Utilising surface-level data to explore surface, tooth, individual and family influence on the aetiology of hypomineralised second primary molars.

OBJECTIVES: Hypomineralised second primary molars (HSPM) are common developmental enamel defects. The aims of this study were to use surface-level data to explore the clustering of HSPM at four levels (family, child, tooth, surface). METHODS: This study of 172 twin pairs was nested within the Peri/postnatal Epigenetic Twin Study. HSPM was measured by standardised oral examinations at age 6 years. Multilevel logistic regression models were fitted to assess the correlation structure of surface level data and variation in HSPM. The associations between surface level risk factors and HSPM were then explored using the multilevel logistic regression model using the best fitting correlation structure. RESULTS: The prevalence of HSPM was 68 (19.8%) children, with a total of 141 (10.3%) teeth and 264 tooth surfaces (6.3%) affected. Multilevel models revealed that a hierarchical structure accounting for correlation at the family, child and tooth level best accounted for the variation in HSPM. The estimated variances from the best fitting model (Model 3) were largest at the family level (12.27, 95% CI 6.68, 22.51) compared with 5.23 at the child level and 1.93 at the tooth level. Application of regression analysis utilising this three-level correlation structure identified tooth/surface level factors in addition to the previously identified familial and individual risk factors for HSPM. CONCLUSION: In addition to familial (environmental and genetic) and unique child-level factors, the aetiology of HSPM is likely to be influenced by local tooth-level factors.

A twin study of body mass index and dental caries in childhood.

Sub-optimal nutrition and dental caries are both common with significant short and long-term implications for child health and development. We applied twin statistical methods to explore the relationship between body mass index (BMI) and dental caries. We measured BMI at 18 months and six years of age and cumulative dental caries experience at six years in 344 twin children. Dental caries in primary teeth was categorised into 'any' or 'advanced' and BMI was analysed as both a continuous and categorical variable. Statistical analyses included multiple logistic regression using generalized estimating equations and within/between-pair analyses. There was no association between BMI and 'any' dental caries experience at either time-point, neither overall nor in within/between pair analyses. However, 'advanced' dental caries at six years was associated with a within-pair difference in BMI of -0.55 kg/m2 (95% CI -1.00, -0.11, p = 0.015). A within-pair increase of 1 kg/m2 in BMI was associated with a lower within-pair risk of advanced dental caries (OR 0.68, 95% CI 0.52, 0.90, p = 0.007). These findings reveal a possible causal relationship between lower BMI and dental caries. As dental outcomes were only measured at one time point, the direction of this potentially causal relationship is unclear.

Getting ahead of the oral health game: it starts before we're born?

Dental caries is one of the most common chronic diseases affecting individuals of all ages. Caries in the primary dentition is one of the main risk factors for caries in the permanent dentition. Preventing the development of the first carious lesion is fundamental not only to long term health and wellbeing but to reducing the burden of this disease on individuals, families and the community. Described as the developmental origins of health and disease, events from the prenatal period are increasingly recognised as having a significant impact on later health outcomes. While social and behavioural factors from this period have long been linked with oral health, emerging evidence of the influence of epigenetics and early life programming of microbiome and host response suggests that the prenatal period provides a timely opportunity for preventive interventions. Pregnancy is an ideal time to focus on health promoting activities as most women have regular interaction with health care professionals who can target risk factors before the onset of disease. This paper summarizes contemporary understanding of the role of pre- and perinatal factors on child oral health and describes how this evidence might be used by all health professionals to ensure infants start life ahead in the oral health game.

Etiology of Hypomineralized Second Primary Molars: A Prospective Twin Study.

The etiology of hypomineralized second primary molars (HSPM) is unclear, but genetic and environmental factors have been proposed. The aim of this study was to investigate the relative contribution of genes and environment to the etiology of HSPM and to identify potential environmental risk factors in a longitudinal twin cohort. Children from twin pregnancies ( N = 250) were recruited antenatally, and detailed demographic, health, and phenotypic data were collected at recruitment, 24- and 36-wk gestation, birth, and 18 mo of age. 25-Hydroxyvitamin D was quantified for mothers at 28-wk gestation and infants at birth. Dental examinations were conducted on the twins at 6 y of age to determine the presence, severity, and extent of HSPM per standardized criteria. To investigate associations of environmental risk factors with HSPM, multiple logistic regression models were fitted with generalized estimating equations to adjust for twin correlation. Within- and between-pair analyses were performed for unshared continuous variables: birthweight and birth 25-hydroxyvitamin D. Twin-twin concordance for monozygotic (MZ) and dizygotic (DZ) pairs was calculated and compared after adjusting for identified risk factors. A total of 344 twins underwent the 6-y-old dental assessment; HSPM occurred in 68 (19.8%). After adjusting for potential confounders, vitamin D levels at birth, infantile eczema, dizygosity, in vitro fertilization, socioeconomic position, and maternal smoking beyond the first trimester of pregnancy demonstrated the strongest associations with HSPM. Overall concordance for HSPM was 0.47 (95% CI, 0.32 to 0.62) with weak evidence ( P = 0.078) of higher concordance in MZ twins (0.63; 95% CI, 0.38 to 0.89) as compared with DZ twins (0.41; 95% CI, 0.24 to 0.58). After adjusting for known risk factors, there was no evidence ( P = 0.172) for an additive genetic influence. These findings suggest that shared and unshared environmental factors, such as maternal smoking later in pregnancy and infantile eczema, are important in the etiology of HSPM.

Molar incisor hypomineralization: a survey of members of the Australian and New Zealand Society of Paediatric Dentistry.

BACKGROUND: Worldwide, molar incisor hypomineralization (MIH) affects a substantial number of children and impacts greatly on treatment need and dental anxiety, yet there is little information regarding its prevalence, aetiology, presentation and management. The aims of this survey were to assess awareness and perceptions of the Australian paediatric dental community concerning MIH, and to describe current treatment strategies. METHODS: A questionnaire, based upon a previous European study, was sent to all Australian members of the Australian and New Zealand Society of Paediatric Dentistry. The questionnaire sought information on clinical experience of MIH, knowledge of prevalence, aetiology and contemporary management strategies for MIH. RESULTS: One hundred and thirty useable responses were received (58.8 per cent response rate) of which 36 were paediatric dentists, 6 paediatric dentistry postgraduate students, 59 general dentists, 14 dental therapists and 14 specialists in other fields. Most (98.5 per cent) respondents were familiar with MIH and encountered it in their practice. The majority (73.1 per cent) estimated that MIH occurred in between 5 to 25 per cent of their clinical practice and almost all (96.9 per cent) considered it to be a clinical problem. Only 16.9 per cent of respondents were aware of existing prevalence data and 96.9 per cent valued investigating the prevalence of MIH. No consensus existed regarding the aetiology of MIH or its restorative management. Paediatric dentists used preformed crowns significantly more than non-specialists, however glass ionomer cements were popular with all groups. CONCLUSIONS: MIH is a well recognized and widely encountered clinical condition. MIH presents several clinical problems and is worthy of further investigation. Currently, no consistent clinical management strategies are utilized.

Parental knowledge, beliefs and behaviours for oral health of toddlers residing in rural Victoria.

BACKGROUND: Little is known about the oral health of children under the age of four years. The determinants of early childhood caries (ECC) in this young age group are also not well understood despite a growing recognition that early interventions may deliver the greatest benefits. The aim of this study was to examine the oral health-related knowledge, attitudes and reported behaviours of parents of children aged 12-24 months living in rural areas of Victoria, Australia. METHODS: A robust theoretical model was utilized to identify oral health-related behaviours and their antecedent and reinforcing conditions within the context of this specific population group. Two hundred and ninety-four parent/child dyads were recruited through their maternal and child health nurses as part of a larger intervention trial. Parents completed a self-report questionnaire. RESULTS: Knowledge regarding risk and protective factors amongst parents was variable and sometimes at odds with contemporary evidence. Knowledge of the role of early infection with S. mutans was very low, with high levels of behaviours that may promote early transmission reported. Tooth cleaning was reported by most parents at least sometimes, however a large proportion lacked confidence and this was significantly related to the frequency of the cleaning. Parents were confused about the fluoride status of their water supplies. Most parents believed fluoride toothpaste reduced the risk of ECC but did not know whether it should be used with toddlers. CONCLUSIONS: The results of this study have implications for efforts to prevent dental decay in this very young age group. Health care professionals other than dentists need support to provide information and promote confidence with regard to optimal fluoride exposure. Attention should also be given to the contribution of early contact with particular bacteria in oral health education and promotion programmes.

On the structure-property relationship of sound and hypomineralized enamel.

Developmental defects in dental enamel pose significant clinical challenges which have highlighted our limited understanding of the structure and properties of this tissue. In this study, we first investigated the contact-size dependence of the physical properties of sound and hypomineralized enamel, and then examined the microstructure to establish a structural basis for their differing properties. Depth-sensing indentation tests were carried out over a wide range of peak loads in a direction perpendicular to the enamel prisms. Hypomineralized enamel demonstrated stronger penetration dependence for measured hardness and elastic modulus than sound enamel. The microstructure of sound and hypomineralized enamel was observed using field emission scanning electron microscopy and transmission electron microscopy with support of a focused ion beam milling system. Images of sound enamel showed barely distinguishable sheath regions with minimal organic presence. In contrast, hypomineralized enamel showed thicker sheath structures surrounding the prisms and higher levels of organic content within both the prisms and the sheath regions. It is argued that the higher organic content within prism structure was responsible for an initial lower hardness and elastic modulus of hypomineralized enamel under low-load indentation. As the indentation depth increased, the thicker organic-rich sheath regions played a more important role in reducing the mechanical properties of the hypomineralized enamel. On the basis of Spears finite element model [Spears IR. A three-dimensional finite element model of prismatic enamel: a re-appraisal of the data on the Young's modulus of enamel. J Dental Res 1997; 76(10):1690-97], elastic moduli of sound and hypomineralized enamel were predicted, which matched experimental results.

A qualitative study exploring barriers to a model of shared care for pre-school children's oral health.

OBJECTIVE: To explore the oral health beliefs and practices of primary health care professionals which may act as barriers to the development of a model of shared care for the oral health of pre-school children. DESIGN: Qualitative focus group discussions and semi-structured interviews. SETTING: Four rural local government areas in Victoria, Australia, 2003. SUBJECTS: maternal and child health nurses, general medical practitioners, dental professionals and paediatricians working in the four local government areas. DATA COLLECTION: discipline specific focus groups and semi-structured interviews. DATA ANALYSIS: transcription, coding, clustering and thematic analysis. RESULTS: Several strong themes emerged from the data. All participants agreed that dental caries is a significant health issue for young children and their families. Beliefs about the aetiology of dental caries and its prevention were variable and often simplistic focusing predominantly on diet. Dental professionals did not believe that they had a primary role in the oral health of pre-school aged children but that others particularly maternal and child health nurses did. However other health care professionals were not confident in assuming this role. CONCLUSIONS: This study has identified important barriers and possible strategies for the development of an integrated and shared approach to preventing dental caries in pre-school aged children. Clear and consistent oral health information and agreed roles and responsibilities need to be developed.

Mechanical properties and microstructure of hypomineralised enamel of permanent teeth.

Isolated enamel defects are commonly seen in first permanent molar teeth but there has been little work on the physical and morphological composition of affected molars. The aim of this study was to determine the mechanical and morphological properties of hypomineralised first permanent molar teeth, utilising the Ultra-Micro-Indentation System (UMIS) and scanning electron microscope, respectively. Further investigations using Energy Dispersive X-ray Spectrometery (EDS), Back Scatter Electron (BSE) Imaging, and X-ray diffraction were employed to attempt to determine the chemical composition, mineral content and crystalline structure of the hypomineralised tissue, respectively, of eight first permanent molars with severe enamel hypomineralisation. The hardness and modulus of elasticity were found to be statistically significantly lower (0.53+/-0.31 and 14.49+/-7.56 GPa, respectively) than normal enamel (3.66+/-0.75 and 75.57+/-9.98 GPa, respectively). Although the fractured surface of the hypomineralised enamel was significantly more disorganised and the relative mineral content was reduced by approximately 5% in comparison to sound enamel, the mineral phase and Ca/P ratio was similar in hypomineralised and sound enamel. The dramatic reduction in the mechanical properties of first permanent molar teeth has ramifications when clinicians are choosing restorative materials to restore the defects. The reason for the dramatic reduction in mechanical properties of hypomineralised first permanent molar teeth is at present unknown.

Gingival overgrowth in pediatric heart and heart-lung transplant recipients.

BACKGROUND: Gingival overgrowth is a recognized side effect of cyclosporine therapy with cosmetic and functional sequelae. This study examines the incidence and severity of gingival overgrowth in pediatric heart and heart-lung transplant recipients. METHODS: Thirty-one pediatric heart and heart-lung transplant recipients underwent a comprehensive dental evaluation. The severity of gingival overgrowth was scored by use of dental plaster casts. Parameters of dental hygiene in each patient included both a plaque index and a gingival inflammation index. The mean cyclosporine level and daily dose (mg/kg/day) at 3 and 12 months after transplantation and at latest follow-up were determined. RESULTS: The mean (+/- SD) patient age at transplantation was 10.5 (+/- 5.5) years, and the mean duration of posttransplantation follow-up was 3.2 (+/- 2.1) years. In all 30/31 (97%) of the cohort had some degree of overgrowth, with children aged less than 10 years at time of transplantation the most severely affected. By univariate analysis gingival overgrowth was inversely related to age at time of transplantation (r = -0.67, p < 0.001). With multiple regression analysis, only age at transplantation was significantly related to gingival overgrowth. CONCLUSIONS: Gingival overgrowth occurs in most pediatric heart and heart-lung transplant recipients treated with cyclosporine and is most severe in the younger patients. Attention to oral hygiene may improve gingival health parameters; however, the daily weight-adjusted dose of cyclosporine is not related to the severity of overgrowth.

Durability of restorations in primary molars.

Techniques used to restore carious primary molars have changed over the past decade as new adhesive materials have been developed. The most meaningful way of assessing the efficacy of a technique is by clinical trials. This article reviews the information concerning amalgam, composite and glass polyalkenoate (ionomer) cement as well as extracoronal restorations. Stainless steel/nickel chrome crowns provide the most durable restoration, often surviving until the tooth exfoliates. Class II amalgam restorations, whilst being prone to fracture, have been shown to survive about 3 years, a figure that improves with increasing age of the child and the use of local anaesthesia. Over the shorter term resin-based composites appear to be at least as durable as amalgam, particularly with respect to the maintenance of a good anatomical form. In contrast, when assessed at 6 years the failure rate of composite restorations is high, 62%, whereas the failure rate of amalgam restorations at 5 years is as low as 20%. Glass ionomer cements and cermets are alternative materials for use in the primary dentition. The reported success rate of 33% over 5 years for conventional glass ionomer cements is encouraging, however cermets appear to be less successful but have not been evaluated over the longer term. Glass ionomer cements provide a means of restoring primary molars with minimal amount of destruction of sound tooth tissue and reduced treatment time for the young patient, whilst the local fluoride release is also a potential advantage.(ABSTRACT TRUNCATED AT 250 WORDS)

Factors that influence the setting characteristics of encapsulated glass ionomer cements.

The slow rate of the setting reaction of glass ionomer cements (GICs) is one of the problems associated with their clinical use. The manufacturers of these materials suggest that increasing the mixing time will increase the rate of reaction and it was the purpose of this study to investigate the limits of this relationship. The method used to monitor the setting reaction with Differential Thermal Analysis (DTA). The results obtained using DTA were compared with those obtained using the ISO penetrometer method as defined in the ISO standard for water-based cements, ISO 9917:1991E. It was shown that increasing the mixing time of cements did not significantly reduce the setting time (P > 0.05). Under the conditions of the study it was only possible to measure a working time for the Chemfil II (and then only if it was mixed for less than 12 s). Storing the capsules at 4 degrees C did enable a working time to be measured using the DTA for all the materials, however these storage conditions also produced a significant increase in the setting time which would be undesirable to the clinician. The penetrometer method underestimated the duration of the setting reaction by up to 32% compared with the DTA method. However it was a quick and reproducible method of measuring setting time and as such may still be an appropriate method for use in the ISO standards.

A clinical comparison of a light cured glass ionomer sealant restoration with a composite sealant restoration.

OBJECTIVE: To compare the durability of a minimal composite sealant restoration (MCR) with that of a glass ionomer sealant restoration (GSR). METHODS: Under local anaesthesia, a MCR and a GSR were placed in the mouths of selected patients; allocation of restoration type was made randomly. All restorations were placed by one operator using standard procedures and were then assessed clinically at baseline and thereafter every 6 months. RESULTS: Fifty-eight patients, with a total of 66 pairs of restorations, were reviewed for up to 27 months. Assessment criteria were based upon the amount of sealant lost, the state of the pit restoration and the occurrence of caries. There were no cases of recurrent caries, and a total of only four pit restorations failed, three (4.5%) GSRs and one (1.5%) MCR. Three MCRs and seven GSRs required further additions of sealant. Survival analysis was carried out using the loss of more than a third of the sealant as the failed status. At this level, the MCRs had a significantly greater Median Survival Time (MST) (24.7 months) than the GSRs (20.7 months) (p < 0.05). Only seven (10.6%) of the MCRs lost more than a third of their sealant as compared with 17 (25.8%) of the GSRs. CONCLUSIONS: There was no significant difference in the durability of the MCR compared with the GSR in the treatment of occlusal caries. However, there was significantly better retention of the fissure sealant over the composite restoration than over the glass ionomer.

The use of cantilevered, adhesively retained bridges with enhanced rigidity.

Adhesively retained bridges replacing missing posterior teeth are reported to be less successful than those used to replace anterior teeth. This is due in part to the increased occlusal loading in the posterior region and inadequate rigidity of the retainers. This report describes the use of minimal preparation cast restorations incorporating an 'occlusal strut' to improve the rigidity of the retainers used to support pontics replacing upper premolars. The advantages of using intracoronal minimal preparations are discussed.

The use of a reinforced glass-ionomer cermet for the restoration of primary molars: a clinical trial.

The development of adhesive restorative materials has led to more conservative cavity design with greater reliance being placed upon the bond of a material with tooth tissue for retention of the restoration. Glass-ionomer cements may offer particular advantages but have yet to achieve the durability reported for amalgam. This study reports on the results of a 2.5-year prospective clinical trial comparing the durability of two glass-ionomer cements, a conventional material (Ketac Fil) and a metal reinforced cermet (Ketac Silver) in the restoration of Class II lesions in primary molars. Forty-six pairs of restorations were assessed in 37 children. The failure rate of Ketac Fil, 23%, was significantly lower than that of Ketac Silver, 41% (P < 0.05). The median survival time of the Ketac Fil restorations was significantly greater, 25.3 months, than that of the Ketac Silver restorations, 20.3 months (P < 0.05). These values may be an underestimate of the true longevity of both restoration types as many of the restorations survived intact at the censor date. Neither the age of the child nor the tooth restored influenced the durability of the restoration. The deterioration in both marginal integrity and anatomic form of the Ketac Silver restorations was significantly greater than the Ketac Fil restorations (P < 0.05). The durability of Ketac Silver was such that it cannot be recommended for use in restoring carious primary molars.

The implication of phenylketonuria on oral health.

PURPOSE: This study was performed to evaluate the oral health of children with PKU and to assess, in vitro, the erosive potential of 5 amino acid supplements commonly prescribed in the management of these children. METHODS: Forty children with phenylketonuria underwent a full dental examination and were compared with an age and sex matched control group. The erosive potential of the supplements was assessed by comparing their pH and titratable acidity to those of Coca Cola and orange juice. RESULTS: There was no significant difference between the affected and control groups in the level of dental caries, with over 75% of the children examined being caries free. However significantly more (33%) children with phenylketonuria exhibited signs of tooth wear compared with 24% of the controls (P < 0.05). While Coca Cola had the lowest pH (2.46), the titratable acidity of the flavoured supplements (92.86-126.8 mEq/l) was significantly higher than both their unflavored counterparts (4.18-14.0 mEq/l) and Coca Cola (38.56 mEq/l). CONCLUSIONS: Despite the potentially damaging nature of their diet, significantly less children with PKU had ever seen a dentist. Health professionals involved in the care of these patients should be aware of the implications of management and provide appropriate dental advice and referral.

Desensitization of the gag reflex in an adult with cerebral palsy: a case report.

Severe oral hypersensitivity and aversive oral behaviors present a significant barrier to dental treatment and compromise oral health status. Although several authors have addressed the reduction of oral hypersensitivity and aversive behaviors (such as gagging, retching, and vomiting) in the otherwise well dental patient, treatment for patients with severe disability has not been explored. The successful management of oral hypersensitivity and aversive behavior can have significant health benefits. These can be described via an outcomes paradigm as physical and social benefits for the patient, psychological benefits for the patient, carer, and practitioner, and organizational benefits for the institutions providing dental care and medical management. This paper summarizes the management of a severely disabled patient whose aversive behaviors were eliminated with non-invasive therapy techniques. Oral hygiene was facilitated and health benefits were identified across a number of domains following successful multi-disciplinary management.

The effect of glass ionomer cement on the surface hardness of resin based materials.

The potential interaction between resin-based materials and glass ionomer cements was investigated by comparing the hardness of the non-adjacent surface of two different resin materials when cured over the cements. Control specimens were made by curing the resin materials over an acrylic surface. Two glass ionomer cements were tested and neither were shown to cause a significant reduction in the surface hardness of either of the resin based materials. The 0.5 mm thick specimens of both resin based materials were significantly softer than the thicker specimens irrespective of the base material.

Glass ionomer cements: their application in children, Part 1.

Glass ionomer cements were first developed in the early 1970s in an attempt to combine the advantages of silicates and polycarboxylate cements. The two key features of this group of materials are their ability to bond chemically to enamel and dentine and their fluoride-releasing properties. This article reviews the clinical applications of glass ionomers in young patients and in particular to evaluate their use in prevention, bonding and restorations.

Hydrochloric acid/pumice microabrasion technique for the removal of enamel pigmentation.

Products for lightening teeth are appearing on the market with ever-increasing frequency. Heavy advertising, coupled with heightened public awareness and expectations of an aesthetically pleasing smile, have resulted in increased patient demand for treatment to improve all types of tooth discoloration. Although it is the role of the dental profession to provide the services demanded by the consumer, it is also our duty to be discerning and to re-assess continually the techniques we use, for both efficacy and safety. To do this, long-term follow up of clinical techniques is essential. This paper contains the clinical results of teeth treated over 4.5 years using the hydrochloric acid/pumice microabrasion technique to remove enamel opacities and pigmentation. The subject under discussion is that of enamel discoloration: intrinsic staining with its origins in dentine, such as that caused by the ingestion of tetracycline antibiotics during odontogenesis, is not amenable to this form of surface treatment.