teeth within this field become progressively less stable. Considering each quadrant separately, the

Journal of Dental Research, 2002

The mechanism responsible for sodium-hypochlorite-induced reduction in dentin bond strength and i... more The mechanism responsible for sodium-hypochlorite-induced reduction in dentin bond strength and its reversal with reducing agents is unknown. This study examined the relationship between nanoleakage and reversal of compromised bonding to oxidized dentin. Acid-etched dentin was completely depleted of demineralized collagen matrix when sodium hypochlorite was used. Specimens were bonded with two single-bottle dentin adhesives. They were immersed in ammoniacal silver nitrate for 24 hrs before being processed for transmission electron microscopy. For both adhesives, tensile bond strengths of acid-etched dentin were significantly reduced after sodium hypochlorite treatment, but were reversed when sodium ascorbate was used. After sodium hypochlorite application, reticular nanoleakge patterns in hybrid layers were replaced by vertical, shag-carpet-like patterns along the demineralization front. This type of nanoleakage was completely eliminated after sodium ascorbate treatment with the mat...

Hong Kong Dent J, 2007

Evolution of the different generations of dentin adhesives has been based on extensive clinical a... more Evolution of the different generations of dentin adhesives has been based on extensive clinical and laboratory research, which recognizes the problems related to bonding properties. The purpose of this paper is to provide an update on the current ...

International Journal of Paediatric Dentistry, Jul 1, 2008

Objective. To review the currently available treatment options of anterior open bite. Methods. Se... more Objective. To review the currently available treatment options of anterior open bite. Methods. Search all major dental journals and literature on treatment and management of anterior open bite. Medline search (1960-2006). Literature and data on treatment and management of anterior open bite with keywords 'open bite', 'anterior open bite', 'orthodontic treatment', 'long face', 'vertical dentoalveolar problem' and 'vertical skeletal problem'. Results. Over 50 articles were found and relevant information and data were reviewed by the authors. It was found that the multifactorial nature of anterior open bite makes its management difficult and various treatment modalities are being used. Clinicians must be able to diagnose the problem and choose the best treatment. Conclusion. Successful treatment of anterior open bite greatly relies on both diagnosis and therapeutics. Although there are many different treatment modalities available, stability after treatment is still a critical issue as evidence on long term stability of various treatment options is lacking. Thus, clinicians should pay more attention during retention phase and long-term studies on post-treatment changes and stability should be encouraged.

PubMed, May 29, 2008

Most of the cases of talon cusp in the primary dentition affected the maxillary central incisors,... more Most of the cases of talon cusp in the primary dentition affected the maxillary central incisors, but have no effect on the permanent successors. Among the 5 cases of a talon cusp in primary maxillary lateral incisors reported in the dental literature, however, one was associated with a supernumerary tooth and 3 with supplemental permanent successors. The purpose of this report was to describe 3 cases of a talon cusp on the primary maxillary lateral incisors of Chinese children, all of which were associated with talon teeth or the permanent successors. A conservative approach was used to manage these supplemental permanent lateral incisors, and the advantages of such an approach are discussed.

International Journal of Paediatric Dentistry, May 1, 2007

Background. Most reported cases of talon cusps in the primary dentition have been on the maxilla... more Background. Most reported cases of talon cusps in the primary dentition have been on the maxillary central incisors and the permanent successors have remained unaffected. Four of the five reported cases on a maxillary lateral incisor, however, have been associated with a supernumerary permanent successor.Aim. This paper describes the relationship between the presence of talon cusps on a primary maxillary incisor, and the morphology and number of the permanent successors in a population of Chinese children.Design. The dental records of children diagnosed with a talon cusp on a primary incisor were retrieved for review. The diagnoses took place in a regional school dental clinic in Hong Kong between April 2002 and August 2005.Results. Fifty‐eight primary maxillary incisors with talon cusps were found. When the central incisors were involved, 32 of the 35 (91.4%) underlying permanent successors were not found to be associated with any odontogenic abnormalities. When the lateral incisors were involved, however, 18 of the 23 cases (78.3%) showed odontogenic abnormalities, 14 of which were associated with supernumerary teeth.Conclusions. The present study shows that, when there is a talon cusp on a primary maxillary lateral incisor, a high proportion of the underlying permanent successors can be expected to exhibit odontogenic abnormalities.

Caries Research, 2006

Objectives: To compare the prevalence and severity of developmental defects of enamel (DDE) among... more Objectives: To compare the prevalence and severity of developmental defects of enamel (DDE) among subjects whose maxillary incisors developed during periods with different concentrations of fluoride in the public water supply. Methods: Standardized intra-oral photographs of random samples of 12-year-old children were collected in 1983, 1991 and 2001 (n = 1,990) in Hong Kong and assessed for DDE by a trained masked examiner. The fluoride concentrations in the public water supply at the times when the enamel on their maxillary incisors developed were 1.0, 0.7 and 0.5 ppm, respectively. Results:The mouth prevalence of DDE for these children (based on the maxillary incisors) were 92.1, 55.8 and 35.2% in the years 1983, 1991 and 2001, respectively (p < 0.001). Most of these children were affected by diffuse opacities (89.3% in 1983, 48.5% in 1991 and 32.4% in 2001, p < 0.001). Marked differences in the mean number of teeth affected by DDE (p < 0.001) and in the maximum extent of DDE (p ≦ 0.002) between 1983, 1991 and 2001 were also observed. Conclusions: A decrease in the prevalence and severity of DDE among the maxillary incisor teeth of the children corresponded to the reductions in the concentration of fluoride in the water during the time of enamel development.

Community Dentistry and Oral Epidemiology, Dec 1, 2005

To evaluate the validity and reliability of photographic examinations for developmental defects o... more To evaluate the validity and reliability of photographic examinations for developmental defects of enamel (DDE) in maxillary and mandibular incisors and canines using a standardized process. The anterior teeth of 257 children were examined &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;wet&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;, both clinically and photographically for DDE, using the modified Federation Dentaire Internationale (FDI) (DDE) Index. A series of five standardized photographs were taken for each child: a frontal view perpendicular to the four incisors; two lateral views, each showing the lateral incisors and canines on each side of the dental arch; and the superior and inferior views, retaking of the frontal view with the camera held at approximately 30 degrees above and below the horizontal plane. The photographs taken for each child were viewed as three different sets; the &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;five-view&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; (frontal, two lateral views plus superior and inferior views), &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;three-view&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; (frontal and two lateral views), and &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;one-view&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; (frontal view only) slide sets. Using &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;one view&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; slides, 91.7% of teeth could be examined photographically. Whereas using multiple views 99.9% of teeth could be assessed. At the subject level, agreements between clinical diagnoses (gold standard) and photographic examinations were substantial to almost perfect (k = 0.73-0.86). At the tooth level, agreement was best for incisors (k = 0.71 or higher). The intra-examiner reproducibility was high for the photographic assessments at both subject and tooth levels (k = 0.71-0.95). Multiple-view photographic slides of &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;five-view&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; and &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;three-view&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; are valid and reliable for assessing DDE on the 12 anterior teeth, while a &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;one-view&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; (frontal) was acceptable to study only the incisors.

Journal of Clinical Pediatric Dentistry, Jul 1, 2006

Talon cusp in the primary dentition: literature review and report of three rare cases

Caries Research, 2011

Objectives: To assess the impact of early childhood caries (ECC) on the quality of life in a popu... more Objectives: To assess the impact of early childhood caries (ECC) on the quality of life in a population of preschool children and their families in Hong Kong. Methods: A random sample of 1,296 Chinese preschool children participated in the survey and were subjected to an oral examination for their ECC status by 2 trained examiners. The parents were asked to respond to the Early Childhood Oral Health Impact Scale (ECOHIS) and an extra set of questions concerning their sociodemographic background. Results:The final data analysis included 1,261 children with a mean (±SD) age of 3.9 ± 0.66 years. The prevalence figures for ECC and severe ECC were 19.9 and 15.2%, respectively. Decayed teeth were found in 34.3% of the children while only 5.2% had filled teeth. The mean (±SD) dmft in this group of children was 1.5 ± 2.98. Higher ECOHIS scores were found in parents with lower education or income level, or with children who were born in mainland China (p < 0.05), or with children who had decayed, missing, or filled teeth (p < 0.001). In multiple regression analyses, decayed teeth and filled teeth in primary dentition were the better predictors (p < 0.001) of the ECOHIS score among the various parent and child characteristics collected in this survey. Conclusions: The findings of this study showed that parents of young children with dental caries experience perceived that both the children and other family members had poorer quality of life.

BMC Oral Health, 2019

Background Dental age estimation can assist in the identification of victims following natural di... more Background Dental age estimation can assist in the identification of victims following natural disasters and it can also help to solve birth date disputes in individuals involved in criminal activities. A reference dataset (RDS) has been developed from the dental development of 2306 subjects of southern Han Chinese origin and subsequently validated. This study aimed to test the applicability of the southern Han Chinese dental maturation RDS on three distinct East Asian population groups. Methods A total of 953 dental panoramic radiographs of subjects aged 2 to 24 years were obtained from Philippines, Thailand and Japan. The staging of dental development was conducted according to Anglo-Canadian classification system. The dental age (DA) was calculated using six methods; one un-weighted average and five weighted average (n-tds, sd-tds, se-tds, 1/sd-tds, 1/se-tds) methods based on the scores of the southern Han Chinese RDS. Statistical significance was set at p

Caries Research, 2003

Objective: To investigate the relationship between the presence of demarcated opacities and hypop... more Objective: To investigate the relationship between the presence of demarcated opacities and hypoplasia on permanent teeth and the caries status of the primary predecessor teeth in a cohort of Chinese children. Methods: The study sample consisted of 250 children living in a non-fluoridated area in Southern China whose caries status of primary teeth at the age of 3-6 years had been recorded annually in a previous study. A follow-up examination of their permanent teeth was conducted when they were about 12 years old. The presence of enamel defects was determined by consensus of 2 dentists according to the modified DDE index. Results: 56.8% of the 250 children examined had demarcated opacities, while 10.8% of them had hypoplasia. Demarcated opacities and hypoplasia were found in 5.8 and 1.3% of the teeth examined, respectively. A higher prevalence of demarcated opacities was found in those permanent teeth of which their primary predecessor teeth had caries than in those without (7.5 vs. 3.8%, p ! 0.001). A similar finding was obtained for the prevalence of hypoplasia (1.9 vs. 0.4%, p ! 0.001). Conclusion: There was an association between caries in primary teeth and the presence of demarcated opacities and hypoplasia in their permanent successors.

This is the first paper in a series that will review the role of formocresol and alternative pulp... more This is the first paper in a series that will review the role of formocresol and alternative pulp therapy medicaments for primary teeth in paediatric dentistry.

Journal of Dentistry

To determine, using eye-tracking technology, what children notice the most when they look at the ... more To determine, using eye-tracking technology, what children notice the most when they look at the dentist. A total of 41 children viewed 10 images of dentists of different genders and ethnicities, and wearing different attires, on a computer screen. Due to calibration issues with the eye tracking equipment, data from one child was excluded thus resulting in a final sample of 40 children (21 females; 19 males). Participants were aged 4-12 years. A Tobii X2-60 eye-tracking camera was used, which follows the location of participants' gaze as they look at images on a screen. Areas of interest (AOI's) were pre-defined on each image (e.g. eyes, mouth, shirt). Other images were displayed between dentist images with no consecutive dentist images displayed. Number of participants to fixate and mean length of fixation for each AOI were measured. Visual assessment illustrated that the dentist's face had the highest concentration of fixations, followed by attire. The circum-oral area has significantly more fixations than the eyes. The number of fixations and the mean length of fixation were both longer for the face than for the attire, and for the circum-oral area compared to the eyes. Distractors such as pens and ties exhibited more and longer fixations compared to images without distractors. Children fixated most on the dentist's face particularly the circum-oral area, followed by attire. Distractors were able to draw the children's gaze. Importantly, eye-tracking was an effective tool in assessing where children look on dentists' images. This research will provide an understanding of where children focus when they look at a dentist. This has not previously been known and will allow dentists to modify how they present themselves and interact with child patients.

BMC medical imaging, Apr 27, 2018

The accuracy of estimated age should depend on the reference data sets (RDS) from which the matur... more The accuracy of estimated age should depend on the reference data sets (RDS) from which the maturity scores or Ages of Attainment (AoA) were obtained. This study aimed to test the accuracy of age estimation from three different population specific dental reference datasets (RDS). Two hundred and sixty six dental panoramic radiographs of subjects belonging to southern Chinese ethnicity were scored and dental age (DA) was estimated from three reference datasets: French-Canadian, United Kingdom (UK) Caucasian and southern Chinese. Statistical significance was set at p < 0.05 and for each method, the difference between the chronological age (CA) and dental age (CA-DA) was calculated using paired t-tests. In addition, Chi-square tests were performed to evaluate the accuracy of the age estimates within specific time interval from CA. The estimated age difference (CA-DA) using the French Canadian RDS was - 0.62 years for males and - 0.36 years for females. For the UK Caucasian RDS, the ...

Journal of investigative and clinical dentistry, Jan 4, 2018

The aim of the present study was to assess risks prior to third molar removal. A 2-D panoramic ra... more The aim of the present study was to assess risks prior to third molar removal. A 2-D panoramic radiograph or a 3-D cone-beam computed tomography (CBCT) scan can be used to visualize the proximity of the third molar to the mandibular canal. We aimed to correlate panoramic indicators of risk with the incidence of contact between these two structures on CBCT scans. Patients were selected from a Western Australian population if they had a panoramic radiograph that illustrated signs of risk of inferior alveolar nerve injury and had a CBCT scan on file. Statistically-significant relationships between the relative position and distance between the mandibular canal and third molar were investigated using χ -test and Fisher's exact test in Stata version 13. Within the Western Australian sample (N = 100), of six possible panoramic indicators of risk, two were significantly associated with contact between the tooth and mandibular canal on CBCT: (a) interruption of the radiographic white li...