The effect of resin infiltration and oxidative pre-treatment on microshear bond strength of resin composite to hypomineralised enamel

Pretreatments to bonding on enamel and dentin disorders: a systematic review

INTRODUCTION

This systematic review focuses on structural anomalies of enamel and dentin such as fluorosis (F), molar-incisor hypomineralization (MIH), amelogenesis imperfecta (AI), dentinogenesis imperfecta (DI), osteogenesis imperfecta (OI), and X-linked hypophosphatemia (XLH). These pathologies affect up to 31% of the population, posing challenges in the adhesion of direct restorations. The primary objective of this analysis is to examine the survival rate and/or bonding resistance of direct restorations on tissues affected by enamel and dentin disorders in humans. We aim to provide precise clinical recommendations for dentists to choose the appropriate bonding pretreatment for various enamel and dentin disorders.

METHODS

We systematically searched the medical literature to identify abstracts of interest indexed between 1993 and May 2024, from 4 databases (PubMed, PMC-PubMed, Web of Science and Cochrane Library). The results are reported following the PRISMA statement. The GRADE approach was used to assess the risk of bias.

RESULTS

The two authors included 27 studies out of the 600 identified. The data extracted from these studies are highly heterogeneous, and the mentioned bonding protocols are all different. 15 articles pertain to F, 7 to MIH, 5 to AI, and none focus on HSPM, dentin disorders and XLH. We identified 12 pretreatments of enamel or dentin (7 for F, 2 for MIH, and 3 for AI), including 3 strong recommendations. Additional studies are necessary to confirm the effectiveness of certain pretreatments. In developmental enamel defects, the main recommendation we collected is to bond on enamel with an etch-and-rinse technique on F and MIH. Considerations with lower strength of evidence include a deproteinization step on enamel on F, MIH and AI and modifications of the etching parameters on F and AI. The research strategy was registered on the Prospero platform (CRD42023447502).

Influence of different pre-treatments on the resin infiltration depth into enamel of teeth affected by molar-incisor hypomineralization (MIH)

OBJECTIVES

This in vitro pilot study aimed to evaluate whether different pre-treatments (demineralization, deproteinization, (chemo-)mechanical reduction of the surface layer) influence the penetration depth of a resin infiltrant into MIH-affected enamel compared to initial carious lesions.

METHODS

Thirty extracted human permanent molars with non-cavitated initial carious lesions (n = 5) or MIH (n = 25) were chosen and randomly assigned to six experimental groups: IC: initial caries; M: MIH; MN: MIH, 5.25% sodium hypochlorite; MM: MIH, microabrasion; MA: MIH, air abrasion; MAN: MIH, air abrasion and 5.25% sodium hypochlorite. A modified indirect dual fluorescence staining method was adopted to assess the penetration depth (PD) of the resin infiltrant and the lesion depth (LD) by confocal laser scanning microscopy (CLSM). Exemplarily, scanning electron microscopic (SEM) images were captured. The relationship between group assignment and penetration/lesion depth was estimated using a linear mixed model incorporating the tooth as random effect (two observations/tooth). The significance level was set at p < 0.05.

RESULTS

For MIH-affected molars, the mean PD (in µm; median, [minimum-maximum]) were M (178.2 [32.5-748.9]), MN (275.6 [105.3-1131.0]), MM (48.7 [0.0-334.4]), MA (287.7 [239.4-491.7]), and MAN (245.4 [76.1-313.5]). Despite the observed differences in PD between the groups, these could not be statistically verified (Bonferroni, p = 0.322). The percentage penetration was significantly higher for IC than for MIH groups (Bonferroni, p < 0.05).

SIGNIFICANCE

Compared to IC, resin infiltration into MIH-affected enamel ist more variable. Different pre-treatments influence the resin penetration into developmentally hypomineralized enamel to a fluctuating level.

Short-term Results of the Masking Effect of an Infiltrant Resin on Mild Molar Incisor Hypomineralization Lesions in Anterior Teeth

This non-controlled clinical study evaluated the masking effect of an infiltrant resin on mild molar incisor hypomineralization (MIH) lesions. Thirty MIH-affected anterior teeth with creamy/ white opacities from 12 children aged 6-15 years received the application of an infiltrant resin (Icon- DMG). Standard photographs were taken before (T1), immediately after (T2), and 1 week after (T3) resin infiltration. Two calibrated examiners qualitatively analyzed the color match using the Fédération Dentaire Internationale (FDI) scale. The binomial distribution test analyzed the scores of the color match at T1 with T2 and T3, and McNemar's test analyzed the scores of the color match between T2 and T3 (α=0.05). There was a significant increase in color match between T1 and T2 (p=0.0005), between T1 and T3 (p=0.0005), and between T2 and T3 (p=0.0019). It was concluded that infiltrant resin was effective in improving the esthetic appearance of creamy/white opacities on MIH-affected anterior teeth.

Proteomic Analyses Discern the Developmental Inclusion of Albumin in Pig Enamel: A New Model for Human Enamel Hypomineralization

Excess albumin in enamel is a characteristic of the prevalent developmental dental defect known as chalky teeth or molar hypomineralization (MH). This study uses proteomic analyses of pig teeth to discern between developmental origin and post-eruptive contamination and to assess the similarity to hypomineralized human enamel. Here, the objective is to address the urgent need for an animal model to uncover the etiology of MH and to improve treatment. Porcine enamel is chalky and soft at eruption; yet, it hardens quickly to form a hard surface and then resembles human teeth with demarcated enamel opacities. Proteomic analyses of enamel from erupted teeth, serum, and saliva from pigs aged 4 (n = 3) and 8 weeks (n = 2) and human (n = 4) molars with demarcated enamel opacities show alpha-fetoprotein (AFP). AFP expression is limited to pre- and perinatal development and its presence in enamel indicates pre- or perinatal inclusion. In contrast, albumin is expressed after birth, indicating postnatal inclusion into enamel. Peptides were extracted from enamel and analyzed by nano-liquid chromatography-tandem mass spectrometry (nanoLC-MS/MS) after tryptic digestion. The mean total protein number was 337 in the enamel of all teeth with 13 different unique tryptic peptides of porcine AFP in all enamel samples but none in saliva samples. Similarities in the composition, micro-hardness, and microstructure underscore the usefulness of the porcine model to uncover the MH etiology, cellular mechanisms of albumin inclusion, and treatment for demarcated opacities.

Dental and Dental Hygiene Students' Knowledge and Capacity to Discriminate the Developmental Defects of Enamel: A Self-Submitted Questionnaire Survey

Background: A prompt and accurate diagnosis of developmental defects of enamel (DDE) is mandatory for proper treatment management. This cross-sectional survey, designed and carried out using anonymous self-administered questionnaires, aimed to assess dental and dental hygiene students’ knowledge and their capability to identify different enamel development defects. Methods: The questionnaire consisted of twenty-eight closed-ended questions. Two different samples of undergraduate students were selected and enrolled: a group of dental hygiene (GDH) students and a group of dental (GD) students. A multivariate logistic regression was performed by adopting the correct answers as explanatory variables to assess the difference between the two groups. Results: Overall, 301 completed questionnaires were analyzed: 157 from the GDH and 144 from the GD. The dental student group showed better knowledge than the GDH of enamel hypomineralization and hypoplasia (p = 0.03 for both). A quarter (25.25%) of the total sample correctly identified the period of development of dental fluorosis with a statistically significant difference between the groups (p < 0.01). Amelogenesis imperfecta (AI) was identified as a genetic disease by 64.45% of the sample, with a better performance from the GD (p = 0.01), while no statistical differences were found between the groups regarding molar incisor hypomineralization. Multivariate analysis showed that AI (OR = 0.40, [0.23;0.69], p < 0.01) and caries lesion (OR = 0.58, [0.34;0.94], p = 0.03) were better recognized by the GD. Conclusions: Disparities exist in the knowledge and management of DDE among dental and dental hygiene students in Italy; however, significant knowledge gaps were found in both groups. Education on the diagnosis and treatment of DDE during the training for dental and dental hygiene students needs to be strongly implemented.

Effectiveness of sodium hypochlorite treatment on the bonding of four adhesive systems to fluorotic enamel

The study evaluated the effect of sodium hypochlorite (NaOCl) treatment on fluorotic enamel bonding of four adhesive systems. They were Single Bond 2 (SB2), Prime&Bond NT (PBN), Clearfil SE Bond (CSB), and Single Bond Universal (SBU). One hundred eighteen extracted moderate fluorotic molars were divided into eight groups according to NaOCl pretreatment and four adhesive systems. The microshear bond strength (μSBS), etching pattern, and penetration depth (PD) were observed. The statistical method was two-way ANOVA and least significant difference (LSD) test (α=0.05). The application of NaOCl significantly increased the μSBS of PBN and SBU (p<0.05). The enamel-etching pattern of CSB and SBU was deeper under SEM. A noticeable increase of PD was in SB2 and SBU after the application of NaOCl (p<0.05). Pretreatment of 5.25% NaOCl for the 60 s can increase μSBS of PBN and SBU, PD of SB2 and SBU, and improve enamel-etching pattern of CSB and SBU to fluorotic enamel.

Management of Teeth Affected by Molar Incisor Hypomineralization Using a Resin Infiltration Technique—A Systematic Review

In recent years, an increase in children diagnosed with molar incisor hypomineralization (MIH) has been observed. Children with MIH show a high failure rate with conservative treatment. The ICON® system (DMG, Hamburg, Germany), which is an infiltration of decalcified lesions with resin, may strengthen the tooth structure, improve its aesthetics, and cure hypersensitivity. The following article is a systematic review based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol. Scientific articles in the PubMed and Google Scholar databases describing the use of the ICON system in the treatment of MIH published in the years 2012–2022 were analyzed. Two independent study authors selected publications that show that the ICON system can be used during the treatment of children with MIH. So far, in the literature, there are no standardized protocols for the dental treatment of patients with hypomineralization of the incisors using the ICON system. Therefore, clinicians rarely use this method of treatment. The ICON system may be successfully used to infiltrate tooth decalcification in children with MIH. However, the depth of infiltration and the achievement of enamel hardness after such therapy are not precisely defined.

Evaluation of developmentally hypomineralised enamel after surface pretreatment with Papacarie Duo gel and different etching modes: an in vitro SEM and AFM study

PURPOSE

This study aimed at investigating the surface morphology and nanotopography of normal enamel (NE) and developmentally hypomineralised enamel (HE) when subjected to various pretreatment protocols under scanning electron microscopy (SEM) and atomic force microscopy (AFM).

METHODS

Sixteen NE, 16 creamy/white (CW) HE and 16 yellow/brown (YB) HE specimens sectioned from extracted hypomineralised first permanent molars (FPMs) were included in this study. They were randomly distributed into 12 experimental groups (n = 4). Each group involved the following: (1) deproteinisation with Papacarie Duo^® gel or no deproteinisation, and (2) the use of Scotchbond™ Universal Adhesive (Scotchbond) in self-etch (SE) mode or 37% phosphoric acid etchant. Subsequently, the surface morphology and nanotopography of pretreated enamel specimens were evaluated under SEM and AFM, respectively.

RESULTS

SEM observation showed that deproteinisation with Papacarie Duo^® gel before phosphoric acid etching led to favourable etching patterns. This was consistent across all groups irrespective of the type of enamel specimen and the severity of hypomineralisation. In contrast, AFM results identified three factors that influenced surface parameters: (1) type of enamel specimen, (2) severity of hypomineralisation and (3) etching mode. YB HE recorded higher surface roughness values than CW HE and NE when subjected to the same pretreatment protocol. Deproteinisation and the application of Scotchbond in SE mode led to minimal topographic changes; however, acid etching was associated with an increase in surface roughness.

CONCLUSION

Deproteinisation with Papacarie Duo^® gel followed by acid etching contributed to improved etching patterns on HE.

Shear bond strength of resin modified glass ionomer cement following photodynamic therapy, Er,Cr:YSGG and chlorhexidine in hypoplastic primary teeth

PURPOSE

This study investigates the micro shear bond strength of resin-modified glass ionomer cement (RMGIC) bonded to hypoplastic teeth after the application of chlorhexidine (CHX), sodium hypochlorite (NaOCl), Er;Cr:YSGG and methylene blue mediated antimicrobial photodynamic therapy (APDT).

METHODS

A total sample of 60 erupted and extracted hypoplastic teeth collected from < 16 years children were subjected to different conditioning protocols including control group that involved bonding of hypoplastic teeth with RMGIC; CHX and NaOCl groups that included hypoplastic enamel being treated with 0.2% CHX and 2% NaOCl solution for 30 s followed by rinsing and drying for 5 s, MB-PDT group involved methylene blue photosensitizer and Er,Cr:YSGG group. All specimens were processed for microshear bond strength in a universal tester. The fractured surface was examined using a stereomicroscope at 40 × magnification and categorized under adhesive, cohesive and mixed.

RESULTS

The highest microshear bond strength was noted for the control group (∼29 MPa). Whereas the specimens conditioned by NaOCl showed the lowest microshear bond strength (∼17 MPa). Among the treatment groups, APDT showed the highest bond strength values (∼22 MPa) as compared to chemical disinfection protocols. However, Er, Cr:YSGG showed slightly lower microshear bond strength as compared to APDT. No significant difference was noted between CHX and NaOCl groups (p > 0.05). There was a statistically significant difference when all the groups were compared together (p < 0.05). Microscopic analysis revealed that specimens bonded after APDT showed the highest adhesive failures (70%). The highest cohesive failures were seen in NaOCl group (40%). The mixed type of failures was seen in the control groups with none appearing for chemical disinfection protocols.

CONCLUSIONS

This study concludes that APDT could be a potential therapeutic strategy for increasing the microshear bond strength of RMGIC to hypoplastic enamel.

The influence of lesion characteristics on application time of an infiltrate applied to MIH lesions on anterior teeth: An exploratory in vivo pilot study

OBJECTIVES

To evaluate the factors that influences the kinetics of resin infiltration of molar incisor hypomineralisation (MIH) lesions on permanent anterior teeth.

METHODS

Demarcated MIH lesions with homogeneous and heterogeneous lesion body appearance, Types 1 (n = 14) and 2 (n = 18), respectively, were selected. After removal of the lesion surface layer using a tapered diamond finishing bur, the lesions were etched and ethanol was applied to the lesions and it was determined if the lesion was still visible or not. Images were taken just prior infiltrant (Icon; DMG) application (T₀), during the infiltration process (T_x) and when infiltration had ceased progressing or opacity disappearance was clinically apparent (T_max). Surface-area measurements of the opacity and infiltrated area were calculated and the infiltration proportion (IP_x) was calculated over the infiltration time.

RESULTS

Type 1 and positive ethanol test lesions showed significantly lower mean T_max (3.4 min) in comparison with Type 2 and negative ethanol test lesions (9.9 min) [Student t-test/Fisher's exact test; p < .01]. A non-linear correlation was observed (R² = 0.88) indicating that the IP_x was rapid at the beginning of resin application, decreasing over time.

CONCLUSION

In comparison with Type 1 and positive ethanol test lesions, Type 2 and negative ethanol test lesions require longer application time to infiltrate.

CLINICAL SIGNIFICANCE

MIH-lesion type and the 'ethanol test' were reliable predictive factors for the application time required for infiltrating MIH lesions on permanent anterior teeth.

Molar Incisor Hypomineralisation: Current Knowledge and Practice

BACKGROUND

Molar incisor hypomineralisation (MIH) is a common developmental dental condition that presents in childhood. Areas of poorly formed enamel affect one or more first permanent molars and can cause opacities on the anterior teeth. MIH presents a variety of challenges for the dental team as well as functional and social impacts for affected children.

OBJECTIVES

Here, we provide an up-to-date review of the epidemiology, aetiology, diagnosis and clinical management of MIH.

MATERIALS AND METHODS

A review of the contemporary basic science and clinical literature, relating to MIH, was undertaken using information obtained (up to 10 April 2020) from the electronic databases PubMed, Scopus, Web of Science and the Cochrane Library.

RESULTS

There is a growing body of evidence relating to the aetiology, presentation and clinical management of MIH. Current knowledge appears to be focused on potential genetic aspects, as well as the development and validation of indices for the diagnosis and management of MIH. There has also been increasing recognition of the global and individual burden of this common condition.

CONCLUSIONS

Dental health professionals should regularly appraise the basic science and clinical MIH literature to ensure that they provide the best possible short- and long-term care for their young patients.

Structural integrity of MIH-affected teeth after treatment with fluoride varnish or resin infiltration: An 18-Month randomized clinical trial

OBJECTIVE

To evaluate the influence of fluoride varnish (FV) therapies or resin infiltration (RI) to maintain the structural integrity of Molar Incisor Hypomineralization (MIH) -affected teeth.

METHODS

Fifty-one children aged 6-12 years with at least one incisor and one first permanent molar with yellow/brown MIH opacities were included. Patients were randomly allocated into three groups: FV - Fluoride Varnish (Duraphat); FV+etch - Fluoride Varnish (Duraphat) after enamel etching with 37% phosphoric acid; or RI - Resin Infiltration system (Icon). Opacities were monitored for 18 months. The primary outcome was the loss of integrity due to post-eruptive enamel breakdown (PEB). Covariables included sex, age, DMFT index, opacity colour, plaque index, number of MIH-affected teeth, and number of MIH-affected surfaces. Fisher's Exact was used to test the association of treatments with PEB, the Kaplan-Meyer method analysed the survival rates and Cox-regression determined which covariables would predict failure (α=0.05).

RESULTS

From a total of 235 teeth, the PEB rate for RI (6.1%) was significantly lower (p<0.05) than FV (17.9%; OR 3.0, 95%CI 1.07, 8.48) and FV+etch (17.3%; OR 3.1, 95%CI 1.13, 8.73). DMFT index >3, brown opacities, cusp involvement, and age between 6-8 years predicted PEB (p<0.05).

CONCLUSIONS

Resin infiltration positively influenced the structural integrity maintenance of MIH-affected teeth by decreasing the risk of enamel breakdown over18 months follow-up. Registry of Clinical Trials (RBR-8wwk3n).

CLINICAL RELEVANCE

Resin infiltration proved to be a more efficacious intervention to maintain the structural integrity of MIH-affected teeth than fluoride varnish therapies.

Long-Term Survival of Enamel-Defect-Affected Teeth

There has been considerable research focussed on the occurrence and aetiology of developmental defects of enamel, but less is known about the extent to which enamel-defect-affected teeth may be at greater risk for dental caries. The Dunedin Multidisciplinary Health and Development Study is a prospective cohort study of 1,037 children born in Dunedin, New Zealand, between April 1, 1972, and March 31, 1973. Participants were examined for the presence of developmental defects of enamel at the age of 9 years and then repeatedly for the occurrence of dental caries through to the age of 45 years. After controlling for confounding variables, incisor teeth affected by demarcated opacities at the age of 9 were 3.4 times more likely to be restored than teeth unaffected by defects. Incisors with diffuse opacities and hypoplasia or combinations of defects were 2.8 times more likely to be restored. Molars with enamel defects of any type did not have any significantly different risk for being subsequently restored or lost due to caries than unaffected molars, except those affected by diffuse opacities, which were at 0.4 times the risk of being lost due to caries. Dental clinicians should be aware that enamel-defect-affected teeth are not necessarily at greater risk for tooth loss due to caries in the long term, but permanent incisors affected by enamel defects are at higher risk of receiving restorative intervention.

Molar Incisor Hypomineralisation-To Extract or to Restore beyond the Optimal Age?

The management of compromised first permanent molars (FPMs) in children presents a clinical challenge to the dental team. Hypomineralised FPMs in molar incisor hypomineralisation (MIH) conditions could undergo post-eruptive breakdown, making them susceptible to caries, leading to their subsequent loss. The planned extraction of compromised FPMs is a valid alternative to complex restorative treatment. However, establishing the presence or absence of third permanent molars, amongst other considerations, is crucial to reaching a successful outcome. Clinicians should understand the importance of an orthodontic examination around the age of 8 years old with regard to establishing a differential therapeutic decision about the ideal timing of MIH-affected FPMs’ extraction in children. The aim of this article is to highlight that, with an interdisciplinary approach, a good outcome can be achieved following the extraction of poorly prognosed FPMs. The most cost-effective way of addressing MIH-affected FPMs is extraction, followed by orthodontic space closure when indicated. This obviates the need for the repeated restorative replacement and saves perfectly healthy premolars from being extracted for space creation in orthodontic treatment in several clinical scenarios.

Strategies to optimize bonding of adhesive materials to molar-incisor hypomineralization-affected enamel: A systematic review

BACKGROUND

Children with first permanent molar affected by molar-incisor hypomineralization (MIH) show high treatment failure rate.

AIM

To conduct a systematic review on bonding of adhesive materials to MIH-affected enamel, so as to identify all the methods suggested to optimize it and to determine the best bonding protocol(s).

DESIGN

An exhaustive literature search was conducted on MEDLINE/PubMed, the Cochrane Library, and Web of Science databases, up to October 2018. Laboratory and clinical studies, involving adhesive restorations bonded to MIH-affected enamel, with at least a comparative group were included. Two authors independently selected studies, collected data, and assessed bias risk.

RESULTS

After title and abstract review and duplicate exclusion, 14 articles were selected on the 496 eligible papers. After full reading, 4 articles were excluded. Finally, 10 studies (6 laboratory and 4 clinical studies) were included.

CONCLUSIONS

Bond strength of composite was not significantly different when using self-etch compared with etch-and-rinse adhesives. Deproteinization after etching for etch-and-rinse adhesives enhanced bond strength; this could allow to keep MIH-affected enamel. Icon^® showed an erratic penetration; however, a preliminary deproteinization after etching could improve bond strength. A study reported no significant differences in sealant retention rate, whereas another recommended to previously apply an adhesive.

Anti-caries effect of resin infiltrant modified by quaternary ammonium monomers

OBJECTIVES

Resin infiltrant is used in early enamel caries. However, commercial resin infiltrant lacks persistent antibacterial activity. Dimethylaminododecyl methacrylate (DMADDM) was added to resin infiltrant to give it sustainable antibacterial properties and inhibit demineralization.

METHODS

After the application of resin infiltrant to bovine enamel, cytotoxicity, surface roughness, and aesthetics were assessed. A multi-species biofilm was incubated on the enamel disk before and one month after microbial-aging. After a 48-h anaerobic incubation, biomass accumulation, metabolic activity, and lactic acid were analyzed using a crystal violet assay, an MTT (3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, and a lactic acid assay. Biofilm structure and composition were determined by live/dead staining, exopolysaccharide (EPS) staining, scanning electron microscopy (SEM), and quantitative polymerase chain reaction (qPCR). The depth and content of demineralization were tested by transverse microradiography (TMR).

RESULTS

Incorporating DMADDM did not increase the cytotoxicity or change the physical properties when the mass fraction of the DMADDM was 2.5-10 %. The modification decreased the amount of bacterial biofilm, metabolic activity, lactic acid production, EPS, and the proportion of Streptococcus mutans in the biofilms. It also provided anti-demineralization effects. The surface roughness and antibacterial ability were not changed after one month of microbial-aging.

CONCLUSION

The incorporation of DMADDM improved the antibacterial and anti-demineralization effects of the material. It demonstrated a sustained antibacterial effect.

CLINICAL SIGNIFICANCE

The antibacterial modification might be a potential choice for future clinical applications to inhibit early enamel caries.

Knowledge and Management of First Permanent Molars with Enamel Hypomineralization among Dentists and Orthodontists

Purpose: Molar Incisor Hypomineralization (MIH) is a developmental enamel anomaly of systemic origin affecting the first permanent molars and often the permanent incisors. Despite MIH being a prevalent anomaly, its diagnosis and management are challenging for practitioners; including poor anesthesia, failure of restorations, rapid enamel breakdown, poor resin adhesion, and related child anxiety. This study aimed to evaluate knowledge regarding and management of MIH amongst orthodontists and dentists. Study design: The study was performed from March to September 2017 and included 336 dentists and 32 orthodontists. Questionnaires comprised questions on MIH diagnosis, socio-demographic characteristics of the subjects, and photographs of a case of MIH with related questions regarding management. Results: Our results showed that 48% of dentists and 25% of orthodontists misdiagnosed MIH; with misdiagnosis associated with graduation prior to 1986 (p < 0.001). Amongst dentists, 59% applied a fluoridated product and 34% applied fissure sealants in the case of moderate MIH. The application of fluoride was associated with graduation after 1986 (p < 0.0001).Conclusion: Large disparities about knowledge and management of MIH exist between dental practitioners in France. Education regarding diagnosis and management of MIH is necessary.

Underlying Resin Infiltration and Direct Composite Veneers for the Treatment of Severe White Color Alterations of the Enamel: Case Report and 13-Month Follow-Up

Pronounced white color alterations due to structural anomalies of the enamel are often insufficiently masked by bleaching techniques or resin infiltration procedures alone. This frequently leads to the choice of more invasive prosthetic restorations in order to correct tooth color and form. This article describes a minimally invasive treatment option for esthetic and functional rehabilitation in the case of a 13-year-old female patient with suspected severe fluorosis and misalignment of the anterior teeth. The restorations were performed using underlying resin infiltration to homogenize the tooth shade. In a second step, direct composite veneers were applied on top to attain a natural tooth color and adjust tooth alignment and form. By joining the two minimally and noninvasive techniques, this treatment option combines the directive for preservation of hard tooth structure while treating adolescents with the benefits of easy adaptation and repair when the occlusion is still in adjustment.

The efficacy of a bioglass (45S5) paste temporary filling used to remineralize enamel surfaces prior to bonding procedures

OBJECTIVES

The efficacy of using a 45S5 Bioglass paste as a remineralizing temporary filling material was compared to fluoride gel (1.23% acidulated-phosphate-fluoride, Gelato Gel, NJ, USA) applied for 24 h and for 4 min and to a temporary filling material (Caviton; GC, Tokyo, Japan).

METHODS

66 extracted human premolars were used. All specimens were sectioned mesio-distally. All specimens were challenged by a demineralization solution (pH4.5) for 4 days. The specimens were divided into 4 groups: (Bioglass), (Fluoride 4-minutes), (Fluoride 24-Hours), and (Temp) (n = 33). 10 specimens were examined by TMR (Transversal Microradiography)to test remineralization capacity of each agent. 8 specimens were assigned to determine the acid resistance of a bonded resin-enamel interface after the various treatment methods. 15 samples were assigned to determine the effect of each agent on the shear bond strength of a single bottle self-etch adhesive system. One way ANOVA was used to compare the obtained results (p < 0.05).

RESULTS

Specimens treated with 45S5 bioglass showed statistically significant reductions in (delta z) values when compared to the other three groups (p < 0.05). Treatment of demineralized enamel by fluoride prior to bonding significantly decreased shear bond strength values, however 45S5 bioglass treatment did not affect the shear bond strength of adhesive system to enamel (p < 0.05). The acid-resistance of the interface between resin-enamel was significantly improved when fluoride or bioglass were applied onto the enamel surface prior to demineralization.

CONCLUSIONS

45S5 bioglass paste has high potential to be used as a remineralizing temporary filling material.

Testing the Clinical Applicability of Resin Infiltration of Developmental Enamel Hypomineralization Lesions Using an In Vitro Model

Aim

The aim of this study is to investigate the penetration abilities of a commercially available low-viscosity resin infiltrant into developmentally hypomineralized teeth in vitro.

Materials and methods

Four extracted third molars of a 17-year-old patient with signs of developmental enamel hypomineralization (discoloration, increased opacity, and surface roughness) were infiltrated with a low-viscosity resin mixed with a fluorescent dye, according to the manufacturer's standard protocol. Four extracted molars with sound enamel or showing only initial fissure caries were used as a control group. Specimens were embedded in polymethylmethacrylate, and grindings were prepared. High-resolution projectional radiography of the grindings was performed, and, for one specimen, quantitative micro-computed tomography was used to measure hydroxyapatite density in enamel and dentin lesions. After decalcification, the grindings were examined by reflected bright-field microscopy, wide-field fluorescence microscopy, and confocal laser scanning microscopy. Fluorescence micrographs were superimposed on the radiographs and analyzed correlatively.

Results

The pattern of hypo-/demineralization in enamel and dentin in developmentally hypomineralized teeth showed a good congruence with the pattern of resin infiltration. Cavitations and dentin tubules up to a depth of 2 mm beyond cavitations were filled by the infiltrant. In control teeth, the penetration of the infiltrant was limited to decalcified enamel areas (initial fissure caries).

Conclusions

In vitro infiltration of developmentally hypomineralized enamel was successful.

Clinical significance

Resin infiltration might be considered as a routine procedure in the treatment of developmentally hypomineralized teeth. Further investigations with higher sample sizes, different degrees of severity, different stages of lesion extension, and modified treatment protocols are necessary.

How to cite this article

Schnabl D, Dudasne-Orosz V, et al. Testing the Clinical Applicability of Resin Infiltration of Developmental Enamel Hypomineralization Lesions Using an In Vitro Model. Int J Clin Pediatr Dent 2019;12(2):126-132.

Molar incisor hypomineralisation (MIH) - an overview

Recent data indicates that molar-incisor hypomineralisation (MIH) is a frequently - encountered dental condition worldwide. The condition could be associated with dental complications that might affect patients' quality of life as well as create treatment challenges to dentists. The affected teeth are more prone to caries and post-eruptive enamel breakdown, therefore, it is believed that this condition might be responsible for a substantial proportion of childhood caries since the condition has high prevalence. MIH is common, and as such it should be diagnosed and managed in primary care wherever possible. Early diagnosis can lead to more effective and conservative management. This article aims to highlight different aspects related to MIH, from its prevalence to treatment options in young patients.

Adhesion to Enamel of Teeth Affected by Molar Incisor Hypomineralization: Literature Review

Background/Aim: Molar incisor hypomineralization (MIH) is a qualitative defect of systemic origin, affecting permanent first molars and often permanent incisors. The treatment modalities can include, amongst others, fissure sealants for prevention of dental caries and composite restorations. Both require adhesion to tooth structure. The aim of this study was to review the literature on the adhesion to enamel affected by MIH.

Material and Methods: A search of PupMed/Medline, ResearchGate and Google Scholar was performed and limited between 2003, when the judgement criteria for MIH were set, and 2016. Thirty-three papers were considered relevant to the subject including five in vivo and six in vitro studies. Studies involving less than ten teeth were excluded.

Results: A four-year clinical trial showed that the application of a total-etch 2-step adhesive system prior to sealant placement is superior to the etch-seal technique. Despite the high success rate of composite restorations shown in three clinical longitudinal studies, there are conflicting results over self-etch being superior to total etch adhesive systems. Pretreating the enamel surface, prior to the adhesive system, with fluoride preventive solutions could reduce the mikroleakage under orthodontic brackets. Three in vitro studies provide inconsistent data about NaOCl pretreating potentials to improve adhesion of composite restorations. Resin infiltration, prior to resin restorations, could improve the microhardness of defected enamel, which may lead to increased bond strength, especially in combination with NaOCl pretreatment.

Conclusions: Adhesion to enamel affected by molar incisor hypomeralization is inferior compared to normal enamel. Sealants applied with the etch-bond-seal technique have greater retention than with the etch-seal technique. Further research is required to provide evidence of the effectiveness of the adhesive system and pretreatment to achieve optimal bonding to MIH.

Bonding strategies for MIH-affected enamel and dentin

OBJECTIVES

Aim of the present study was to evaluate resin composite adhesion to dental hard tissues affected by molar incisor hypomineralisation (MIH).

METHODS

94 freshly extracted human molars and incisors (53 suffering MIH) were used. 68 teeth (35 with MIH) were used for μ-TBS tests in enamel and dentin, 26 (18 with MIH) for qualitative evaluation. Specimens were bonded with Clearfil SE Bond, Scotchbond Universal, and OptiBond FL. For MIH affected enamel, additional OptiBond FL groups with NaOCl and NaOCl+Icon were investigated. Beside fractographic analysis, also qualitative evaluations were performed using SEM at different magnifications as well as histological sectioning.

RESULTS

Highest μ-TBS values were recorded with dentin specimens (ANOVA, mod. LSD, p<0.05). Results were independent of adhesive and dentin substrate (p>0.05). Pre-test failures did not occur in dentin specimens. Sound enamel specimens exhibited significantly higher μ-TBS values than MIH enamel (p<0.05). The two-step self-etch adhesive (Clearfil SE Bond) and the two-step etch-and-rinse adhesive (Scotchbond Universal) showed the lowest values in affected enamel specimens (p<0.05) with most pre-test failures (p<0.05). OptiBond FL on affected enamel showed better results than Clearfil SE Bond (p<0.05). An additional pre-treatment of affected enamel with NaOCl or NaOCl and Icon did not enhance enamel bonding (p>0.05), however, it caused less pre-test failures (p<0.05). Micromorphological analyses revealed that conventional phosphoric acid etching produces a much less pronounced etching pattern in affected enamel and a porous structure as weak link for the resin-enamel bond was identified.

SIGNIFICANCE

Bonding to porous hypomineralized MIH enamel is the limiting factor in adhesion to MIH teeth. MIH-affected dentin may be bonded conventionally.

Tooth mineral density of different types of hypomineralised molars: a micro-CT analysis

AIM

This study sought to evaluate the tooth mineral density (TMD) for the different lesion types in hypomineralised first permanent molars (FPMs) and compare them to unaffected enamel in clinically sound FPMs.

DESIGN

Eighteen FPMs with varying degrees of hypomineralised enamel were grouped into brown, yellow/creamy and white lesion types. Micro-CT was used to determine the TMD for each lesion type, and for unaffected enamel at different locations in the outer, middle, and inner-third of the enamel.

RESULTS

The average TMD for brown, yellow/creamy, white and unaffected enamel was 1.79, 2.21, 2.43 and 2.46 g/cm³, respectively. Brown and yellow/creamy lesions exhibited a statistically significant difference when compared to white lesions and unaffected enamel. However, no statistical difference was evident in TMD between white lesions and unaffected enamel. The TMD increased from the outer-third to inner-third for brown and yellow/creamy lesions (p < 0.05), while in white lesions and unaffected enamel, the TMD decreased from the outer-third to inner-third (p < 0.05).

CONCLUSION

TMD was lowest for brown lesions followed by yellow/creamy lesions while the TMD for white lesions was similar to unaffected enamel.

An investigation into the effect of a resin infiltrant on the micromechanical properties of hypomineralised enamel

BACKGROUND

Resin infiltration may alter the mechanical properties of enamel hypomineralised lesions (HL); however, variable surface layer (SL) thickness may affect resin penetration.

AIMS

To determine the thickness of the SL of HL and to investigate the effect of resin infiltration on the mechanical properties of HL.

DESIGN

The thickness of the SL over HL was determined using polarised light microscopy. Etching time using 15% HCl gel to remove the SL of 52 samples was determined. Selected HL and control areas of 21 teeth were infiltrated with Icon^® resin infiltrant, and cross-sectional Knoop microhardness (KHN) measurements were recorded before and after resin infiltration.

RESULTS

Ninety-six point five per cent of HL had a detectable SL with mean thickness of 58 ± 29 μm. Application of HCl for 120 s produced a mean MIH erosion depth of 58 ± 12 μm. Eleven of 21 samples had evidence of infiltration using visual examination. The infiltrant penetrated some of the HL leading to an increase in KHN (111 ± 75 KHN) which, when compared to adjacent non-infiltrated HL (96 ± 52 KHN), was not statistically significantly different (P = 0.56).

CONCLUSIONS

There was marked variation in the SL thickness of HL. Resin infiltration of HL did not increase microhardness significantly.

Tridimensional surface roughness analysis after resin infiltration of (deproteinized) natural subsurface carious lesions

OBJECTIVES

The objectives of this study were to evaluate ex vivo the effects of resin infiltration on the areal surface roughness of natural non-cavitated proximal subsurface lesions with or without previous deproteinization and to determine differences between E2 and D1 lesions or between premolars and molars.

MATERIALS AND METHODS

Forty premolars and 40 molars with proximal carious lesions and macroscopically intact surfaces (International Caries Detection and Assessment System (ICDAS) II; code 2) were radiologically assessed and randomly allocated to four groups (with 20 E2 and 20 D1 lesions, respectively). In each group, 10 lesions were deproteinized (NaOCl; 1%) before etching (HCl; 15%) and resin infiltration (Icon). Areal surface roughness (Sa) at the most demineralized lesion part (DIAGNOdent) was evaluated topometrically before and after deproteinization, after etching, and after infiltration using focus variation 3D scanning microscopy.

RESULTS

Pretreatment with NaOCl (n = 40) had no significant effects on Sa (p = 0.208), but resulted in significantly differing Sa values between premolars and molars after etching (p = 0.011). Regarding the effects between etching and baseline, significantly differing Sa values (p = 0.0498) were found for premolars and molars (n = 40/40); Sa after resin infiltration (compared to etching) differed significantly between premolars and molars (p = 0.009). No treatment regimen lead to differences among the radiological grades (E2 vs. D1; p > 0.106).

CONCLUSIONS

Resin infiltration showed only minor effects on Sa values of etched subsurface lesions (p < 0.170) and did neither equal nor improve baseline surface roughness (p > 0.401) of the different tooth types.

CLINICAL RELEVANCE

Deproteinization should be recommended before etching and infiltration, even if surface roughness of infiltrated advanced (pre-)molar lesions will not be improved.