Evaluation of Mineral Trioxide Aggregate and Biodentine as pulpotomy agents in immature first permanent molars with carious pulp exposure: A randomised clinical trial.

AIM: There is insufficient evidence on the outcome of pulpotomies in carious exposed young permanent molars with newer biomaterials. This study aimed to compare Mineral Trioxide Aggregate (MTA) and Biodentine as pulpotomy materials in carious exposed vital immature mandibular first permanent molars. MATERIALS AND METHODS: Study design: Sixty immature first mandibular permanent molars, with carious exposure were randomly assigned to an MTA or Biodentine group in a split-mouth design. After the amputation of the coronal pulp, the pulp stumps were covered with one of the study materials and coronal restorations placed. Blinded clinical and radiographic evaluations were performed at baseline. Following this there were evaluations at 6, 12 and 18 months where comparisons between and within the two groups were made. RESULTS: A high success was observed in both groups for all outcome measures for clinical success, with no significant difference between them. The mean survival time for the Biodentine and MTA groups was (17.8 and 18 months) with 95% confidence interval (17.4-18.2) and (18 .0-18.0) months respectively. Similarly, there were no significant differences between the Biodentine and MTA groups for radiographic success (P<0.001) with an increase in root length and increasing apical closure observed in both groups. CONCLUSIONS: Both materials were equally effective in the treatment of cariously exposed vital immature mandibular first permanent molars.

European Society of Endodontology position statement: Surgical extrusion, intentional replantation and tooth autotransplantation: European Society of Endodontology developed by.

This European Society of Endodontology (ESE) position statement on surgical extrusion, intentional replantation and tooth autotransplantation represents the consensus of an expert committee, convened by the ESE. A narrative review in the International Endodontic Journal (Plotino et al. 2020, international Endodontic Journal, 53, 1636-52) formed the basis for the position statement. The review provided detailed information on the background, clinical procedures and the outcome of surgical extrusion, intentional replantation and tooth autotransplantation techniques. The aim of the current statement is to summarize the best available evidence on these clinical techniques to provide appropriate clinical guidance to undergraduate and postgraduate students, dental practitioners, clinical teachers and researchers. The current position statement will be updated by the ESE periodically to reflect new evidence as it becomes available to provide the most current treatment guidance for clinical practice.

Rinsing with water for 1 min after milk formula increases plaque pH.

PURPOSE: Parents find it challenging to follow recommendations to brush young children after feeds at night despite the increase caries risk. This study compared three clinical recommendations (dilution, rinsing and wiping) on plaque pH after formula consumption. METHODS: Eighteen subjects were recruited. The five interventions with 2-week washout between visits included: Rinse with undiluted formula for 30 s (UF); rinse with 50% diluted formula for 30 s (DF); rinse with undiluted formula for 30 s, followed by rinsing with water for 1 minute (UF/R); rinse with undiluted formula for 30 s, followed by wiping (UF/W); rinse with 10% sucrose for 30 s as control (C). Plaque samples were collected at baseline, 2, 5, 10, 20 and 30 min after the intervention and pH measured using the plaque sampling method. RESULTS: UF/R resulted in significantly smaller pH drops at 5, 10 and 20 min compared to UF. It also resulted in higher minimum pH (UF/R: 6.34 ± 0.36 Vs UF: 6.06 ± 0.40, p = 0.02), smaller maximum pH drop (UF/R: 0.63 ± 0.35 Vs UF: 0.90 ± 0.49, p = 0.03), smaller sum of change of hydrogen ion concentration (UF/R: 9.22 × 10-7 ± 7.8 × 10-7 Vs UF: 2.30 × 10-6 ± 2.6 × 10-6, p = 0.04), and smaller area under the curve (UF/R: 7.70 ± 5.44 Vs UF: 13.44 ± 9.44, p = 0.02). DF and UF/W did not result in any significant pH change compared to UF. CONCLUSIONS: Of the three clinical recommendations, only rinsing with water for 1 min after undiluted formula reduced plaque acidogenicity. Teeth wiping with a moist cloth and 50% dilution of infant formula did not have an effect on plaque acidity.

Clinical procedures and outcome of surgical extrusion, intentional replantation and tooth autotransplantation - a narrative review.

Surgical extrusion is defined as the procedure in which the remaining tooth structure is repositioned at a more coronal/supragingival position in the same socket in which the tooth was located originally. Intentional replantation is defined as the deliberate extraction of a tooth and after evaluation of root surfaces, endodontic manipulation and repair, placement of the tooth back into its original position. Tooth autotransplantation is defined as the transplantation of an unerupted or erupted tooth in the same individual, from one site to another extraction site or a new surgically prepared socket. The advent of titanium implant rehabilitation has reduced the use of these treatments in day-by-day clinical practice; however, the re-emerging trend to conserve and preserve natural sound tissues has led to a rediscovery of these treatments. All three distinct surgical methods are closely related, as they act to treat teeth that cannot be predictably treated using other more conventional procedures in endodontics, periodontics and restorative dentistry. Furthermore, these procedures share the same treatment approach and include the atraumatic extraction of a tooth, visual inspection of the tooth/root and its subsequent replantation. The clinical procedures for surgical extrusion, intentional replantation and tooth autotransplantation treatment have undergone several changes in recent years, and currently, there are no clear clinical treatment protocols/guidelines available. The clinician should be aware of the outcome of these treatments. Hence, the aim of this narrative review is to provide the background, clinical procedures and outcomes of surgical extrusion, intentional replantation and tooth autotransplantation.

Revitalisation endodontic treatment of traumatised immature teeth: a prospective long-term clinical study.

PURPOSE: Continuation of root development following revitalisation endodontics (RET) has been shown to be unpredictable with lower success rates in traumatised teeth. This study reports the outcomes for RET in traumatised teeth over a review period of 4 years. METHODS: A prospective uncontrolled study, where RET was performed on traumatised upper immature anterior teeth with necrotic pulps in 15 children (mean age = 8.3 years), was conducted. Patients were reviewed at 3, 9, 12, 24, and 48 months, where clinical and radiographic assessments were performed. At the last review appointment, patients and parents answered questions assessing their perception and acceptance of tooth colour change over time. McNemar's Exact test and linear mixed model assessment were used to assess changes in pulpal electrical response and radiographic evidence of continuation of root development over time, respectively. RESULTS: There was 83.3% healing with no significant changes in EPT responses, and no significant changes in root lengths, while significant changes in root widths (p < 0.05) and root apex widths (p < 0.001) were found over time. Twenty-five percent of patients and 33% of parents felt that there were changes in tooth colour following RET over time. CONCLUSION: Within the limitations of this study, traumatised teeth treated using RET showed no significant root lengthening, however, acceptable periapical healing, slow thickening of root dentinal walls, and rapid development of apical closure were evident over a period of 43 months. Using Portland cement and omitting minocycline, did not eliminate crown colour change following RET.

Best clinical practice guidance for prescribing dental radiographs in children and adolescents: an EAPD policy document.

BACKGROUND: The European Academy of Paediatric Dentistry (EAPD) proposes this best clinical practice guidance to help practitioners decide when and how to prescribe dental radiographs in children and adolescents. METHODS: Four expert working groups conducted each a systematic review of the literature. The main subjects were radiation protection, intraoral dental radiography (bitewing and periapical radiographs), panoramic radiography (PR) and cone-beam computed tomography (CBCT). In addition, three workshops were held during the corresponding EAPD Interim Seminar in Chania (Crete, Greece) in 2019. On the basis of the identified evidence, all invited experts presented their findings and during the workshops aspects of clinical relevance were discussed. RESULTS: Several clinical-based recommendations and statements were agreed upon. CONCLUSION: There is no or low-grade evidence about the efficacy of dental radiographic examinations in young populations. The given recommendations and rationales should be understood as best clinical practice guidance. It is essential to respect the radiological principles of an individualized and patient-specific justification. When a dental radiograph is required, its application needs to be optimized, aiming at limiting the patient's exposure to ionising radiation according to the ALADAIP principle (As Low As Diagnostically Achievable being Indication-oriented and Patient-specific).

Antibacterial properties and regenerative potential of Sr2+ and Ce3+ doped fluorapatites; a potential solution for peri-implantitis.

Scaffolds and implants in orthopaedics and regenerative dentistry usually fail because of bacterial infections. A promising solution would be the development of biomaterials with both significant regenerative potential and enhanced antibacterial activity. Working towards this direction, fluorapatite was synthesised and doped with Sr2+ and Ce3+ ions in order to tailor its properties. After experiments with four common bacteria (i.e. E. Coli, S. Aureus, B. Subtilis, B. Cereus), it was found that the undoped and the Ce3+ doped fluorapatites present better antibacterial response than the Sr2+ doped material. The synthesised minerals were incorporated into chitosan scaffolds and tested with Dental Pulp Stem Cells (DPSCs) to check their regenerative potential. As was expected, the scaffolds containing Sr2+-doped fluorapatite, presented high osteoconductivity leading to the differentiation of the DPSCs into osteoblasts. Similar results were obtained for the Ce3+-doped material, since both the concentration of osteocalcin and the RUNX2 gene expression were considerably higher than that for the un-doped mineral. Overall, it was shown that doping with Ce3+ retains the good antibacterial profile of fluorapatite and enhances its regenerative potential, which makes it a promising option for dealing with conditions where healing of hard tissues is compromised by bacterial contamination.

Management of discolouration following revitalization endodontic procedures: A case series.

AIM: To discuss the causes and management of tooth crown discolouration following regenerative/revitalization endodontic therapy (RET) and to present the decision-making process affecting three RET-related cases of crown discolouration. SUMMARY: This case series outlines several approaches used in the management of post-RET discolouration. The cases highlight the influence of the material used in creating a coronal seal on the choice and success of the management techniques provided. The first two cases highlight successful management of post-RET discolouration through the use of internal-external bleaching. The use of internal bleaching in the third case was not recommended; therefore, external bleaching followed by a direct composite veneer was carried out.

Exogenous mineralization of hard tissues using photo-absorptive minerals and femto-second lasers; the case of dental enamel.

A radical new methodology for the exogenous mineralization of hard tissues is demonstrated in the context of laser-biomaterials interaction. The proposed approach is based on the use of femtosecond pulsed lasers (fs) and Fe3+-doped calcium phosphate minerals (specifically in this work fluorapatite powder containing Fe2O3 nanoparticles (NP)). A layer of the synthetic powder is applied to the surface of eroded bovine enamel and is irradiated with a fs laser (1040 nm wavelength, 1 GHz repetition rate, 150 fs pulse duration and 0.4 W average power). The Fe2O3 NPs absorb the light and may act as thermal antennae, dissipating energy to the vicinal mineral phase. Such a photothermal process triggers the sintering and densification of the surrounding calcium phosphate crystals thereby forming a new, dense layer of typically ∼20 µm in thickness, which is bonded to the underlying surface of the natural enamel. The dispersed iron oxide NPs, ensure the localization of temperature excursion, minimizing collateral thermal damage to the surrounding natural tissue during laser irradiation. Simulated brushing trials (pH cycle and mechanical force) on the synthetic layer show that the sintered material is more acid resistant than the natural mineral of enamel. Furthermore, nano-indentation confirms that the hardness and Young's modulus of the new layers are significantly more closely matched to enamel than current restorative materials used in clinical dentistry. Although the results presented herein are exemplified in the context of bovine enamel restoration, the methodology may be more widely applicable to human enamel and other hard-tissue regenerative engineering. STATEMENT OF SIGNIFICANCE: In this work we provide a new methodology for the mineralisation of dental hard tissues using femtosecond lasers and iron doped biomaterials. In particular, we demonstrate selective laser sintering of an iron doped fluorapatite on the surface of eroded enamel under low average power and mid-IR wavelength and the formation of a new layer to substitute the removed material. The new layer is evaluated through simulated brushing trials and nano-indentation. From the results we can conclude that is more acid resistant than natural enamel while, its mechanical properties are superior to that of current restorative materials. To the best of our knowledge this is the first time that someone demonstrated, laser sintering and bonding of calcium phosphate biomaterials on hard tissues. Although we here we discuss the case of dental enamel, similar approach can be adopted for other hard tissues, leading to new strategies for the fixation of bone/tooth defects.

The effect on dental enamel of the frequency of consumption of fluoridated milk with a cariogenic challenge in situ.

OBJECTIVES: To evaluate the effect on enamel of varying the frequency of consumption of 1.0 mg F in milk once per day, twice per day or once every other day under cariogenic challenge in situ. MATERIALS AND METHODS: In a controlled, randomised, cross-over, single-blind study, 25 subjects wore an intra-oral lower removable appliance with enamel slabs for 21 days during each study arm. Subjects used F-free toothpaste, the cariogenic challenge comprising of five 2 min dippings per day in a 12% sucrose solution. Subjects dipped the appliances in 50 ml of 5.0 ppm fluoridated milk for five minutes during the test period once per day, twice per day, and once every other day and drank 200 ml of the same milk, once per day, twice per day (100 ml each time), or once every other day (200 ml) immediately on re-inserting their appliance in order to replicate topical and systemic effects. Slabs were analysed with surface microhardness (SMH) for protection against further demineralisation and transverse microradiography (TMR) to assess changes in mineralisation. RESULTS: Using SMH, 200 ml of 5.0 ppm F milk once per day was significantly better than 100 ml of 5.0 ppm F twice/day (p < 0.05) and 200 ml once every other day, but not significantly. Using TMR there was a statistically significant difference in mineral loss of enamel between baseline and treatment for all groups, but not between groups. CONCLUSIONS: Drinking 200 ml of 5.0 ppm milk once per day every day protected enamel against further demineralisation whereas all three frequencies were effective in promoting remineralisation.

A biocompatible decellularized pulp scaffold for regenerative endodontics.

AIM: To investigate the feasibility of decellularizing the entire dental pulp using a mild treatment protocol to develop a decellularized biological extracellular matrix scaffold for use in regenerative endodontic procedures. METHODOLOGY: Decellularized human dental pulps were assessed using histological and immunohistochemical methods, scanning electron microscope and DNA quantification assay. Cytotoxicity assays to determine decellularized scaffold biocompatibility were also performed. Decellularized scaffolds were seeded with human dental pulp stem cells and cell viability assessed using Live/Dead® stain. Quantitative data were analysed statistically using Student's t-test and one-way analysis of variance to compare mean values between groups depending on group numbers. RESULTS: Assessment of decellularized tissues revealed an acellular matrix with preservation of native tissue histoarchitecture and composition. Decellularized tissues showed no evidence of cytotoxicity, with cell growth in direct contact with the scaffold and no reduction in cellular activity following extract incubation. Furthermore, the scaffold was able to support human dental pulp stem cell viability and attachment following recellularization. CONCLUSIONS: Promising results were observed in developing a decellularized biological scaffold derived from the dental pulp with the perseveration of extracellular structural components which are required for tissue-specific regeneration.

A prospective clinical study of regenerative endodontic treatment of traumatized immature teeth with necrotic pulps using bi-antibiotic paste.

AIM: To evaluate the treatment outcomes of a revitalization endodontic technique (RET) for the management of traumatized immature teeth with necrotic pulps in children. METHODOLOGY: Fifteen healthy children (age range = 7-10 years) with traumatized immature maxillary incisors with necrotic pulps treated with bi-antibiotic revitalization endodontic technique were prospectively assessed over approximately two years (mean = 22 months). One operator undertook all treatments, clinical reviews and standardized radiographic exposures with radiographic analysis being carried out by two calibrated experienced clinicians. Crown colour change was assessed using an objective published methodology. Wilcoxon signed-rank test was used to compare root lengths, root dentinal widths and apical foramen widths over time. RESULTS: Interoperator measurement reliability was consistently strong for all measurements. There was no significant difference in root lengths or root dentinal wall widths following RET. A significant difference in apical foramen widths was observed after 2 years (P = 0.013) with resolution of clinical signs of infection in all cases. Despite omitting minocycline and using Portland cement (nonbismuth containing cement), a noticeable crown colour change (yellower, redder and lighter), as measured by an objective colour measurement system with ΔE = 7.39, was recorded. Most patients, however, were satisfied with the aesthetic outcome. CONCLUSION: Traumatized immature teeth with necrotic pulps treated with revitalization endodontic technique did not demonstrate continuation of root development or dentine formation when assessed by periapical radiographs. However, apical closure and periodontal healing were observed. A measurable change in crown colour (yellower, redder and lighter), with mostly no aesthetic concern to the patients/parents, was also observed.

Comparison of the newer preventive therapies on remineralisation of enamel in vitro.

OBJECTIVES: To investigate in vitro the effect of MI Paste, MI Paste Plus and 2800ppm fluoride (F) toothpaste (TP) on the remineralisation of enamel subsurface lesions and to compare these to the effect of 1450ppm and 0ppm F toothpastes. METHODS: Enamel subsurface lesions were created in bovine enamel slabs (n=120) which were assigned randomly to five groups; (1) 0ppm F TP, (2) 1450ppm F TP, (3) 2800ppm F TP, (4) 1450ppm F TP+MI Paste (Tooth Mousse-TM,10% w/v CPP-ACP) and (5) 1450ppm F TP+MI Paste Plus (Tooth Mousse Plus,10% w/v CPP-ACP, 900ppm F as 0.2% w/w sodium fluoride). The enamel slabs were subjected to a pH cycling regimen for 21days. Quantitative Light-induced Fluorescence (QLF) images were taken and analysed. Data analysis was carried out using one way ANOVA. RESULTS: In all groups, both ΔF (percentage fluorescence loss) and ΔQ (ΔF times the area) values improved significantly within the same group after the treatment. In addition, the mean difference in ΔF of the non-fluoride control group was significantly lower than all other groups but not for the 2800ppm F- group. Whereas the mean difference in ΔQ of the non-fluoride control of group was significantly lower when compared with all other groups (p<0.05). CONCLUSIONS: Both MI Paste and MI Paste Plus when used in conjunction with 1450ppm F did not show a significant increase in efficacy for the remineralisation of bovine enamel subsurface lesions in the model used in this study. CLINICAL SIGNIFICANCE: Newer preventive agents such as MI paste and MI paste plus are advocated as promoting remineralisation when used in addition to routine oral care. This in vitro study shows that they may have a limited value in promoting remineralisation over and above that of 1450ppm F toothpaste used twice a day.

ß-pyrophosphate: A potential biomaterial for dental applications.

Tooth hypersensitivity is a growing problem affecting both the young and ageing population worldwide. Since an effective and permanent solution is not yet available, we propose a new methodology for the restoration of dental enamel using femtosecond lasers and novel calcium phosphate biomaterials. During this procedure the irradiated mineral transforms into a densified layer of acid resistant iron doped ß-pyrophosphate, bonded with the surface of eroded enamel. Our aim therefore is to evaluate this densified mineral as a potential replacement material for dental hard tissue. To this end, we have tested the hardness of ß-pyrophosphate pellets (sintered at 1000°C) and its mineral precursor (brushite), the wear rate during simulated tooth-brushing trials and the cytocompatibility of these minerals in powder form. It was found that the hardness of the ß-pyrophosphate pellets is comparable with that of dental enamel and significantly higher than dentine while, the brushing trials prove that the wear rate of ß-pyrophosphate is much slower than that of natural enamel. Finally, cytotoxicity and genotoxicity tests suggest that iron doped ß-pyrophosphate is cytocompatible and therefore could be used in dental applications. Taken together and with the previously reported results on laser irradiation of these materials we conclude that iron doped ß-pyrophosphate may be a promising material for restoring acid eroded and worn enamel.

Regenerative endodontics: a true paradigm shift or a bandwagon about to be derailed?

AIMS: Regenerative endodontic techniques (RETs) have been hailed as a paradigm shift for the management of traumatised non-vital immature permanent anterior teeth. In this article the aim was to critically appraise the literature with regards to the outcome of regenerative endodontics on root development. METHODS: Critical review of the literature where regenerative endodontic techniques have been used in the management of immature non-vital teeth with continuation of root development as the main outcome reported. RESULTS: Most studies published were in the form of case reports and series with very few randomised controlled trials with a high risk of bias. Continuation of root development following the use of RET has been shown to be unpredictable at best with lower success in those teeth losing vitality as a result of dental trauma. CONCLUSIONS: Despite the high success of regenerative endodontics in terms of periodontal healing including resolution of clinical and radiographic signs and symptoms of infection, continuation of root development remains an unpredictable outcome. The use of a blood clot as a scaffold in regenerative endodontics should be reviewed carefully as that might offer an environment for repair rather than regeneration. In addition, preservation of structures, such as Hertwig's epithelial root sheath, may have an important bearing on the success of this approach and should be further investigated.

The effect of premature extraction of primary teeth on the subsequent need for orthodontic treatment.

AIM: This was primarily to examine the effect of premature extraction of primary teeth (PEPT) on subsequent malocclusion and need for orthodontic treatment in the permanent dentition. The secondary aim was to correlate the effect of PEPT with loss of space in the primary and mixed dentitions. METHODS: A predefined protocol was developed and registered prospectively with PROSPERO database. The electronic databases, searched, were MEDLINE, EMBASE, PubMed, and Cochrane Central Register of Controlled Trials. The study designs considered for inclusion were controlled trials, cohort, and case-control studies. Risk of bias was assessed using a validated quality assessment tool. RESULTS: 513 studies were identified. Sixteen studies were included in the systematic review, one study reported on malocclusion, and 15 studies reported on space changes. Narrative synthesis was undertaken owing to the heterogeneity of the included studies. No study examined the effect of PEPT on orthodontic need. Most studies reported on space dimensions used a split-mouth design and were at a high risk of bias. CONCLUSIONS: The included literature identified that PEPT led to various features of malocclusion and space loss in the mixed and permanent dentitions. No studies, that met the inclusion criteria, described the effect of PEPT on the subsequent need for orthodontic treatment.

Comparison of residual salivary fluoride retention using amine fluoride toothpastes in caries-free and caries-prone children.

AIM: This was to compare the salivary fluoride levels following tooth brushing with amine fluoride toothpastes containing three different concentrations of F (250 ppm F, 500 ppm F and 1250 ppm F) and to evaluate the effect of rinsing with water on the oral fluoride levels up to 90 min. METHODS: A double blind randomised six-arm crossover study was conducted with 32 child participants. Patients were divided into two groups depending on their caries experience with caries-free group (n = 17, mean age = 72.9 months) and caries-prone group (n = 15, mean age = 69.6 months, mean dmfs = 12.3). Each participant brushed their teeth with a smear of dentifrice containing (250 ppm, 500 ppm and 1250 ppm F toothpastes) for 60 s. After spitting out the dentifrice/saliva slurry, participants either rinsed with water or did not rinse at all. Samples of whole mixed unstimulated saliva were collected at 0 (baseline), 1, 15, 30, 45, 60 and 90 mins post-brushing/rinsing. RESULTS: After completing the study on residual fluoride concentration it was found that caries was not a significant variable (p = 0.567) while every other variable was (all p values <0.001). Time, toothpaste F concentration and rinse had significant effects (p < 0.001). In general, higher residual salivary F concentrations were found with increased F concentration in toothpastes and when no rinsing was performed after brushing. CONCLUSION: The results of this study support the current recommendation of using toothpastes with >1000 ppm F concentration in children with an increased caries risk in addition to spitting excess toothpaste with no rinsing following brushing.

Molar incisor hypomineralisation: experience and perceived challenges among dentists specialising in paediatric dentistry and a group of general dental practitioners in the UK.

AIM: To assess the views and experience of the UK dentists specialising in paediatric dentistry (trainees) about molar incisor hypomineralisation (MIH) and compare the findings with the responses from a group of UK general dental practitioners. METHOD: A web-based questionnaire was sent to dentists undergoing specialist training in paediatric dentistry. The same questionnaire was completed by a group of general dentists who stated an interest in treating children, with various levels of experience. The questionnaire sought information on clinical experience and the views of the dentists on the impact of MIH on children and families. RESULTS: Specialty trainees (37) from different paediatric dental departments in the UK completed the online survey, giving a total response rate of 71%. The questionnaire was also completed by 31 general dental practitioners. There was difficulty in distinguishing MIH from other conditions for both groups. Increased sensitivity of affected teeth was the most frequently encountered problem with 51% of the trainees and 76% of the dentists saying this was often or always a challenge. The trainees were particularly concerned about the pain children experienced and about the appearance of the condition. Both groups felt that parental anxiety occurred in almost all cases. CONCLUSIONS: Both groups felt that MIH presents several clinical challenges and has a negative effect on the quality of life of the affected children and their families. There were significant differences in the views and perceptions between the two groups.

A comparison of the presentation of molar incisor hypomineralisation in two communities with different fluoride exposure.

AIM: To compare the clinical presentation of two cohorts of children diagnosed with molar incisor hypomineralisation (MIH) and living in areas of low and high background fluoridation. METHODS: The study population comprised 12-year-old children participating in the 2008-2009 National Dental Epidemiological Programme in five regions in Northern England. Participating dentists were trained and calibrated in the use of the modified Developmental Defects of Enamel Index. Children were examined at school under direct vision with the aid of a dental mirror. First permanent molars and incisors were recorded for the presence and type of enamel defects greater than 2 mm. A diagnosis of MIH was ascribed to any child with a demarcated defect in any first permanent molar. Risk ratios for the occurrence of demarcated, diffuse and hypoplastic defects were generated for MIH children in the fluoridated and non-fluoridated area. RESULTS: 3,233 children were examined. The prevalence of MIH in the fluoridated community was 11 % and in the non-fluoridated community was 17.5 %. Incisors in children with MIH were at greater risk of having demarcated defects (risk ratio 4.0, 3.6-4.5) and diffuse defects (risk ratio 2.2, 2.0-2.5). Molars in children with MIH were at greater risk of diffuse defects (risk ratio 4.4, 3.8-5.0). The teeth of children with MIH living in the fluoridated area were at greater risk of demarcated defects for both incisors (risk ratio 1.6, 1.3-2.0) and molars (risk ratio 1.3, 1.2-1.5) relative to the teeth of MIH children living in the non-fluoridated area. CONCLUSIONS: Children with MIH were at increased risk of both diffuse and demarcated defects in their incisors. Children with MIH living in the fluoridated area were at increased risk of diffuse and demarcated defects relative to MIH children living in the non-fluoridated area.