Influence of TiO2 nanoparticles on the optical properties of resin composites

ObjectivesTo determine the influence of titanium dioxide (TiO₂) nanoparticle addition on the opalescence, color, translucency and fluorescence of experimental resin composites.MethodsA light curing resin matrix was made by mixing 60 wt.% Bis-GMA and 40 wt.% TEGDMA. Silane coated glass filler (mean particle size: 1.55 μm) was added in the ratio of 50 wt.% of the resin composites. A fluorescent whitening agent was also added (0.05 wt.%). TiO₂ nanoparticles (<40 nm) were added with the concentrations of 0, 0.1, 0.25 and 0.5 wt.%. Reflected and transmitted colors of 1 and 2 mm thick specimens were measured relative to the illuminant D65 with reflection spectrophotometers. Opalescence parameter (OP), color difference (ΔE*_ab), translucency parameter (TP), fluorescence parameter (FL), and fluorescence and opalescence spectra were calculated.ResultsFor the 1 mm thick specimens measured with 3 mm × 8 mm rectangular aperture, when the concentration of TiO₂ increased from 0% to 0.5%, OP increased from 2.4 to 18.0, TP decreased from 35.4 to 13.1, and fluorescence spectra remained unchanged. Color difference between these specimens was in the range of 3.4–6.6 ΔE*_ab units. OP values were significantly influenced by the thickness of the specimens and the configuration of the spectrophotometers (p < 0.05).SignificanceAddition of TiO₂ nanoparticles significantly increased the opalescence of resin composites while leaving the fluorescence spectra unchanged; however, it significantly decreased the translucency and also changed the color (p < 0.05). Resin composites with 0.1–0.25% TiO₂ nanoparticle would simulate the opalescence of human enamel.     

Effects of duration of whitening strip treatment on tooth color: A randomized,placebo-controlled clinical trial

ObjectivesA randomized, double-blind, placebo-controlled clinical trial was conducted to evaluate efficacy and safety of 6% hydrogen peroxide whitening strip used twice daily over an extended, 6-week period.MethodsAfter informed consent, 40 eligible adults were randomly assigned to 6% hydrogen peroxide whitening strips (Crest Whitestrips, The Procter & Gamble Company, USA) or placebo strips without peroxide. Treatment was twice daily for 30 min, and response was evaluated biweekly after initial (Week 2) and extended (Weeks 4 and 6) use. Tooth color was measured under standardized lighting conditions using digital image analysis, and safety was assessed from clinical examination and interview. Whitening was measured using data derived from digital images taken at baseline compared to post-treatment, with outcomes reported using the CIELAB color notation system. Analysis of variance and covariance were used to assess initial response, and repeated measures regression analysis was used to model color change during sustained use.ResultsForty subjects (25–58 years old) started the study. At baseline, L* ranged from 68.0 to 76.8, a* ranged from 8.0 to 11.8, and b* ranged from 16.4 to 23.1. Groups differed significantly (p < 0.001) on all color parameters at Week 2 and thereafter, favoring the 6% hydrogen peroxide strips. Week 2 adjusted means ± SE were ?2.1 ± 0.2 for Δb* and 1.9 ± 0.2 for ΔL* for the peroxide group compared to ?0.3 ± 0.2 for Δb* and 0.4 ± 0.2 for the placebo group. With sustained use (Weeks 2–6), the slope for the peroxide strip was estimated as ?0.3 for Δb* and +0.2 for ΔL* per week, with both slopes differing significantly from zero (p < 0.0001), while slopes for the placebo strip were not significant (p = 0.22) and nearly zero. Treatment was generally well tolerated, with adverse events confined to symptoms only.ConclusionsTwice-daily use of 6% hydrogen peroxide whitening strips resulted in teeth becoming lighter and less yellow versus baseline and placebo during initial 2-week use, with no evidence of placebo response during sustained (Weeks 2–6) use.     

Color and contrast ratio of resin composites for whitened teeth

ObjectivesThe purpose of this study was to determine the optical properties, color and contrast ratio (CR) of commercially available resin composites marketed for the restoration of whitened teeth.MethodsTwenty-six resin composites designed for restoration of whitened teeth and four shade B1 (control) were evaluated. Five resin composite disks (d = 12 mm, h = 1.54 mm) were fabricated for each shade of composite and were stored in water at 37 °C for at least 24 h. A colorimeter was used to measure specimen color over both white and black backgrounds. CIELAB and CIExyY color spaces were used. The CIELAB color notation system provides values for L*a*b*. The CIExyY system provides lightness and chromaticity values, where Y represents lightness and xy chromaticity. The contrast ratio (CR) was assessed using, CIE xyY, of the specimens against black (Yb) and white (Yw) backgrounds, with CR = Yb/Yw. The data for L*, a*, b* and CR were analyzed by one-way ANOVA, Tukey's test, and the correlation L* and CR was analyzed by Pearson correlation test (α = 0.05).ResultsSignificantly different L*, a*, b* values and CR were observed. Premise XL2 had the highest L* and CR values and Vit-l-escence PS had the lowest. Vit-l-escence PS had the highest a* value and Point 4XL2 had the lowest, Premise XL1 had the highest b* value and Supreme WB the lowest. The L* and CR correlation was positive and statistically significant.ConclusionsComposites designated for whitened teeth have different levels of color and contrast ratio. Awareness of the optical properties of the composites allows the operator to choose the appropriate materials to mimic the remaining tooth structure.     

Frequency of periodontal pathogens in equivalent peri-implant and periodontal clinical statuses

ObjectivesThis study tested the hypotheses that there is: (1) higher bacterial frequency in peri-implantitis/periodontitis, followed by mucositis/gingivitis and peri-implant/periodontal health; (2) similar bacterial frequency between comparable peri-implant and periodontal clinical statuses.Design of studyThe presence of Porphyromonas gingivalis, Tannerella forsythia, Campylobacter rectus, Prevotella intermedia, Treponema denticola and Aggregatibacter actinomycetemcomitans was evaluated in peri-implant (n = 53) and periodontal (n = 53) health; mucositis (n = 50), gingivitis (n = 50), peri-implantitis (n = 50) and periodontitis (n = 50).ResultsThe pattern of peri-implant bacterial frequency was not as expected (peri-implantitis > mucositis > health). Except for P. intermedia (p > 0.05), bacterial frequency was higher in peri-implantitis than health (p < 0.05). The frequency of P.gingivalis and red complex species were higher in peri-implantitis than mucositis (p < 0.05). In periodontal samples, T. forsythia and T. denticola showed the expected pattern of frequency (periodontitis > gingivitis > health). The frequencies of C. rectus and T. forsythia were higher in healthy teeth/gingivitis than healthy implants/mucositis, respectively (p < 0.05). The frequency of P. gingivalis and A. actinomycetemcomitans were similar between periodontitis and peri-implantitis (p > 0.05) while all other species occurrences were higher in periodontitis than peri-implantitis (p < 0.05).ConclusionsBacterial frequency increased from peri-implant/periodontal health to peri-implantitis/periodontitis but not from mucositis/gingivitis to peri-implantitis/periodontitis. There was a trend towards higher bacterial frequency in teeth than implants.     

Hydrogen peroxide induces cell proliferation and apoptosis in pulp of rats after dental bleaching in vivo: Effects of the dental bleaching in pulp

ObjectiveThis study provides an in vivo evaluation of the inflammatory response, levels of cell proliferation and apoptosis, and the presence of necrosis after dental bleaching with two concentrations of hydrogen peroxide (H₂O₂).DesignWistar rats were divided into Control (placebo gel), BLUE (20% H₂O₂, 1 × 50 min), and MAXX (35% H₂O₂, 3 × 15 min) groups. At 2 and 30 days, the rats were killed (n = 10). The jaws were processed for histology analysis and PCNA and Caspase-3-cleaved immunohistochemistry, and data were submitted to the Mann-Whitney or ANOVA test (P < 0.05).ResultsAt 2 days, the MAXX group showed necrosis and the BLUE group revealed moderate inflammation on the occlusal third of the crown (P < 0.05). At 30 days, tertiary dentin had formed and there was an absence of inflammation. The level of cell proliferation was higher in the middle third of the BLUE group (P < 0.05), and cervical of MAXX at 2 days (P < 0.05), decreasing at 30 days. The apoptosis was present at 2 days, particularly in the cervical third of the crown in the bleached groups (P < 0.05), with a decrease only at 30 days in the BLUE group (P < 0.05).ConclusionsThe concentration of H₂O₂ influences effects on the pulp tissue, where a higher concentration of H₂O₂ can cause necrosis in the pulp and a prolonged effect within the apoptotic process; lower concentrations of H₂O₂ provide moderate inflammation, cell proliferation and apoptosis with a reduction of these processes over time.     

Stability of miniscrews with different continuous orthodontic forces as measured by cone-beam computed tomography

PurposeMiniscrew stability is a key for successful orthodontic anchorage reinforcement. Light force as 50 g has been proposed to efficiently retract canine; however, for miniscrew stability, its efficiency is still questionable. This study aimed to evaluate and compare miniscrew displacements loaded with 50 and 150 g to retract upper canines.Subjects and methodsTwenty four miniscrews (1.4 mm diameter and 7 mm length) were placed in twelve orthodontic patients (female, 22.55 ± 4.8 years old) who required miniscrews for maximum anchorage. Cone-beam computed tomography (CBCT) was taken to assess the miniscrew displacement in three dimensions. The X, Y, Z coordination points at the miniscrew head and tail with anterior nasal spine as a reference point were recorded and analyzed the displacements during 3 months using one-sample t-test and pair t-test.ResultsMiniscrews were significantly displaced after loading 50 and 150 g at 2 and 3 months compared to baseline (P < 0.001). At 2 months, the displacement of the miniscrews at head and tail had no statistical significance between 50 and 150 g (P > 0.05). However, at 3 months, there were statistically significant displacements between 50 and 150 g. This displacement was found to be greater in 150 g and at head more than at tail (P < 0.05).ConclusionThis study concluded that miniscrews could be significantly displaced with 50 and 150 g during 3 months wherein the heavier loading force essentially caused more miniscrew mobility. Clinically, it is suggested to use proper magnitude of force to miniscrews with care in order to overcome orthodontic anchorage failure.     

Self-cured resin modified by quaternary ammonium methacrylates and chlorhexidine: Cytotoxicity,antimicrobial, physical,and mechanical properties

ObjectiveTo evaluate the addition of dimethylaminohexadecyl methacrylate (DMAHDM) and chlorhexidine diacetate on cytotoxicity, antimicrobial activity, physical, and mechanical properties of a self-cured resin.Methods132 disk-shaped and 48 rectangular specimens were divided into four experimental groups as described: Control Group (CG – no addition), dCHX (1%), DMAHDM (5%), and DMAHDM + dCHX (5% + 1%). The biofilm viability, flexural strength (FS - ISO 20795-1:2013), surface roughness (SR), and color stability (ΔE) were analyzed after being stored for 4 weeks in distilled water and immersed for 72 h in coffee. Cytotoxicity was measured after 24 h, 3, and 7 days of elution using an MTT test on L929 cells (ISO 10993-5:2009). SR and ΔE were measured by a contact profilometer and a spectrophotometer using the CIELab parameter. Data were submitted to ANOVA and Bonferroni’s/Tukey’s tests (p ≤ 0.05).ResultsSignificant antimicrobial activity against Streptococcus mutans and Candida albicans was detected in all groups when compared to the CG (p < 0.05). Only the dCHX group, in 24 h of elution, demonstrated no cytotoxicity effects. There was a statistical difference for FS on the tested groups (p < 0.05). No differences were detected in the initial roughness’ measurements among the groups (p > 0.05). However, after storage and immersion in coffee, the groups containing DMAHDM presented with rougher surfaces and significantly lower color stability compared to the control (p < 0.05).SignificanceThe addition of dCHX and DMAHDM in self-cured resin presented antimicrobial properties; however, cytotoxicity, physical, and mechanical properties were compromised.     

Effects of connective tissue growth factor on human periodontal ligament fibroblasts

ObjectiveThe aim of this study was to evaluate the effects of different concentrations of connective tissue growth factor (CTGF) on human periodontal ligament fibroblasts(HPLFs).DesignHPLFs were cultured and identified. Then, different concentrations of CTGF (1, 5, 10, 50, 100 ng/ml) were added to the HPLF culture. Next, CCK-8 assays, alkaline phosphatase (ALP) assays, hydroxyproline determination, alizarin red staining methods, Transwell chambers and real-time PCR methods were applied to observe the effects of CTGF on the proliferation, ALP activity, synthesis of collagen, formation of mineralized nodules and migration. We also studied expression of ALP, fiber link protein (FN), integrin-binding sialoprotein (IBSP), osteocalcin (OC), and integrin beta 1 (ITGB1) mRNA by HPLFs. Statistical significance was assumed if P < 0.05 or P < 0.01.ResultsThe addition of CTGF (1, 5, 10 ng/ml) remarkably promoted the proliferation and collagen synthesis of HPLFs compared with controls. CTGF (1, 5, 10, 50 ng/ml) improved ALP activity of HPLFs, and at all concentrations, CTGF (1, 5, 10, 50, 100 ng/ml) improved the expression of ALP, FN, IBSP and ITGB1 mRNA. In addition, CTGF (1, 5, 10, 50, 100 ng/ml) promoted the migration of HPLFs, which was dose-dependent, with maximal promotion in the 10 ng/ml group (P < 0.05 or P < 0.01).ConclusionsThus, in a certain range of concentrations, CTGF can promote the biological effects, including proliferation, migration and collagen synthesis of HPLFs, to promote the differentiation of HPLFs in the process of osteogenesis.     

Modification of metallic materials for a white appearance without coating and plating

PurposeThe purpose of this study was to develop white-colored metals for metal injection moldings, and white-colored surface preparation for metals to satisfy the esthetic demands of patients.Materials and methodsTwo methods for white coloration of metals were developed for two kinds of metals. For white-colored silver metal, silver powder was baked at 700 °C for 15 min with or without the alumina plate. For white-colored surface preparation, titanium wire, orthodontic brackets and dental implants were baked at 1000 °C for 15 min. Two kinds of white-colored specimens were used for evaluation of coloration, mechanical strength and the components.ResultsTreated silver metal was visually white, and closed to the color of white porcelain panel evaluated by a colorimeter. From the results of load-deflection tests, the mechanical strength of white-colored silver metal was almost same as that of non-treated one. Surface prepared titanium objects were also visually white, and closed to the color of white porcelain, and thickness of white color layer was 10–50 μm. Load-deflection tests revealed that white-colored titanium metal was fragile compared to non-treated one. The component of white-colored silver metal was approximately 100% Ag. On the other side, the surface component of white-colored titanium metal was titanium dioxide.ConclusionTwo methods of white coloration for metals were developed. One method is use of injection molding especially for prevention of crushing of ceramics when combined with them. The other is a white-colored surface preparation for dental appliances, including orthodontic appliances.     

Association of the XPD and XRCC3 gene polymorphisms with oral squamous cell carcinoma in a Northeastern Brazilian population: A pilot study

Objectiveto evaluate the association between XPD and XRCC3 polymorphisms and oral squamous cell carcinoma (OSCC).Designthe sample consisted of 54 cases of OSCC and 40 cases of inflammatory fibrous hyperplasia (IFH). Genotypes were determined by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method.ResultsXPD-Lys/Gln was more common in IFH (n = 28; 70%) than in OSCC (n = 24; 44.4%) (OR: 0.3; p < 0.05). XPD-Gln was more frequent in high-grade lesions (0.48) than in low-grade lesions (0.21) (OR: 3.4; p < 0.05). The Gln/Gln genotype was associated with III and IV clinical stages (OR: 0.07; p < 0.05). XRCC3-Met was more frequent in OSCC (0.49) than in IFH (0.35) (OR: 2.6; p < 0.05). The Met/Met genotype was associated with the presence of metastases (OR: 8.1; p < 0.05) and with III and IV clinical stages (OR: 0.07; p < 0.05).Conclusionsin this sample, the frequency of XPD-Gln in IFH suggests that this variant may protect against OSCC. The presence of the XRCC3-Met allele seems to contribute to the development of OSCC, metastases and more advanced stages in these lesions.     

Curing potential and color stability of different resin-based luting materials

PurposeTo determine the curing potential and color stability of resin-based luting materials for aesthetic restorations.Material and MethodsFour resin-based luting agents were tested: traditional dual-activated resin cement (RelyX ARC, ARC), amine-free dual-activated resin cement (RelyX Ultimate, ULT), light-activated resin cement (RelyX Veneer, VEN), and pre-heated restorative resin composite (Filtek Supreme, PHC). Degree of C = C conversion was determined by infrared spectroscopy (n = 3) with direct light exposure or with interposition of 1.5-mm-thick ceramic (e.max Press HT) between the luting material and light. The curing potential considered the ratio between these two scenarios. Color difference (n = 6) was determined by CIELAB (ΔE_ab) and CIEDE2000 (ΔE₀₀) methods, by spectrophotometer measurements made 24 h after photoactivation and 90 days after storage in water. Data was submitted to ANOVA and Tukey’s test (α = 0.05).ResultsThe luting agents affected both conversion and color stability. With ceramic, ARC produced the highest conversion among the tested groups (75 ± 1%) and the pre-heated composite (PHC) the lowest one (51 ± 3%), but the curing potential was similar for all materials. ULT produced lower ΔE_ab than ARC. PHC presented the lowest color difference when considered both CIELAB and CIE2000 methods (ΔE_ab 2.1 ± 0.4; ΔE₀₀ 1.6 ± 0.2).SignificanceAll luting strategies presented high curing potential. Amine-free dual-activated material was able to reduce color difference than that formulated with the amine component. Pre-heated composite produced the least color variation after storage.     

Color change of some aesthetic dental materials: Effect of immersion solutions and finishing of their surfaces

ObjectivesThe purpose of this research was to evaluate the color change of five aesthetic dental materials, before and after immersion in distilled water and blue food color solution for 7 and 21 days, and to study the effect of finishing the surfaces on any color change.MethodsDisc shaped samples of five types of light curing composite (A2) (n = 10 samples/composite) were prepared and all samples were light-cured with a Plasma Arc light cure unit for ten seconds. One side of each sample disc was finished and polished with a Super-Snap system all samples. After 24 h, color measurements of each sample were conducted using a digital spectrophotometer. Five sample discs from each composite group were immersed in 30 ml of food color solution for 7 and 21 days, while the remaining five sample discs were immersed in 30 ml of distilled water as a control. Color measurements were repeated for all samples at 7 and 21 days after immersion. The color changes were statistically analyzed using t-tests within the same group. A result was considered statistically significant at α = 0.05.ResultsThe color differences (ΔE) ranged from 0.4 to 4.66 and statistically significant differences on the finished and unfinished surfaces were observed after immersion in the food color solution for 7 days. No significant differences were found in any group after immersion in the food color solution for 21 days. The Tetric EvoCeram and Arabesk groups showed less color differences after 7 and 21 days than other composites.ConclusionFinished composite surfaces showed less coloration than unfinished surfaces after 7 days, but all surfaces (finished and unfinished) were highly colored for all composite types after 21 days.     

Concentration additivity of coefficients for maxillofacial elastomer pigmented to skin colors

ObjectiveThe purpose of this study is to determine a regression model which performs accurately for predicting Kubelka–Munk (K–M) absorption (K) and scattering (S) coefficients of pigment mixtures in maxillofacial elastomer (MFE).MethodsSpecimens at varying thicknesses of 19 shades of skin-colored MFE were made incorporating tan, red, yellow and black pigments. Using a non-contact 45°/0° spectral reflectance system, reflectance values were obtained and fit by non-linear regression to corrected K–M theory to determine observed K and S values. Predicted values were calculated using: first order linear regression model (M₁), second order square-factor model (M_2S), second order interaction-factor model (M_2I) and complete second order model (M_2C). Errors between observed and predicted values for each model at each wavelength studied are evaluated. Differences in color and the Translucency Parameter (TP) at a thickness of 1.5 mm based on CIE2000 color difference formula between observed and predicted values were also analyzed using repeated-measures ANOVA (α = 0.05).ResultsM_2C shows less absolute differences in color and TP (1.5 mm) than those for the M₁ and M_2S models (P < 0.05).SignificanceWithin limitations of this study, the complete second order regression model performs accurately in concentration additivity of pigmented maxillofacial elastomer mixture. This regression model is recommended as a viable alternative in the application of colorant formulation based on corrected K–M model for improving appearance match of pigmented maxillofacial prosthesis to human skin.     

Effect of fluoride toothpaste with nano-sized trimetaphosphate on enamel demineralization: An in vitro study

ObjectiveThis study evaluated the effect of toothpastes containing 1100 ppm F associated or not with micrometric or nano-sized sodium trimetaphosphate (TMP) on enamel demineralization in vitro, using a pH cycling model.DesignBovine enamel blocks (4 mm × 4 mm, n = 96) were randomly allocated into eight groups (n = 12), according to the test toothpastes: Placebo (without fluoride or TMP); 1100 ppm F (1100F); 1100F plus micrometric TMP at concentrations of 1%, 3% or 6%; and 1100F plus nanosized TMP at 1%, 3% or 6%. Blocks were treated 2×/day with slurries of toothpastes and submitted to a pH cycling regimen for five days. Next, final surface hardness (SHf), integrated hardness loss (IHL), differential profile of integrated hardness loss (ΔIHL) and enamel fluoride (F) concentrations were determined. Data were analyzed by ANOVA and Student-Newman-Keuls’ test (p < 0.05).ResultsThe use of 1100F/3%TMPnano led to SHf 30% higher (p < 0.001) and IHL ∼ 80% lower (p < 0.001) when compared to 1100F. This toothpaste also resulted in ∼64% reduction of mineral loss (ΔIHL) when compared to 1100F. Moreover, the addition of nano-sized TMP promoted increases in enamel F uptake of 90%, 160% and 100%, respectively for the concentrations of 1%, 3% and 6%, when compared to 1100F (p < 0.001).ConclusionThe addition of nano-sized TMP at 3% to a conventional toothpaste significantly decreased enamel demineralization when compared to its counterparts without TMP or supplemented with micrometric TMP.     

Comparison of craniofacial morphology,head posture and hyoid bone position with different breathing patterns

ObjectivesThe aim of this study was to evaluate differences in craniofacial morphology, head posture and hyoid bone position between mouth breathing (MB) and nasal breathing (NB) patients.MethodsMouth breathing patients comprised 34 skeletal Class I subjects with a mean age of 12.8 ± 1.5 years (range: 12.0–15.2 years). Thirty-two subjects with skeletal Class I relationship were included in the NB group (mean 13.5 ± 1.3 years; range: 12.2–14.8 years). Twenty-seven measurements (15 angular and 12 linear) were used for the craniofacial analysis. Additionally, 12 measurements were evaluated for head posture (eight measurements) and hyoid bone position (four measurements). Student’s t-test was used for the statistical analysis. Probability values <0.05 were accepted as significant.ResultsStatistical comparisons showed that sagittal measurements including SNA (p < 0.01), ANB (p < 0.01), A to N perp (p < 0.05), convexity (p < 0.05), IMPA (p < 0.05) and overbite (p < 0.05) measurements were found to be lower in MB patients compared to NB. Vertical measurements including SN-MP (p < 0.01) and PP-GoGn (p < 0.01), S-N (p <0.05) and anterior facial height (p < 0.05) were significantly higher in MB patients, while the odontoid proses and palatal plane angle (OPT-PP) was greater and true vertical line and palatal plane angle (Vert-PP) was smaller in MB patients compared to NB group (p < 0.05 for both). No statistically significant differences were found regarding the hyoid bone position between both groups.ConclusionsThe maxilla was more retrognathic in MB patients. Additionally, the palatal plane had a posterior rotation in MB patients. However, no significant differences were found in the hyoid bone position between MB and NB patients.     

Nanohybrid vs. fine hybrid composite in Class II cavities: Clinical results and margin analysis after four years

ObjectivesThis controlled prospective split-mouth study evaluated the clinical behavior of two different resin composites in extended Class II cavities over a period of four years.MethodsThirty patients received 68 direct resin composite restorations (Grandio bonded with Solobond M: n = 36, Tetric Ceram bonded with Syntac: n = 32) by one dentist in a private practice. All restorations were replacement fillings, 24 cavities (35%) revealed no enamel at the bottom of the proximal box, in 33 cavities (48%) the proximal enamel width was less than 0.5 mm. The restorations were examined according to modified USPHS criteria at baseline, and after six months, one, two, and four years. At each recall, impressions were taken for replica preparation. Replicas of 44 select subjects were assessed for marginal quality under a stereo light microscope (SLM) at 130× and 22 replicas were assessed under a scanning electron microscope (SEM) at 200×.ResultsBoth recall rate and survival rate were 100% after four years of clinical service. No significant difference was found between the restorative materials (p > 0.05; Mann–Whitney U-test). Hypersensitivities were significantly reduced over time (p < 0.05; Friedman test). A significant deterioration over time was found for the criteria marginal integrity (66% bravo after four years), tooth integrity (15% bravo), filling integrity (73% bravo) and proximal contact (p < 0.05; Friedman test). SLM and SEM analysis of restoration margins revealed differences in the amount of perfect margins, in favor of Tetric Ceram (p < 0.05).SignificancesBoth materials performed satisfactorily over the four-year observation period. Due to the extension of the restorations, wear was clearly visible after four years of clinical service with 50% bravo ratings.     

Operator vs. material influence on clinical outcome of bonded ceramic inlays

ObjectiveThe aim of the present study was to clinically evaluate the suitability of Definite Multibond and Definite ormocer resin composite for luting of Cergogold glass ceramic inlays in a two-center trial involving two dentists.MethodsThirty-nine patients received 98 Cergogold inlays with at least one inlay luted with Definite Multibond/Definite (n = 45) and at least one inlay luted with Syntac/Variolink Ultra (n = 53) in a split mouth design. Treatments were carried out in two private practices by two operators (Operator A: n = 38; Operator B: n = 60). Forty-four cavities required caries profunda treatment, 23 cavities exhibited no enamel at the cervical margin. At baseline (2 months), and after 6, 14, 27, and 51 months of clinical service, the restorations were investigated according to modified USPHS criteria.ResultsThe drop-out rate was 3% after 4 years. After 48 months of clinical service, 21 restorations in 16 patients (9 luted with Definite, 12 with Variolink; 2 placed by operator A and 19 by operator B) had to be replaced due to inlay fracture (n = 11), tooth fracture (n = 4), hypersensitivities (n = 3), or marginal gap formation (n = 3). Seventy-seven inlays were in good condition (survival rate 89.9%, median survival time 4.2 years (95% confidence interval ±0.25; survival analysis by Kaplan–Meier algorithm). Survival rate after 4 years was 97.4% for operator A, and 75.4% for operator B (p = 0.002; Log Rank/Mantel-Cox) resulting in annual failure rates of 0.6% and 6.2%, respectively. The operators did not differently judge the clinical behaviour of the luting procedures (Mann–Whitney U-test, p > 0.05). Independent of the operator and the used luting system, the following criteria significantly changed over time: color match, marginal integrity, tooth integrity, inlay integrity, sensitivity, hypersensitivity, and X-ray control (p < 0.05; Friedman test). Significant differences between operators over the whole period were computed for the criteria marginal integrity, tooth integrity, and inlay integrity (p < 0.05, Mann–Whitney test). Differences between luting materials were only present during single recalls.SignificancesFor luting of ceramic inlays, only slight differences between the two luting systems were detectable. The operator influence on clinical outcome was clearly proven.     

Immunoexpression of BMP-2 and BMP-4 and their receptors,BMPR-IA and BMPR-II,in ameloblastomas and adenomatoid odontogenic tumors

ObjectivesThe present study evaluated the immunohistochemical expression of BMP-2 and BMP-4 and of their receptors (BMPR-IA and BMPR-II) in solid ameloblastoma (SA), unicystic ameloblastoma (UA) and adenomatoid odontogenic tumor (AOT) in order to obtain a better understanding of their role in the development and biological behavior of these tumors.DesignThis study analyzed these proteins in 30 cases of SA, 10 cases of UA, and 30 cases of AOT. Immunoexpression was evaluated in the parenchyma and stroma by attributing the following scores: 0, no stained cells; 1, ≤10%; 2, >10% and ≤25%; 3, >25% and ≤50%; 4, >50% and ≤75%.; 5, >75% stained cells.ResultsIn SAs, positive correlations were observed between the stromal and parenchymal expression of BMP-2 (p < 0.001) and between the stromal expression of BMP-2 and BMP-4 (p = 0.020), as well as between the stromal expression of BMPR-II and BMP-4 (p = 0.001) and the stromal and parenchymal expression of BMPR-II (p < 0.001). In UAs, correlations were detected between the stromal and parenchymal expression of BMP-4 (p = 0.035) and between the stromal expression of BMP-4 and BMPR-IA (p = 0.022). In AOTs, analysis of immunoexpression in the parenchyma revealed positive correlations between all proteins.ConclusionBMPs and their receptors play an important role in the differentiation and development of ameloblastomas and AOTs, but may not explain the different biological behaviors of these lesions. The positive correlation observed in AOTs might be related to the formation of mineralized material in this tumor.     

Effects of polyphosphates and fluoride on hydroxyapatite dissolution: A pH-stat investigation

ObjectivesThis study investigated the immediate and sustained effect of sodium trimetaphosphate (TMP) and sodium hexametaphosphate (HMP) associated or not with fluoride (F) on hydroxyapatite (HA) dissolution using an erosion-like model, considering as well as the influence of salivary coating.DesignBaseline dissolution rates were determined for HA discs using a pH-stat system. In the first set of experiments, HA discs were treated with 1100 μg F/mL, 1% or 8% of HMP, 1% or 8% of TMP and 1100 μg F/mL associated with 1% or 8% of HMP or TMP, totaling 9 groups (n = 8). In a second phase, HA discs were kept in pooled human saliva at 37 °C for 2 h before treatment with deionised water and 1100 μg F/mL associated with 1% or 8% of HMP or TMP, totaling 5 groups (n = 8). The post-treatment dissolution rate was determined from three consecutive 30-min assays. Data were analysed using 2 and 3-way ANOVA followed by Fisher and Holm–Sidak methods, respectively (α = 0.05).ResultsAll test solutions promoted reduction in HA dissolution rate when compared to baseline control in the first post-treatment run (p < 0.001). However, a synergistic effect was only observed between fluoride and 1% HMP. Moreover, the duration of inhibitory effect was greater when 8% HMP and 1 or 8% HMP associated with F were assessed (p < 0.001). The presence of salivary coating led to higher protection for all groups when compared to discs without coating (p < 0.001).ConclusionThe reduction of HA dissolution rate, as well as the duration of this effect were influenced by fluoride, type and concentration of phosphate salt and the presence of a salivary coating.