Bond strength and marginal adaptation of resin composites and correlations with clinical results.

OBJECTIVES: Due to innumerable confounding factors and a high number of types and brands of dental restorative materials, the clinical performance of restorative materials are sought predicted by various in vitro tests. However, only few such tests have been found to correlate well with clinical findings. Thus, the present study determined the in vitro dentin bond strength and marginal adaptation of Class II restorations and correlated the results to their clinical outcomes. METHODS: Dentin bond strength (µTBS and µSBS) and marginal gap formation of Class II restorations (replica technique and SEM) were measured after 24 h and 6 m water storage using eight combinations of adhesive and resin composite. Clinical outcomes (mean survival time, Hazard Ratio, annual failure rate; n = 10.695) were gained from a data set of a retrospective multicenter study of direct restorations. RESULTS: Significant differences were found for dentin bond strength and marginal gap formation between the restorative material groups, and negative effects of long-term storage were observed. µTBS correlated significantly with certain clinical outcomes of Class I restorations, while µSBS correlated with certain clinical outcomes of Class II, III, IV and V restorations. Marginal gap formation in enamel and number of paramarginal fractures correlated with certain clinical outcomes of Class II restorations. SIGNIFICANCE: Using the same restorative materials in vitro as in vivo, gave significant, but weak correlations between in vitro bond strength or marginal adaptation and clinical outcomes, lending support to the use of in vitro tests in early stages of material selection.

Success and complication rates of non-precious alloy telescopic crowns in a general dental practice.

OBJECTIVES: This retrospective, single-center, practice-based cohort study aimed to analyze factors associated with the success of removable partial dentures retained by telescopic crowns (TRPD). MATERIALS AND METHODS: TRPD which were placed in a single practice of a practice-based research network were analyzed. Data from 139 patients (age (SD): 66 (11) years; 66 female) with 174 TRPD including 488 non-precious alloy telescopic crowns (TC) between 2004 and 2016 were included. TC without any technical complication were considered as successful, and as survived, if they were still in function at the last check-up. Multilevel Cox proportional hazard models were used to evaluate the association between clinical factors and time until failure. RESULTS: Within a mean follow-up period (SD) of 4.2 (3.3) years (min-max: 1 day-12 years), 372 (76%) TC (AFR5years,TC-level: 5.0%) as well as 136 (87%) TRPD (AFR5years,TRPD-level: 5.1%) ("worst-case scenario") and 150 (86%) TRPD (AFR5years,TRPD-level: 3.4%) ("best-case scenario") were considered as successful. The main failure types were recementation (n = 39), endodontic treatment (n = 36), and extraction (n = 35). TC in male patients showed 1.6 times higher risk for failure than in female patients (95%CI: 1.1-2.4; p = 0.023). TC on premolars showed 2.2 times higher risk for failure than on incisors (95%CI: 1.1-5.0; p = 0.023) and TC in dentures with ≤ 3TC showed 2.1 times higher risk for failure than TC in dentures with > 3TC (1.3-3.4; p = 0.042). Furthermore, TC on the most distal tooth in an arch showed 2.4 times higher risk for failure than TC on a more mesial tooth (1.5-3.8; p < 0.001). CONCLUSION: For removable partial dentures retained by telescopic crowns, high success rates could be found after up to 12 years. Patient-level and tooth-level factors were significantly associated with failure. CLINICAL RELEVANCE: For removable partial dentures retained by telescopic crowns, high success rates could be found after up to 12 years. Patient-level and tooth-level factors were significantly associated with failure.

Effect of whitening products on sound enamel and on artificial caries lesions during a cariogenic challenge.

OBJECTIVE: To investigate the effect of fluoride-containing whitening products on sound enamel and on artificial caries lesions during a cariogenic challenge. MATERIALS AND METHODS: Bovine enamel specimens (n = 120) with three areas [non-treated sound enamel (NSE), treated sound enamel (TSE), and treated artificial caries lesion (TACL)] were randomly assigned to the four groups: whitening mouthrinse (WM: 2.5% hydrogen peroxide-100 ppm F-), placebo mouthrinse (PM: 0% hydrogen peroxide-100 ppm F-), whitening gel (WG: 10% carbamide peroxide-1130 ppm F-), and deionized water (negative control; NC). The treatments (2 min for WM, PM, and NC, and 2 h for WG) were carried out during a 28-day pH-cycling model (6 × 60 min demineralization/day). Relative surface reflection intensity (rSRI) and transversal microradiography (TMR) analyses were performed. Fluoride uptake (surface and subsurface) was measured in additional enamel specimens. RESULTS: For TSE, a higher value of rSRI was observed in WM (89.99% ± 6.94), and a greater decrease in rSRI was observed for WG and NC, and no sign of mineral loss was verified for all groups (p > 0.05). For TACL, rSRI significantly decreased after pH-cycling for all experimental groups with no difference between them (p < 0.05). Higher amounts of fluoride were found in WG. WG and WM exhibited intermediate values of mineral loss, similar to PM. CONCLUSIONS: The whitening products did not potentialize the enamel demineralization under a severe cariogenic challenge, and they did not exacerbate mineral loss of the artificial caries lesions. CLINICAL RELEVANCE: Low concentrated hydrogen peroxide whitening gel and mouthrinse containing fluoride do not intensify the progression of caries lesions.

Evaluation of the masking efficacy of caries infiltration in post-orthodontic initial caries lesions: 1-year follow-up.

OBJECTIVES: This study aimed to qualitatively and quantitatively assess the masking efficacy and color stability of resin infiltration on post-orthodontic ICL after 1 year. MATERIALS AND METHODS: In 17 adolescents, 112 ICL (ICDAS-1: n = 1; ICDAS-2: n = 111) in 112 teeth were treated by resin infiltration (Icon, DMG) 3 to 12 months after bracket removal. The etching procedure was performed up to 3 times. Standardized digital images were taken before treatment (T0), 7 days (T7) and 12 months (T365) after treatment. Outcomes included the evaluation of the color differences between infiltrated and healthy enamel at T0, T7, and T365 by quantitative (colorimetric analysis (ΔE), ICDAS scores) and qualitative methods (5-point Likert scale (deteriorated (1), unchanged (2), improved, but not satisfying (3), improved and no further treatment required (4), completely masked (5)).) Differences between time points were analyzed by using Friedman test (ΔΕ) and chi-square tests (ICDAS). RESULTS: The median color difference (25th/75th percentiles) between carious and healthy enamel at baseline (ΔΕ0) was 10.2(7.7/13.6). A significant decrease was observed 7 days after treatment (ΔΕ7 = 3.1(1.8/5.0); p < 0.001; ICDAS; p < 0.001). No significant changes based on ΔΕ (p = 1.000), and ICDAS grade (p = 0.305) were observed between T7 and T365 (ΔΕ12 = 3.4 (1.8/4.9)). Furthermore, at T365 four experienced dentists classified 55% and 39% of the lesions as "improved and no further treatment required" and "completely masked," respectively (Fleiss kappa: T365 = 0.851 (almost perfect)). CONCLUSION: Resin infiltration efficaciously masked post-orthodontic ICL 7 days and 12 months after treatment. These results for most of the teeth could not only be observed by quantitative but also by qualitative analysis. CLINICAL RELEVANCE: Resin infiltration efficaciously masks post-orthodontic initial carious lesions. The optical improvement can be observed directly after treatment and remains stable for at least 12 months.

Systematic review and meta-analysis on physical barriers to prevent root dentin demineralization.

The present review systematically analyzed in vitro and in situ studies investigating physical diffusion barriers (sealants, desensitizer or adhesives) to prevent the development or the progression of root (dentin) demineralization. Three electronic databases (PubMed-Medline, CENTRAL, Ovid-EMBASE) were screened for studies from 1946 to 2022. Cross-referencing was used to identify further articles. Article selection and data abstraction were done in duplicate. Languages were not restricted. The type of outcome was not restricted, and their mean differences (MD) were calculated using fixed- or random-effects models. Risk of Bias was graded using Risk of Bias 2.0 tool. From 171 eligible studies, 34 were selected for full-text analysis evaluating 69 different materials, and 17 studies-still evaluating 36 different materials-were included (3 in situ and 14 in vitro). Ten studies evaluated desensitizers; 8 adhesives; and 1 infiltration. Meta-analyses were possible for all 17 studies. Meta-analyses revealed that lesion depth after no treatment was significantly higher than after the application of single-step adhesives (MD[95%CI] = - 49.82[- 69.34; - 30.30]) and multi-step adhesives (MD[95%CI]=-60.09 [-92.65, -27.54]). No significant differences in the lesion depth increase between single- and multi-step adhesives could be observed (MD[95%CI]=30.13 [-21.14, 81.39]). Furthermore, compared to no treatment the increase of the lesion depth was significantly hampered using desensitizers (MD[95%CI] = - 38.02[- 51.74; - 24.31]). Furthermore, the included studies presented unclear or high risk. A physical diffusion barrier can significantly hamper the increase of lesion depth under cariogenic conditions. Furthermore, multi-step adhesives seem not to be more effective than single-step adhesives. However, this conclusion is based on only few in vitro and in situ studies.

Longevity of immediate rehabilitation with direct metal-wire reinforced composite fixed partial dentures.

OBJECTIVES: This study aimed to analyze the longevity of direct metal-wire reinforced composite fixed partial dentures (MRC-FPD) and factors influencing their survival and success. METHODS: Within one private practice 513 MRC-FPD were directly applied. The preparation of a proximal cavity in abutment teeth was not limited. MRC-FPD were reinforced by one to three metal-wires. At the last follow-up MRC-FPD were considered successful, if they were still in function without any need of therapy. MRC-FPD were considered as survived, if they were repaired or replaced. Multi-level Cox proportional hazard models were used to evaluate the association between clinical factors and time. RESULTS: Mean follow-up period (range) was 59(2-249) months. Seventy-three bridges did not survive (cumulative survival rate(CSR):86%) and further 129 bridges had received a restorative follow-up treatment (CSR:61%). AFR was 2.2% for survival and 8.6% for success. In multivariate analysis MRC-FPD with> 1 wire showed a up to 2.3x higher failure rate than MRC-FPD with one wire(p ≤ 0.023). Dentist's experience in designing MRC-FDP (p ≤ 0.017), patient's caries risk (p ≤ 0.040) and bruxism (p = 0.033) significantly influenced the failure rate: the more experience, the lower caries risk and bruxism, the lower the failure rate. SIGNIFICANCE: For directly prepared metal-wire reinforced composite bridges high survival and moderate success rates were observed. MRC-FPD might, thus, be an immediate, short- and medium-term solution for replacing missing teeth. However, several factors on the levels of practice (dentist's experience in designing MRC-FDP), patient (bruxism, caries risk) and restoration (number of wires) were identified as significant predictors for the failure rate. The study was registered in the German Clinical Trials Register (DRKS-ID: DRKS00021576).

Efficacy of sealants and bonding materials during fixed orthodontic treatment to prevent enamel demineralization: a systematic review and meta-analysis.

To analyse clinical studies investigating coating agents such as sealants and other bonding materials to prevent the initiation or inhibit the progress of white spot lesions (WSL) during orthodontic treatment with fixed appliances. Electronic databases (Pubmed, CENTRAL, EMBASE) were screened for studies. No language restrictions were applied. Study selection, data extraction and quality assessment were done in duplicate. Primary outcome included assessment of WSL with visual-tactile assessment and/or laser fluorescence measurements. Twenty-four studies with 1117 patients (age: 11-40 years) and 12,809 teeth were included. Overall, 34 different sealants or bonding materials were analysed. Fourteen studies analysed fluoride and 14 studies non-fluoride releasing materials. Meta-analysis for visual tactile assessment revealed that sealants significantly decreased the initiation of WSL compared to untreated control (RR [95%CI] = 0.70 [0.53; 0.93]; very low level of evidence). Materials releasing fluoride did not decrease initiation of WSL compared to those with no fluoride release (RR [95%CI] = 0.84 [0.70; 1.01]; very low level of evidence). For laser fluorescence measurements no meta-analysis could be performed. The use of sealants seems to be effective in preventing the initiation of post-orthodontic WSL. Furthermore, there is no evidence supporting that fluoride-releasing sealants or bonding materials are more effective than those without fluoride release. No gold standard prevention strategy to prevent WSL during treatment with fixed orthodontic appliances has been established yet. However, based on only a limited number of studies the use of sealants seems to be effective in preventing the initiation of post-orthodontic WSL.

Root canal morphology of the mandibular second premolar: a systematic review and meta-analysis.

BACKGROUND: The aim of this paper was to systematically review the root canal configuration (RCC) and morphology literature of the mandibular second premolar (Mn2P). METHODS: Systematic research of five electronic databases was performed to identify published literature concerning the root canal configuration (RCC) of the Mn2P up through July 2020. Studies were selected according to predefined search terms and keywords inclusion criteria: "root canal configuration", "root canal system", "root canal morphology", "mandibular second premolar", "mandibular premolars", "morphology" and "anatomy". Further possible studies were identified by cross-referencing and screening the bibliographies of the selected articles. RESULTS: From 1622 retrieved studies, 44 studies investigating the internal morphology of 17,839 Mn2Ps were included. Most examined Mn2Ps were single-rooted (89.5-100%); two-rooted (0.1-8%) and three-rooted (0.1-3.5%) Mn2Ps at lower frequency. Most frequent RCCs reported were 1-1-1/1 (55.3-99.6%) followed by 1-1-2/2 (0.5-57%) and 2-2-2/2 (0.6-18%). The meta-analysis of seven studies demonstrated that a significantly higher number of RCC type 1-2-1/1 (OR [95%CI] = 2.05 [1.27, 3.33]) and 2-2-2/2 (OR [95%CI] = 2.32 [0.65, 8.63]) were observed in male than in female patients. CONCLUSIONS: Different RCC research methods have been reported. Whereas clearing and radiographs were commonly used in the past, CBCT has been prevalent in recent years. A globally high frequency of a 1-1-1/1 RCC in the Mn2P has been reported. Nevertheless, the probability that different, more complicated RCCs can appear in Mn2Ps should not be underestimated and, thus, should be taken into consideration when making decisions during an endodontic treatment.

Proximal caries infiltration - Pragmatic RCT with 4 years of follow-up.

OBJECTIVES: Efficacy of proximal caries infiltration to arrest lesion progression has been shown in university settings, but only once in a practice-based pragmatic design with a follow-up of 18 months. The aim of this randomized split-mouth placebo-controlled study was to follow-up this cohort for 3 years and those with high caries risk for 4 years. METHODS: Originally, in 87 children and young adults pairs of 238 proximal caries lesions, radiographically extending into inner half of enamel (E2) or outer third of dentin (D1), were randomly allocated to two groups: infiltration (Icon; DMG) or mock (control) treatment by five dentists in four private practices. All subjects received risk-related instructions for diet, flossing and fluoridation. The primary outcome was radiographic lesion progression (pairwise comparison) evaluated by two evaluators independently being blinded to treatment allocation. RESULTS: After 36 months [mean (SD): 1152 (166) days] 165 lesion pairs in 64 patients as well as after 48 months [mean (SD): 1496 (121) days] 71 lesion pairs in 20 high caries risk patients could be re-evaluated clinically as well as radiographically using individualized bitewing holders as at baseline. No adverse events could be observed. After 36 months, progression was recorded in 23/165 test (14%) and 64/165 control lesions (39%) [McNemar/Obuchowski test; p<0.001; relative risk reduction (CI95%): 64 (45-77%)]. After 48 months lesion progression was recorded in 13/71 test (18%) and 34/71 control lesions (48%) [p = 0.003; relative risk reduction (CI95%): 62 (34-78%)] of high caries risk patients. CONCLUSIONS: It can be concluded that also in a practice-setting proximal caries infiltration is more efficacious in reducing lesion progression compared with individualized non-invasive measures alone over a period of four years.

Efficacy of resin infiltration to mask post-orthodontic or non-post-orthodontic white spot lesions or fluorosis - a systematic review and meta-analysis.

OBJECTIVE: The present review systematically analyzed clinical studies investigating the efficacy of resin infiltration on post-orthodontic or non-post-orthodontic, white spot lesions (WSL), or fluorosis. MATERIALS: Five electronic databases (Central, PubMed, Ovid MEDLINE, Ovid EMBASE, LILACS) were screened. Article selection and data abstraction were done in duplicate. No language or time restrictions were applied. Outcomes were visual-tactile or DIAGNOdent measurements. RESULTS: Eleven studies with 1834 teeth being affected in 413 patients were included. Nine studies were randomized control trials, one a prospective cohort study, and one had an unclear study design. Meta-analysis could be performed for "resin infiltration vs. untreated control," "resin infiltration vs. fluoride varnish," and "resin infiltration without bleaching vs. resin infiltration with bleaching." WSL being treated with resin infiltration showed a significantly higher optical improvement than WSL without any treatment (standard mean difference (SMD) [95% CI] = 1.24 [0.59, 1.88], moderate level of evidence [visual-tactile assessment]) and with fluoride varnish application (mean difference (MD) [95% CI] = 4.76 [0.74, 8.78], moderate level of evidence [DIAGNOdent reading]). In patients with fluorosis, bleaching prior to resin infiltration showed no difference in the masking effect compared to infiltration alone (MD [95% CI] = - 0.30 [- 0.98, 0.39], moderate level of evidence). CONCLUSION: Resin infiltration has a significantly higher masking effect than natural remineralization or regular application of fluoride varnishes. However, although the evidence was graded as moderate, this conclusion is based on only very few well-conducted RCTs. CLINICAL RELEVANCE: Resin infiltration seems to be a viable option to esthetically mask enamel white spot lesions and fluorosis.

A prospective, multi-center, practice-based cohort study on all-ceramic crowns.

OBJECTIVES: The aim of this prospective, multi-center, practice-based cohort study was to analyze factors associated with the success of all-ceramic crowns. METHODS: All-ceramic crowns placed in a practice-based research network ([Ceramic Success Analysis, AG Keramik) were analyzed. Data from 1254 patients with (mostly in-office CAD/CAM) all-ceramic crowns placed by 101 dentists being followed up for more than 5 years were evaluated. At the last follow-up visit crowns were considered as successful (not failed) if they were sufficient, whereas crowns were considered as survived (not lost) if they were still in function. Multi-level Cox proportional hazards models were used to evaluate the association between a range of predictors and time of success or survival. RESULTS: Within a mean follow-up period (SD) of 7.2(2)years [maximum:15years] 776 crowns were considered successful (annual failure rate[AFR]:8.4%) and 1041 crowns survived (AFR:4.9%). The presence of a post in endodontically treated teeth resulted in a risk for failure 2.7 times lower than that of restorations without a post (95%CI:1.4-5.0;p = 0.002). Regarding the restorative material and adhesive technique, hybrid composite ceramics and single-step adhesives showed a 3.4 and 2.2 times higher failure rate than feldspathic porcelain and multi-step adhesives, respectively (p < 0.001). Use of an oxygen-blocking gel as well as an EVA instrument resulted in a 1.5-1.8 times higher failure rate than their non-use (p ≤ 0.001). SIGNIFICANCE: After up to 15years AFR were rather high for all-ceramic crowns. Operative factors, but no patient- or tooth-level factors were significantly associated with failure. The study was registered in the German Clinical Trials Register (DRKS-ID: DRKS00020271).

Efficacy of a self-assembling peptide to remineralize initial caries lesions - A systematic review and meta-analysis.

INTRODUCTION/OBJECTIVES: The present review systematically analyzed clinical studies investigating the efficacy of self-assembling peptides (SAP) to reduce initiation of or to remineralize initial caries lesions. DATA: Prospective controlled (non-)randomized clinical trials investigating the efficacy of a self-assembling peptide compared to any other (placebo) treatment or untreated/standard control. Outcomes were visual analog scale (VAS), laser fluorescence, ICDAS score or morphometric measurements. SOURCES: Three electronic databases (Central, PubMed, Ovid EMBASE) were screened. No language or time restrictions were applied.. Risk of Bias and level of evidence was graded using Risk of Bias 2.0 tool and Grade Profiler 3.6. STUDY SELECTION/RESULTS: Seven studies with 508 teeth being affected in 294 patients were included. All studies were randomized controlled trials (RCT), five with a split-mouth and two with a parallel-arm design. Meta-analysis could be performed for SAP (plus fluoride varnish (FV)) vs. no treatment (plus FV) (control treatment). Depending on the outcome after up to 12 months SAP showed a significantly higher optical improvement than the control treatment (laser fluorescence: Standardized Mean Difference (SMD)[95 %CI] = -0.87[-1.39,-0.34; VAS: Mean Difference (MD)[95 %CI] = -35.38[-43.13,-27.64]) or no significant difference could be observed (ICDAS/activity score; Relative Risk (RR)[95 %CI] = 0.6[0.21,1.74]; morphometric measurements: SMD[95 %CI] = -1.95[-4.54,0.65]). Level of evidence was very low for all 4 outcomes. Furthermore, six studies showed a high risk of bias and six studies were (partially) funded by the manufactures of the tested products. CONCLUSION: Based on a low number of clinical trials with relatively short follow up-periods and high risks of bias, self-assembling peptides may be a viable option to remineralize enamel caries. CLINICAL SIGNIFICANCE: Self-assembling peptides may be a viable option to remineralize enamel caries. However, results should be interpretated with caution due the low number of clinical trials, the short follow-up periods and the limiting grade of evidence.

Longevity of immediate rehabilitation with direct fiber reinforced composite fixed partial dentures after up to 9 years.

OBJECTIVES: This retrospective, single-center, practice-based cohort study aimed to analyze the longevity of direct fiber reinforced composite fixed partial dentures (DFRC-FPD) and to analyze factors influencing their survival and success. METHODS: Within one private practice 100 DFRC-FPD were directly applied. The preparation of a proximal cavity was limited to abutment teeth with an existing filling (minimal-invasive approach). All intact enamel surfaces were preserved (micro-invasive approach). DFRC-FPD were reinforced by fiber-splints with semi polymer network matrices (Everstick C + B©). At the last follow-up DFRC-FPD were considered successful if they were still in function without any need of therapy. DFRC-FPD were considered as survived if they were repaired or replaced. Multi-level Cox proportional hazard models were used to evaluate the association between clinical factors and time. RESULTS: Within a mean follow-up period (range) of 53 (2-109) months 7 bridges did not survive (cumulative survival rate: 93%) and further 24 bridges had received a restorative follow-up treatment (cumulative success rate: 69%). The annual failure rate was 1.6% for survival and 8.3% for success. The main failure type was fracture of the composite material (n = 30). In multivariate analysis no significant predictor could be found for success and survival. CONCLUSIONS: For directly prepared fiber reinforced composite bridges high survival and moderate success times were observed after up to nine years. Based on the present results DFRC-FPD might be an immediate, short- to medium-term solution for replacing 1 to 2 missing teeth with no or minimal tooth preparation. CLINICAL SIGNIFICANCE: Within the limitations of the present study DFRC-FPD offered an immediate, micro-/minimal-invasive, inexpensive short- and medium-term solution to replace missing teeth, even if no box-shaped proximal cavity was prepared.

Risk Factors for Failure of Direct Restorations in General Dental Practices.

The aim of this retrospective noninterventional multicenter practice-based study was to analyze factors influencing the survival of direct restorations. Records from patients who visited 5 private practices regularly were searched for the presence of direct restorations. Data were recorded from 7,858 patients with 27,407 direct restorations being detected at least 6 mo before the last recall visit. Multilevel Cox proportional hazard models were used to evaluate the association between clinical factors and time until failure. Within 228 mo, 5,493 failures could be observed. Median survival time was 207 mo. The annual failure rates were 3.8%, 4.0%, 4.6%, 4.9%, and 3.9% for class I, II, III, IV, and V restorations, respectively. Class II and IV restorations showed a 1.1-times (95% CI, 1.0 to 1.2) and 1.2-times (95% CI, 1.1 to 1.2) higher failure rate than class I restorations (P ≤ 0.029). Patients aged <20 y and >60 y showed up to a 1.4-times higher failure rate than patients aged 20 to 60 y (P ≤ 0.015). Restorations that underwent check-up twice a year or more showed a significantly higher failure rate than those that did so less than twice a year (P < 0.001). Furthermore, the dentists significantly influenced time until failure (P < 0.001). Regarding the restorative material, composites showed up to a 2.1-times longer time until failure than GIC (P ≤ 0.020). Moderate failure rates were observed for direct restorations in the private practice setting after up to 18.5 y. Within the limitations of the present study, several factors on the levels of practice (i.e., dentist), patient (i.e., age), and tooth (i.e., restorative material, restored surfaces according to the classification of Black) were significant predictors for the failure rate. Therefore, treatment decision should take into account most relevant factors (German Clinical Trials Register DRKS00015228).

Re- and demineralization characteristics of dentin depending on fluoride application and baseline characteristics in situ.

OBJECTIVES: The aim of this double-blinded, randomized, cross-over in situ study was to evaluate the re- and demineralization characteristics of sound dentin as well as highly and lowly demineralized dentin after the application of different fluoride concentrations. METHODS: In each of four experimental legs of four weeks 20 participants wore intraoral mandibular appliances containing two (highly demineralized [EH]) bovine enamel and four (lowly and highly demineralized [DL,DH]) bovine dentin specimens (n = 480). Each specimen included one sound (ST) and one demineralized lesion area (DT). The four randomly allocated treatments included the following dentifrices: fluoride-free, zinc-carbonate-nano-hydroxyapatite [nHA0], 0 ppm F- [negative control,NaF0], 1100 ppm F- as NaF [standard therapy,NaF1100] and 5000 ppm F- as NaF [positive control,NaF5000]. Differences in integrated mineral loss (ΔΔZ) and lesion depth (ΔLD) were calculated between values before and after the in situ period using transversal microradiography. RESULTS: After the in situ period specimens of nHA0 and NaF0 showed signs of demineralization, indicated by significantly lower ΔZ&LD values for EH and DL (only nHA0)(p ≤ 0.028), whereas specimens of NaF1100 and NaF5000 showed signs of remineralization, indicated by significantly higher ΔZ values for EH (only NaF5000), DL and DH (p ≤ 0.012). The correlation between ΔΔZDT/ΔΔZST and F- was moderate for EH(rDT = 0.497;rST = 0.463) and DL(rDT = 0.575;rST = 0.598) and strong for DH(rDH = 0.700;rST = 0.611)(p < 0.001). No significant differences for ΔΔZDT/ΔΔZST were observed between nHA0 and NaF0(p ≥ 0.333;ANCOVA). CONCLUSION: The present in situ model was capable to reveal a fluoride dose-response on sound, lowly and highly demineralized dentin and also enamel specimens. Furthermore, both fluoride-free dentifrices, one containing nanohydroxyapatite, did not hamper demineralization. CLINICAL SIGNIFICANCE: The present in situ model was capable to reveal a fluoride dose-response on dentin similar to the anticipated clinical efficacy. Highly demineralized specimens seem to be recommendable for measuring anti-caries effects on dentin in situ. Furthermore both fluoride-free dentifrices, one containing nanohydroxyapatite, did not hamper demineralization. The study was registered in the German Clinical Trials Register (DRKS-ID: DRKS00011653).

Evaluation of the value of re-wetting prior to resin infiltration of post-orthodontic caries lesions.

OBJECTIVES: Assessment of the influence of colour changes during the re-wetting process as a possible predictor for the final result after resin infiltration to mask post-orthodontic white spot lesions. MATERIALS AND METHODS: Resin infiltration (ICON; DMG, Hamburg, Germany) was performed according to the manufacturer's recommendation with the exception of repeated, at maximum three etching procedures based on the subjective decision of the dentist during a so called re-wetting process using ethanol. The masking effect by ethanol as well as after resin infiltration was evaluated by digital images taken before, for nine seconds during re-wetting and one week after treatment using CIE L*a*b* colour space. RESULTS: Twenty-nine patients (16 female) with a total of 221 lesions (ICDAS 2) were included (mean age 16 years). Mean time after debonding the orthodontic appliances was ten weeks. Colour changes during re-wetting, evaluated in the first ten patients (71 lesions) showed a significant correlation between the minimum ΔE observed during re-wetting and the final ΔE after resin infiltration (r = 0.65, p < 0.001; Spearman correlation). The main drop in ΔE becomes visible after three seconds when performing the re-wetting process. Regarding the 221 lesions, resin infiltration significantly reduced the colour difference between sound and lesion areas from a baseline ΔE (25th/75th percentiles) of 10.9 (8.2/13.2) to a ΔE of 4 (2.1/5.8) after one week (p < 0.001). The number of etching procedures correlated significantly with baseline ΔE (p < 0.05). CONCLUSIONS: The minimum ΔE observed during the re-wetting process seems to be a useful predictor for the final result of resin infiltration of post-orthodontic caries lesions. More prominent lesions with higher ΔE at baseline seem to require more erosion of the surface layer. In general, a significant and considerable clinical reduction of ΔE could be observed. CLINICAL SIGNIFICANCE: We corroborate that resin infiltration technique is a very useful method to mask caries lesions having developed during treatment with fixed orthodontic appliances. Colour changes while re-wetting the lesions with ethanol seem to be a valuable indicator for the number of required etching procedures.

Success and survival of post-restorations: six-year results of a prospective observational practice-based clinical study.

AIM: This prospective, noninterventional, multi-centre, practice-based study aimed to evaluate the longevity of endodontically treated teeth (ETT) restored with posts and to analyse factors influencing the success and survival of endodontic posts. METHODOLOGY: Eight general dental practitioners each placed up to 27 endodontic posts without any restriction to size and material. Teeth were restricted to incisors, canines and premolars. Multi-level Cox proportional hazards models were used to evaluate the association between clinical factors and time until failure. RESULTS: A total of 195 endodontic posts were followed-up for up to 6.5 years in 195 patients. Of these, 140 posts were judged as successful [mean success time: 59 (55-63) months]; the mean annual failure rate was 8.6%. This decreased to 4.4% when excluding recementations. 152 posts survived [mean survival time: 64 (60-67) months]. Recemented restorations had an eight times higher failure rate compared with new restorations. Furthermore, restorations with glass fibre post had a significantly lower success rate compared with titanium posts. CONCLUSION: Relatively low success and survival rates occurred for restorations with posts after root canal treatment in a private practice setting after a follow-up of up to 6.5 years. Recemented crowns had a high risk of failure.

Longevity of composite build-ups without posts-10-year results of a practice-based study.

AIM: The aim of this prospective, non-interventional, multi-center, practice-based study was, firstly, to evaluate the longevity of composite build-ups in endodontically treated teeth (ETT) without post placement and, secondly, to analyze factors influencing the success of these composite build-ups. METHODOLOGY: Each of seven general dental practitioners placed up to 50 composite build-ups without additional posts in ETT. Teeth were restricted to incisors, canines, and premolars. Several clinical data were recorded for 192 coronal restorations on ETT in 192 patients. Cox proportional hazard models were applied to analyze associations between clinical factors and time until failure. RESULTS: Within a follow-up period of 10 years, 167 restorations were judged as successful [mean success time, 110 (105-115) months] and 180 teeth survived [mean survival time, 114 (110-119) months]. The main failure type was fracture of the restoration (n = 15). The annual failure rate was 2.4%. In bivariate Cox regression, both factors such as number of restored tooth surfaces and adhesive were significantly associated with the failure rate. In multivariate Cox proportional hazards regression, none of the investigated factors were significantly associated with the failure rate. CONCLUSION: For composite build-ups in ETT without post placement, high success rates could be found after up to 10 years of observation time. Within the limitations of the present study, none of the analyzed factors such as "tooth type" or "number of restored tooth surfaces" was a significant predictor for the failure rate. CLINICAL RELEVANCE: Endodontically treated teeth can be successfully directly restored with composite build-ups even when no additional post is inserted. TRIAL REGISTRATION: The study was registered in the German Clinical Trials Register (DRKS-ID: DRKS00012882).

Risk factors for failure of class V restorations of carious cervical lesions in general dental practices.

OBJECTIVES: The aim of this retrospective, non-interventional, multi-center, practice-based study was to analyze factors influencing the survival of restorative treatments of one- and two-surface active cervical (root) caries lesions (CCLs). METHODS: Records from patients who visited five private practices regularly were searched for the presence of active one- and two-surface CCLs. Data from 1167 patients with 2070 CCLs being detected at least 6 months before the last recall visit were recorded. Kaplan-Meier-analyses were used to analyze time-to-failure. Cox proportional hazards models were used to evaluate the association between clinical factors and time until failure. RESULTS: Within 120 months [mean (SD) follow-up period:50 (40) months] 219 failures could be observed. Median survival time was 120 months. The AFR was 1.82% for one-surface restorations (CCL1) and 3.25% for two-surface restorations (CCL2). In multivariate Cox regression two-surface cervical restorations showed 1.75 times higher failure rates than one-surface cervical restoration. Furthermore, CCL being checked up more than twice a year showed significantly higher failure rates than restorations being checked up less than twice a year (p < 0.001). CONCLUSION: Low failure rates could be found for restorative treatment strategies of one- as well as for two-surface CCLs. CLINICAL SIGNIFICANCE: Restorative treatment of CCLs is a viable way to manage one-surface CCLs. However, the proximal extension of the CCL significantly shortens the longevity of the restoration. The study was registered in the German Clinical Trials Register (DRKS-ID: DRKS00012510).

Influence of highly concentrated fluoride dentifrices on remineralization characteristics of enamel in vitro.

OBJECTIVES: The aim of this in vitro study was to evaluate the role of highly fluoridated dentifrice on remineralization characteristics of lowly and highly pre-demineralized enamel artificial caries lesions. METHODS: Bovine enamel specimens were prepared (pH 4.95; 21 days) and discriminated in either lowly [L] or highly [H] pre-demineralized artificial caries lesions. Specimens with a mean ΔZbaseline,L (95% CI) of 5120 (4995; 5245) vol.% × µm and a mean ΔZbaseline,H of 8187 (8036; 8339) vol.% × µm were selected and randomly allocated to 12 groups (n = 20). Treatments during pH-cycling (28 days; 6 × 60 min demineralization/day) were brushing 2×/day with fluoride-free (0 ppm F- [L0/H0]), 1100 ppm F- [L1100/H1100], 2800 ppm F- [L2800/H2800], 5000 ppm F- [L5000/H5000], 5000 ppm F- + glycerin [L5000 + glycerin/H5000 + glycerin], and 5000 ppm F- + TCP [L5000 + TCP/H5000 + TCP] containing dentifrices. Dentifrice slurries were prepared with deionized water (1:3wt/wt). After cycling specimens presenting lesion surface loss were discarded and for the remaining 202 specimens, transversal microradiographic (TMR) analyses (ΔZpH-cycle/LDpH-cycle) were performed again. Changes in mineral loss (ΔΔZ = ΔZbaseline - ΔZpH-cycle) and lesion depth (ΔLD = LDbaseline - LDpH-cycle) were calculated. RESULTS: Significant differences for ΔΔZ could be found between L0, L1100, and L5000 as well as H0, H1100, and H2800/H5000 (p ≤ 0.01; ANCOVA). Except for 0 ppm F-, higher ΔΔZ could be found in highly compared with lowly demineralized specimens (p ≤ 0.004; ANCOVA). After pH-cycling, a second lesion front could only be observed in H5000 and H5000 + TCP. The correlation between ΔΔZ and F- was moderate for lowly and highly demineralized lesions (rL = 0.591; pL < 0.001; rH = 0.746; pH < 0.001), indicating a fluoride dose response for both. CONCLUSION: For both baseline substrate conditions, a dose response for fluoride could be revealed. CLINICAL SIGNIFICANCE: Remineralization characteristics of enamel directly depended on baseline mineral loss.