Dentigerous cyst formation following trauma to the primary incisors: A case report.

Although usually considered to be of developmental origin, dentigerous cysts (DCs) have been reported to form in response to chronic periapical inflammation associated with primary teeth that have necrotic, infected pulps. This article describes the management of a DC associated with tooth 21 in a seven-year-old Caucasian child with a history of multiple TDIs to the primary maxillary incisors. Chronic periapical inflammation associated with a necrotic pulp in tooth 61 was identified as the likely cause of the lesion. Initial conservative management involved marsupialization of the lesion by extracting the necrotic tooth 61. Following significant decompression of the cyst, surgical enucleation was carried out under general anaesthesia and an orthodontic attachment was bonded to the crown of the unerupted tooth 21 to facilitate traction. Histopathological assessment of the enucleated tissue confirmed it to be a DC. Two years after the initial presentation, teeth 21 and 22 had erupted into the oral cavity, improving patient aesthetics. However, the root of tooth 22 was transposed with the crown of the unerupted tooth 23. This case highlights the undesirable sequelae that may occur following delayed and inappropriate management of TDIs.

Tooth eruption and obesity in 12-year-old children.

BACKGROUND/PURPOSE: There is a need to comprehensively investigate the relationship between tooth eruption and obesity. The study aimed to investigate the relationship between erupted permanent tooth number and obesity among 12-year-old children in a population-based study. MATERIALS AND METHODS: A random sample of 806 12-year-old schoolchildren in Hong Kong was recruited. Oral examinations were conducted and the eruption status of the permanent teeth was assessed. Body height, body weight, waist circumference (WC), hip circumference, and triceps skinfold thickness (TRSKF) were measured to assess the adiposity statuses [weight-height ratio (W/H) and body mass index (BMI) for general obesity; WC and waist-hip ratio (WHR) for central obesity; and TRSKF for peripheral obesity]. The relationships between erupted permanent tooth number and adiposity statuses were examined in bivariate analysis and analysis of covariance. RESULTS: The response rate was 82.9% (n = 668/806). Three hundred and forty-six (50.9%) children had 28 teeth erupted. Second molars had the highest rate of noneruption (17.5-35.8%). The mean number and standard deviation (SD) of erupted permanent tooth were 26.4 (2.4). The mean value and SD were 31.1 (6.3) for W/H, 19.8 (3.7) for BMI, 70.4 (9.4) for WC, 0.82 (0.06) for WHR, and 11.8 (4.5) for TRSKF, respectively. After accounting for sociodemographic factors, analysis of covariance identified that W/H, BMI, WC, and WHR were positively associated with the number of erupted permanent teeth (P < 0.01). CONCLUSION: Erupted permanent tooth number was positively associated with obesity (general and central) among a population-based sample of 12-year-old children in Hong Kong.

Northern Chinese dental ages estimated from southern Chinese reference datasets closely correlate with chronological age.

While northern and southern Chinese are genetically correlated, there exists notable environmental differences in their living conditions. This study aimed to evaluate validity of the southern Chinese reference dataset for dental age estimation applied to northern Chinese. Dental panoramic tomographs of 437 northern Chinese aged 3 to 21 years were analysed. All the left maxillary and mandibular permanent teeth plus the 2 third molars on the right side were scored based on Demirjian's classification of tooth development stages. Mean and standard error of dental age were obtained for each tooth development stage, followed by random effect meta-analysis for mean dental age estimation. Validity of the method was examined through measures of agreement (95% limits of agreement, standard error of measurement, and Lin's concordance correlation coefficient) and measure of reliability (Intraclass correlation coefficient). On average, the estimated dental age overestimated chronological age by only around 1 month in both females and males. The Intraclass correlation coefficient values were 0.99 for both sexes, suggesting excellent reliability of the method. Reference dataset for dental age estimation developed on the basis of southern Chinese was applicable for use among the northern Chinese.

Longitudinal changes in developmental defects of enamel.

OBJECTIVES: Epidemiological studies on developmental defects of enamel (DDE) have focused on its potential contributory factors and prevalence while there is limited evidence on the longitudinal changes in the epidemiological profile of DDE. Thus, the objective of this longitudinal study was to investigate whether any type of DDE changes with time. METHODS: A total of 668 participants were initially recruited in 2010, and 432 participants were successfully followed up and examined for DDE both at the age of 12 in 2010 and 15 in 2013. The central incisor, lateral incisor and first molar in each quadrant were chosen as index teeth and were examined 'wet' by two trained and calibrated examiners using the modified FDI (DDE) Index. RESULTS: The mouth prevalence and tooth prevalence of 'any defect' showed a significant decrease from 2010 to 2013 (P < 0.001). This was predominantly due to the decrease in diffuse opacities (P < 0.001). Significant difference in the distribution of the extent of DDE was also found for diffuse opacities at both the participant and tooth levels irrespective of the types of tooth (P < 0.0001). Median extent score for diffuse opacities in 2013 was lower than those in 2010 at both participant and tooth level irrespective of the types of tooth (P < 0.001). CONCLUSIONS: Diffuse opacities, in terms of prevalence and severity, did fade out over time. The observed overall change in DDE was due to the dominating effect of diffuse opacities over demarcated opacities and hypoplasia.

Adjunctive application of chlorhexidine and ethanol-wet bonding on durability of bonds to sound and caries-affected dentine.

OBJECTIVES: To examine the effect of adjunctive application of chlorhexidine (CHX) and ethanol-wet bonding (EWB) on bond durability and nanoleakage of hydrophobic adhesive to sound (SD) and caries-affected dentine (CAD). METHODS: Dentine surfaces of molars were etched after caries removal and randomly allocated to four groups (n=12). In Groups 1 and 2, dentine surfaces were saturated with either 2 ml of 100% ethanol or 2 ml of ethanol with 2% CHX for 60s. In Groups 3 and 4, dentine surfaces were saturated with either 15 µL of distilled water or 15 µL of distilled water with 2% CHX for 60s. Two coats of primer, followed by neat resin were applied and light-cured for 40s. Resin composite build-ups were placed and bonded specimens were sectioned for bond strength testing after 24 h and 12 months' storage in artificial saliva. Bond strength data were analyzed using 3-way ANOVA and SNK tests. Interfacial nanoleakage was evaluated after 24 h and 12 months using a field-emission scanning electron microscopy and data were analyzed using Kruskal-Wallis test. RESULTS: Significant differences were observed for the three factors: "substrate" (p<0.001), "rewetting agents" (p<0.001) and "time" (p<0.001) on bond strength. Incorporation of 2% CHX to EWB preserved bond strength to SD and CAD and reduced interfacial nanoleakage after 12 months. Incorporation of 2% CHX to WWB also preserved bond strength to SD after ageing. CONCLUSIONS: Incorporation of chlorhexidine to ethanol-wet bonding has an interaction effect on preservation of bond durability to sound and caries-affected dentine. CLINICAL SIGNIFICANCE: Incorporation of chlorhexidine to ethanol-wet bonding with hydrophobic adhesive enhances the success rate of aesthetic bonded restorations.

Effect of chlorhexidine and ethanol-wet bonding with a hydrophobic adhesive to intraradicular dentine.

PURPOSE: To evaluate the effect of adjunctive application of ethanol-wet bonding and chlorhexidine (CHX) with a hydrophobic adhesive on bond durability of fibre posts to intraradicular dentine. METHODS: Ninety-six extracted human teeth with a single root and root canal were prepared for post placement after endodontic treatment. The teeth were randomly divided into four groups (n=24) after etching and rinsing for rewetting: Group 1: water-wet bonding, Group 2: water-wet bonding with CHX, Group 3: ethanol-wet bonding and Group 4: ethanol-wet bonding with CHX. Teeth in Groups 1 and 2 were treated with either distilled water or distilled water with 2% CHX for 60 s; while teeth in Groups 3 and 4 were treated with either 100% ethanol or 100% ethanol with 2% CHX. Two coats of primer, followed by neat resin were applied and light-cured for 40 s. Fibre posts were luted to bonded root dentine using dual-cure resin cement. Bonded roots were subjected to push-out bond strength testing and interfacial nanoleakage evaluation after 24 h, 6 and 12 months of storage. Data were analyzed using 3-way ANOVA (rewetting solutions, time and post space regions) and SNK tests. RESULTS: Groups 3 and 4 showed significantly (p<0.05) higher bond strengths and lower nanoleakage than Groups 1 and 2 after 12 months of ageing. Addition of 2% chlorhexidine to ethanol-wet bonding with a hydrophobic adhesive did not further improve the bonding of a fibre post to intraradicular dentine, when compared to ethanol-wet bonding alone after 12 months of ageing. CLINICAL SIGNIFICANCE: Ethanol-wet bonding with a hydrophobic adhesive alone could improve the bond durability of fibre post to intraradicular dentine and therefore would increase the success rate of post and core restorations of endodontically treated teeth.

Oral manifestations of Noonan syndrome: review of the literature and a report of four cases.

Noonan syndrome (NS) was described by Noonan and Ehmke as a multi-system disorder, which is typically evident at birth. The incidence of this syndrome is estimated to be one per 2500 to one per 1000 and affects both genders. While the clinical manifestations of NS have been well documented, the oral manifestations have not been extensively discussed. The purpose of the present article is to (a) review the oral manifestations of NS reported in the literature, and (b) describe four cases (three females and one male) of NS, who presented with short stature, cardiac problems and various oral findings. Based on these cases, we conclude that many oral anomalies may have possible relationships with NS, which require multidisciplinary treatment planning and timely management. The importance of oral findings in NS has largely gone unnoticed and it is essential to consider oral manifestations as scoring criteria in the diagnosis of NS.

Comparison of the remineralizing potential of child formula dentifrices.

BACKGROUND: Although child formula fluoridated dentifrices can be used safely by young children their remineralizing capability remains questionable. AIMS: To evaluate the remineralizing potential of child formula dentifrices on primary teeth. DESIGN: In vitro single-section technique utilizing a 7 days pH-cycling model. METHODS: Primary teeth were placed in demineralizing solution for 96 h to produce artificial carious lesions 100 µm deep, and then cut longitudinally into 50 sections 100-150 µm thick and randomly assigned to five groups. Sections in Groups A to D were treated with dentifrices containing 500 ppm AmF, 500 ppm MFP, 500 ppm MFP and xylitol, or 500 ppm NaF, respectively. Group E sections were treated with a nonfluoridated dentifrice. OUTCOME MEASUREMENTS: Lesions were evaluated using polarized light microscopy and microradiography. RESULTS: Group D (500 ppm NaF) sections exhibited a significant decrease in lesion depth, whereas those in Group E (nonF) showed a significant increase in depth (P<0.05, paired t-test). Decrease in lesion progression was observed in Groups A, B and C. CONCLUSIONS: The 500 ppm NaF dentifrice demonstrated remineralization of carious lesions by virtue of a significant decrease in lesion depth; whereas dentifrices that contained AmF, MFP and MFP with xylitol decelerated the progression of demineralization.

Effect of surface preparation on bond strength of resin luting cements to dentin.

This study examined the effects of using two different burs for dentin surface preparation on the microtensile bond strength (microTBS) of three resin luting cements. Flat, deep dentin surfaces from 45 extracted human third molars were divided into three groups (n = 15) according to bur type: (i) diamond bur and (ii) tungsten carbide bur. The controls were abraded with #600-grit SiC paper. Both burs operated in a high-speed handpiece under water-cooling. Composite blocks were luted onto the dentin using one of three cements: RelyX ARC (ARC, 3M ESPE), Panavia F2.0 (PF, Kuraray) and RelyX Unicem (UN, 3M ESPE) following the manufacturers' instructions. For ARC, the dentin surface was treated with 32% phosphoric acid. The bonded specimens were stored at 37 degrees C for 24 hours and sectioned into 0.9 x 0.9 mm beams for microTBS testing. The data were analyzed using the two-way ANOVA and Student-Newman-Keuls tests. Representative fractured beams from each group were prepared for fractographic analysis under SEM. Two-way ANOVA revealed that the effects of "dentin surface preparation" and "luting cement" were statistically significant (p < 0.001); however, the interaction of these two factors was not significant (p > 0.05). ARC showed no significant difference in microTBS among the three differently prepared dentin surfaces. The microTBS of PF and UN was significantly lower when bonding to dentin prepared with a diamond bur (p < 0.05), compared to the control. For Panavia F2.0, higher bond strengths were achieved on the dentin surface prepared with a tungsten carbide bur. Proper bur selection is essential to optimizing the dentin adhesion of self-etch resin luting cements.

Effect of acid etching time on bond strength of an etch-and-rinse adhesive to primary tooth dentine affected by amelogenesis imperfecta.

BACKGROUND: Dentine affected by amelogenesis imperfecta (AI) is histologically altered following loss of the hypoplastic enamel and becomes hypermineralized, which would make bonding less predictable. AIM: This study examined the effect of etching time on the microtensile bond strength (microTBS) to AI-affected primary dentine. DESIGN: Flat coronal dentine surface was obtained from extracted AI-affected and noncarious primary molars. Teeth were etched either for 15 or for 30 s using 34% phosphoric acid. Prime & Bond NT (Dentsply De Trey), an etch-and-rinse adhesive, was applied to dentine surfaces, air-dried and light-cured, followed by composite build-ups. The bonded teeth were sectioned into beams of 0.8 mm(2) and stressed to failure under tension. Representative fractured beams from each group were examined under scanning electron microscopy. RESULTS: The extended etching time had an adverse effect on the microTBS for the normal dentine, while no significant difference was found for AI-affected dentine. When the AI-affected dentine was etched for 30 s, the fracture occurred in the demineralized dentine at the base of the hybrid layer. CONCLUSION: Bonding to AI-affected dentine compromised the bonding of the etch-and-rinse adhesive. The bonding could not be improved by increasing etching time.

The relationship between a primary maxillary incisor with a talon cusp and the permanent successor: a study of 57 cases.

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.

A comparison between a conventional optical method and image-analysis for measuring the unimpeded eruption rate of the rat mandibular incisor.

The impeded/unimpeded eruption rates of the rat incisor have been much studied. The most commonly used optical microscopic method, which has inherent weaknesses, was compared here with an image-analysis method to measure the eruption rate of the mandibular incisor. The study also evaluated the incisal edge as a reference point for the measurement of the unimpeded eruption rate, and the frequency of shortening the mandibular incisor. The image-analysis method was found to be a simple and reliable technique that could replace the optical method. There was no significant difference between the data from the two methods; their kappa coefficients were similar at the 0.99 level. It was concluded that shortening the incisor in the measurement of the unimpeded eruption rate should be done at least every 48 h, and that the incisal edge of the shortened incisor can be used as the reference point for that measurement.