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.

Marginal Quality and Wear of Bulk-fill Materials for Class-II Restorations in Primary Molars.

PURPOSE: The aim of this in-vitro study was to evaluate the marginal integrity and wear of eight bulk-fill materials in comparison to a compomer in Class-II cavities in primary molars after thermomechanical loading (TML). MATERIALS AND METHODS: Prepared Class-II cavities in 72 extracted primary molars were filled with eight bulk-fill materials. A compomer served as the control group. After water storage (incubator, 28 days, 37°C), samples were subjected to TML (2500 thermal cycles 5°C/55°C; 100,000 load cycles, 50 N, 1.67 Hz). Before and after TML, replicas were made which were used for both SEM analysis of marginal integrity and 3-D wear analysis. Statistical analysis was performed using Kruskal-Wallis and Wilcoxon tests (p < 0.05). RESULTS: A significant reduction in perfect margins was observed for all groups, while marginal gap formation increased (Wilcoxon test, p < 0.02) for all groups but the compomer. Significant interindividual differences were observed between the tested materials regarding marginal integrity (Kruskal-Wallis test, p < 0.05). Wear analysis revealed no significant differences between groups (Kruskal-Wallis test, p > 0.05). CONCLUSION: Some of the bulk-fill materials investigated here achieved better results than the compomer and should be further evaluated clinically.

A cross-sectional survey on knowledge and attitudes of Greek dentists regarding molar incisor hypomineralisation diagnosis and treatment.

BACKGROUND: Molar Incisor Hypomineralisation (MIH) remains a challenge for clinicians underlining the gap in the literature regarding the condition. The study aimed to record knowledge and attitudes of Greek dentists regarding diagnosis and treatment of MIH and correlate findings with non-dental characteristics. METHODS: It is a cross-sectional study based on a questionnaire consisting of 37 multiple-choice questions. Data regarding diagnosis, aetiopathogenesis, and clinical management of MIH were collected from active members of three Greek Dental Associations. Chi-square and student's t-test were used to correlate responses with practitioners' characteristics and odds ratios calculated to evaluate differences on treatment of MIH-affected teeth (p < 0.05). RESULTS: From the 360 participants (response rate = 94%), 185 were general dental practitioners (GDPs) and 175 dental specialists (59 paediatric dentists (PDs), 38 orthodontists and 78 of other specialties).MIH was commonly encountered as a clinical problem, with GDPs reporting genetics and fluoride intake as common aetiological factors at significantly higher percentages as compared to PDs (p < 0.05). Permanent molars and incisors (44%) were the teeth most commonly affected, with yellow/brown demarcated opacities (68%) the most common clinical feature with PDs reporting them in a significantly higher percentage (p < 0.05). Dentists with specialisation, dentists that treat > 10 children per week and children with MIH-affected teeth had a 2-5.5 times greater probability to report difficulty achieving sufficient anaesthesia and hypersensitivity problems (p < 0.001). Agreement between GDPs' and dental specialists' views was found on less invasive treatment of anterior lesions. Non-PDs reported bulk-fill restorations and onlays as the ideal treatment of severely-affected posterior teeth, as compared to PDs that preferred preformed metal crowns (p < 0.05). Multivariate logistic regression analysis revealed that the age of the clinician, years of experience and number of children treated per week were the factors significantly associated with the decision for the treatment of only severely-affected posterior MIH teeth. CONCLUSIONS: Most participants had encountered MIH-affected teeth in their clinical practice and were able to recognize main aetiological factors and clinical findings related to the condition. Nevertheless, their knowledge regarding treatment is limited.

Damping Behaviour and Mechanical Properties of Restorative Materials for Primary Teeth.

The energy dissipation capacity and damping ability of restorative materials used to restore deciduous teeth were assessed compared to common mechanical properties. Mechanical properties (flexural strength, modulus of elasticity, modulus of toughness) for Compoglass F, Dyract eXtra, SDR flow, Tetric Evo Ceram, Tetric Evo Ceram Bulk Fill, and Venus Diamond were determined using a 4-point bending test. Vickers hardness and Martens hardness, together with its plastic index (ηITdis), were recorded using instrumented indentation testing. Leeb hardness (HLD) and its deduced energy dissipation data (HLDdis) were likewise determined. The reliability of materials was assessed using Weibull analysis. For common mechanical properties, Venus Diamond always exhibited the significantly highest results and SDR flow the lowest, except for flexural strength. Independently determined damping parameters (modulus of toughness, HLDdis, ηITdis) invariably disclosed the highest values for SDR flow. Composite materials, including SDR flow, showed markedly higher reliabilities (Weibull modulus) than Compoglass F and Dyract eXtra. SDR flow showed pronounced energy dissipation and damping characteristics, making it the most promising material for a biomimetic restoration of viscoelastic dentin structures in deciduous teeth. Future developments in composite technology should implement improved resin structures that facilitate damping effects in artificial restorative materials.

Clinical Effectiveness of Restorative Materials for the Restoration of Carious Primary Teeth: An Umbrella Review.

Since untreated dental caries remain a worldwide burden, this umbrella review aimed to assess the quality of evidence on the clinical effectiveness of different restorative materials for the treatment of carious primary teeth. A literature search in electronic bibliographic databases was performed to find systematic reviews with at least two-arm comparisons between restorative materials and a follow-up period ≥12 months. Reviews retrieved were screened; those eligible were selected, and the degree of overlap was calculated using the 'corrected covered area' (CCA). Data were extracted and the risk of bias was assessed using the ROBIS tool. Fourteen systematic reviews with a moderate overlap (6% CCA) were included. All materials studied performed similarly and were equally efficient for the restoration of carious primary teeth. Amalgam and resin composite had the lowest mean failure rate at 24 months while high-viscosity and metal-reinforced glass ionomer cements had the highest. At 36 months, high-viscosity glass ionomer cements showed the highest failure rate with compomer showing the lowest. Most reviews had an unclear risk of bias. Within the limitations of the review, all materials have acceptable mean failure rates and could be recommended for the restoration of carious primary teeth.

Caries Experience and Increment in Children Attending Kindergartens with an Early Childhood Caries Preventive Program Compared to Basic Prophylaxis Measures-A Retrospective Cohort Study.

Dental caries constitutes a public health challenge. As preventive strategies are desirable, this retrospective cohort study aimed to assess the caries experience and increment in children attending kindergartens with an early childhood caries (ECC) preventive program (intervention group, IG) compared to basic prophylaxis measures (control group, CG) located in areas of different socioeconomic status (SES) within Marburg (Germany). The long-term caries experience (2009−2019) of these 3−5-year-old kindergarten children was evaluated. For the caries increment, dental records of 2019 were screened for the availability of a minimum of two dental examinations at least 8 months apart. Caries was scored according to the WHO criteria (dmf−t). The data were split by observation period (300−550 and >550 days). Overall, 135 children (Ø 3.7 years) attended IG, and 132 children (Ø 3.6 years) attended CG. After 300−550 days, no significant differences were found between both groups regarding mean caries increment and experience (p > 0.05). After >550 days, IG with low SES exhibited a high caries experience. Fluoride varnish applications could not reduce the caries increment compared to CG in the short-term but slightly decreased the long-term caries experience. Comprehensive ECC prevention measures actively involving parents are needed to overcome the caries burden.

Hypersensitivity relief of MIH-affected molars using two sealing techniques: a 12-week follow-up.

OBJECTIVES: The aim of this study was to compare the efficacy in reducing hypersensitivity in molar incisor hypomineralization (MIH)-affected molars immediately and over 12 weeks after sealing using two different materials (composite and glass ionomer). Furthermore, the retention rates of both materials were analyzed. METHODS: Thirty-nine children with two MIH-affected molars showing hypersensitivity and non-occlusal breakdowns were included. Hypersensitivity was assessed with an evaporative (air) stimulus. Both teeth were sealed by two calibrated operators using a split-mouth design with either Clinpro Sealant in combination with Scotchbond Universal (C) or Ketac Universal (K), respectively. Clinical pain assessments (Schiff Score Air Sensitivity Scale [SCASS], Visual Analog Scale [VAS]) were made at baseline ("pre"), immediately after treatment ("post"), and after 1, 4, 8, and 12 weeks. Paired t tests were calculated in each group between baseline and all other time points. RESULTS: Thirty-eight children with 76 molars completed all stages of the study. Regardless of the material used, the application of the sealant decreased hypersensitivity significantly immediately as well as throughout the 12-week recalls (all p values < 0.001). We found no statistically significant difference among both materials chosen in any of the time points evaluated. Furthermore, retention of both materials was comparable in both groups. CONCLUSIONS: Both sealant materials were able to reduce hypersensitivity successfully immediately and throughout the 12-week follow-up. Furthermore, their performance was similar in terms of retention. CLINICAL RELEVANCE: Hypersensitivity can be a major complaint in patients with MIH. This is the first study evaluating hypersensitivity relief of MIH-affected molars using two sealing techniques.

Long-term microtensile bond strength of self-etch adhesives and influence of 7-s phosphoric acid etching on adhesion of a 3-step etch-and-rinse adhesive to the dentine of primary teeth.

BACKGROUND: The immediate microtensile bond strength (µTBS) of self-etch (SE) adhesives to primary dentine is promising, but evidence about the durability is scarce. AIM: To assess the long-term µTBS of SE adhesives to primary dentine and to examine the effect of 7-s etching on µTBS of a 3-step etch-and-rinse (ER) adhesive. DESIGN: The enamel of 115 caries-free human primary teeth was ground flat, and bonding was performed according to group assignment: G-aenial™ Bond/GC [GB], Clearfil™ SE Bond/Kuraray [CS], OptiBond™ XTR/Kerr [OX], Scotchbond™ Universal/3M™ [SU], Prime&Bond® NT™/Dentsply [PB], and OptiBond™ FL/Kerr [OF]. After storage (24 h, 6 mos., 12 mos.), 1,762 beams were cut for µTBS testing. Fracture analysis was performed using light/fluorescence microscopy. Resin-dentine interfaces were exemplarily analyzed using SEM. RESULTS: After 24 h, OX and SU showed significantly higher estimated mean µTBS than GB, which exhibited the lowest µTBS at all stages (p < .05). µTBS within each adhesive group showed slight variations over time (p > .05). OF_SE produced acceptable µTBS. Etching increased the mean immediate µTBS for OF (p > .05) and the percentage of cohesive fractures. CONCLUSIONS: SE adhesives achieved durable µTBS to primary dentine. 7-s etching may improve the immediate µTBS of a 3-step ER adhesive.

Post-Fatigue Fracture and Marginal Behavior of Endodontically Treated Teeth: Partial Crown vs. Full Crown vs. Endocrown vs. Fiber-Reinforced Resin Composite.

OBJECTIVES: To investigate in vitro post-fatigue fracture behavior of endodontically treated molars having been differently restored. METHODS: A total of 120 extracted human molars were used. A total of 120 specimens in 14 test groups and one control group (n = 8) were root canal treated. After postendodontic sealing and build-up (AdheSE Universal, SDR), additional MOD preparations were cut. Postendodontic restorations were: Direct restorations (Tetric EvoCeram BulkFill bonded with AdheSE Universal and EverX Posterior/Essentia bonded with G-Premio Bond; as filling (F) or direct partial crown (DPC) after reducing the cusps 2 mm; indirect adhesive restorations (partial crown/PC vs. full crown/FC): e.max CAD, Celtra Duo, both luted with Variolink Esthetic; indirect zirconia restorations (partial crown/PC vs. full crown/FC), luted with RelyX Unicem 2; indirect non-bonded cast gold restorations (partial crown/PC vs. full crown/FC; Degunorm), luted with Ketac Cem. Before and after 300,000 thermocycles (5/55 °C) and 1.2 Mio. A total of 100 N load cycles, replicas were analyzed under a SEM for marginal quality in enamel and dentin (where applicable) and finally, specimens were loaded until fracture. RESULTS: In direct groups, there was no difference between RC and FRC in fracture strength (p > 0.05); however, direct partial crowns showed higher post-fatigue fracture resistance. Regarding marginal quality, intracoronal FRC restorations exhibited more gap-free margins in enamel than RC. In the indirect groups, there was no significant difference between partial and full crowns in any of the adhesively luted ceramic groups regarding post-fatigue fracture resistance. Zirconia partial crowns exhibited significantly lower marginal quality in enamel. Indirect groups performed significantly better than direct groups in fracture resistance. Within the indirect restorations, both cast gold groups and zirconia full crowns exhibited the highest fracture resistance being superior to control teeth. SIGNIFICANCES: Within the limits of this in vitro investigation, it can be concluded that any kind of indirect restoration with cusp replacement is suitable for ETT restoration when a certain cavity extension is exceeded. All indirect restorations, i.e., endocrowns, partial crowns, and full crowns showed a promising performance after in vitro fatigue-loading.

Microleakage of pit and fissure sealings placed after enamel conditioning with phosphoric acid or with self-etching primers/adhesives.

BACKGROUND: It is still not fully understood what pretreatment is best for achieving maximum tightness for pit and fissure sealings (PFS). AIM: This study investigated microleakage of PFS placed after etching with phosphoric acid or after the application of self-etching primers/adhesives (SEPA). DESIGN: 131 third molars were assigned to ten groups. In Hel-P, Helioseal® was applied after phosphoric acid etching. In the other groups, SEPA were used (Dyr-AP: Adper™ Prompt™ L-Pop™, Dyract® Seal; Bea: BeautiSealant Primer and Paste; Hel-Exp: Experimental primer, Helioseal®; Hel-Cl: Clearfil™ SE Bond1 , Helioseal®). Specimens were stored in distilled water at 37°C (28 days), followed by 3500 thermocycles and staining with 5% methylene blue (M) or 5% silver nitrate (S). After methylene blue staining and sectioning, microleakage was assessed light microscopically. During silver nitrate staining, specimens were dissolved by 32% HCl and remaining PFS were evaluated under a SEM. RESULTS: Tightness, percentage of penetrated area, and maximum dye penetration were best for Hel-P and Hel-Cl (p < 0.05). CONCLUSIONS: Phosphoric acid etching of enamel and Clearfil™ SE Bond resulted in the best sealing quality. Methylene blue staining allowed the evaluation of more criteria (fissure shape, voids, sealant penetration depth) compared to silver nitrate.

Changes in oral health-related quality of life after treatment of hypersensitive molar incisor hypomineralization-affected molars with a sealing.

OBJECTIVES: The aim of this study was to investigate the changes in oral health-related quality of life (OHRQoL) before and after treatment of hypersensitive molars affected by molar incisor hypomineralization (MIH) with a sealing. METHODS: Thirty-eight children with two MIH-affected molars showing hypersensitivity and non-occlusal breakdowns were included. Hypersensitivity was assessed with an evaporative (air) stimulus. Two affected teeth were sealed by two calibrated operators using a split-mouth design: Clinpro Sealant in combination with Scotchbond Universal, and Ketac Universal (3M), respectively. OHRQoL was measured using the German version of the CPQ8-10 (CPQ-G8-10) at baseline, and after 1, 4, 8, and 12 weeks, respectively. RESULTS: The CPQ total score decreased significantly from a mean of 14.7 (±5.9) to 6.4 (±4.7) (p < 0.001) 1 week after treatment revealing improved OHRQoL. After 12 weeks, OHRQoL improved again proven by a decreased mean score of 2.7 (±3.2). CONCLUSIONS: Sealing of hypersensitive MIH-affected molars revealed a significant improvement of OHRQoL immediately and throughout the 12-week follow-up. CLINICAL RELEVANCE: Hypersensitivity can be a major complaint in patients with MIH. This is the first study evaluating the effect of sealing on OHRQoL in affected patients.

Class II resin composite restorations-tunnel vs. box-only in vitro and in vivo.

PURPOSE: In a combined in vitro/in vivo approach, tunnel vs. box-only resin composite restorations should be evaluated using thermomechanical loading (TML) in vitro and a restrospective clinical trial in vivo. MATERIALS AND METHODS: For the in vitro part, box-only and tunnel cavities were prepared in 32 extracted human third molars under simulated intraoral conditions in a phantom head. Specimens were randomly assigned to four groups (n = 8; 16 box-only/16 tunnel) and received bonded resin composite restorations with Amelogen Plus (box A/tunnel A) or lining with Ultraseal and Amelogen plus (box B/tunnel B) both bonded using PQ1 (all Ultradent). Specimens were subjected to a standardized aging protocol, 1-year water storage (WS) followed by TML (100,000 × 50 N; 2500 × + 5/+ 55 °C). Initially and after aging, marginal qualities were evaluated using replicas at × 200 magnification (SEM). For the corresponding in vivo observational study, 229 patients received 673 proximal resin composite restorations. From 371 tunnel restorations, 205 cavities were filled without flowable lining (tunnel A), and 166 tunnels were restored using UltraSeal as lining (tunnel B). A total of 302 teeth received conventional box-only fillings. Restorations were examined according to modified USPHS criteria during routine recalls up to 5 years of clinical service. RESULTS: In vitro, all initial results showed 100% gap-free margins when a flowable lining was used. Tunnels without lining exhibited some proximal shortcomings already before TML and even more pronounced after TML (p < 0.05). After TML, percentages of gap-free margins dropped to 87-90% in enamel with lining and 70-79% without lining (p < 0.05). In vivo, annual failure rates for box-only were 2.2%, for tunnel A 6.1%, and for tunnel B 1.8%, respectively (p < 0.05). Tunnels had significantly more sufficient proximal contact points than box-only restorations (p < 0.05). Flowable lining was highly beneficial for clinical outcome of tunnel-restorations (p < 0.05). CONCLUSIONS: With a flowable lining, tunnel restorations proved to be a good alternative to box-only resin composite restorations. CLINICAL RELEVANCE: Class II tunnel restorations showed to be a viable alternative for box-only restorations, however, only when flowable resin composite was used as adaptation promotor for areas being difficult to access.

Secondary caries formation with a two-species biofilm artificial mouth.

OBJECTIVES: The present study aimed to establish Lactobacillus casei in a completely automated Streptococcus mutans-based artificial mouth model and to investigate secondary caries inhibiting properties of glass ionomer cements / resin composite groups in vitro. METHODS: Sixty extracted, caries-free human third molars were used for preparation of standardized class-V-cavities. Specimens were restored with a resin-modified (Photac Fil; PF) as well as a conventional glass ionomer cement (Ketac Molar; KM) and one resin composite bonded with and without conduction of etch-and-rinse technique (Prime&Bond NT, Ceram X mono; C+ERT, C). Following an incubation in distilled water for 28d at 37°C, specimens were exposed to 10,000 thermocycles (+5 °C/+55°C). A completely automated S. mutans-based (DSM No.: 20523) artificial mouth model was extended by establishment of L. casei (DSM No.: 20021). During microbiological loading, demineralization (4h/d) was caused by acid production resulting from bacterial glycolysis and artificial saliva was used for remineralization (20h/d). For quantitative margin analysis under am SEM, epoxy replicas were produced from impressions taken after thermocycling and after microbiological loading. Specimens were cut in half perpendicularly to restoration surfaces and demineralization depths at restoration margins and in 500µm distance from margins were evaluated by means of a fluorescence microscope (FITC filter). RESULTS: After microbiological loading, overall demineralization depths in enamel at restoration margin (EM) and in 500µm distance (ED) as well as in cementum/dentin at restoration margin (DM) and in 500µm distance (DD) were measured as follows (µm±SD): PF: EM 42±15, ED 60±17, DM 83±18; DD 127±16; KM: EM 46±22, ED 62±17, DM 104±21, DD 143±28; C+ERT: EM 67±19, ED 61±17, DM 165±31, DD 176±35; C: EM 65±23, ED 64±17, DM 161±27, DD 166±33. For the glass ionomer cements, the overall demineralization depths at restoration margins were significantly lower than in 500µm distance from margins (T-test, p<0.05). Especially at restoration margins in cementum/dentin, the resin composite groups showed significantly larger overall demineralizations than the glass ionomer cements (ANOVA, mod. LSD, p<0.05). Decreases of marginal quality were detected in all groups after microbiological loading (Friedman-test, p<0.05). SIGNIFICANCE: The refined experimental setup was suitable for production of artificial secondary caries-like lesions. Glass ionomer cements as fluoride-releasing materials may show an inhibition of secondary caries formation to a certain extent.