Camouflage effects following resin infiltration of postorthodontic white-spot lesions in vivo: One-year follow-up

Objective:To assess camouflage effects by concealment of postorthodontic white-spot lesions (WSLs) to sound adjacent enamel (SAE) achieved over 12 months with resin infiltration (Icon, DMG, Hamburg, Germany).Methods: Twenty subjects (trial teeth n_teeth = 111) who had received resin infiltration treatment of noncavitated postorthodontic WSLs were contacted for a 1-year follow-up assessment of CIE-L*a*b* colors (T12). Color and lightness (CIE-L*a*b*) data for WSLs and SAE were compared to baseline data assessed before infiltration (T0) and those assessed after 6 months (T6), using a spectrophotometer. The target parameter was the difference between the summarized color and lightness values (ΔE_WSL/SAE). Intergroup (WSL, SAE) and intertime comparisons (T0 vs T6, T12) were performed using paired t-tests at a significance level of α = 5%.Results:Nine subjects (trial teeth n_teeth = 49; male/female ratio 5/4; age range 13–19 years) were available at T12. After the highly significant reduction of ΔE_WSL/SAE discrepancies between T0 and T6, analysis of 12-month records revealed color and lightness discrepancy of WSL vs SAE that was significantly decreased compared with baseline, indicating an assimilation of WSL color to SAE appearance after infiltration, while an additional reduction of discrepancies between T6 and T12 was not significant.Conclusion:As color and lightness characteristics of the Icon infiltrant as well as the esthetic camouflage effects achieved by WSL infiltration were not altered significantly or clinically relevant after 12 months, the method of resin infiltration can be recommended for an enduring esthetic improvement of postorthodontic WSL. (Angle Orthod. 2015;85:374–380.)     

Esthetic improvements of postorthodontic white-spot lesions treated with resin infiltration and microabrasion: A split-mouth,randomized clinical trial

Objective:To compare the esthetic improvement between postorthodontic white-spot lesions (WSLs) treated by resin infiltration and microabrasion for 12 months.Materials and Methods:A total of 20 patients with 128 teeth with postorthodontic WSLs were recruited. A simple randomized, split-mouth, positive controlled design was used to allocate patients to resin infiltration or microabrasion groups. The lesion area ratio (R value) was calculated between the area of a WSL and the labial surface of the corresponding tooth based on standardized clinical photographs. The color change (ΔE) of each tooth was measured with a Crystaleye spectrophotometer (Olympus, Tokyo, Japan). Every measurement was taken before treatment (T0) and at different time points after treatment: 1 week (T1), 6 months (T6), and 12 months (T12).Results:A total of 16 patients with 108 trial teeth were available at T12. Each group had 54 trial teeth. In both groups, there was a significant decrease in R value and ΔE between T1 and T0 (P < .0001). In the infiltration group, the R value and ΔE had no significant changes over time from T1 to T12. In the microabrasion group, the R value and ΔE decreased significantly from T1 to T6. The R value of resin infiltration was lower when compared with microabrasion at every recall point (P < .001). The ΔE had no significant differences between the two groups at any timepoint.Conclusions:Resin infiltration and microabrasion improved the esthetic appearance of WSLs and showed sufficient durability for 12 months. Resin infiltration showed a better esthetic improvement effect when compared with microabrasion at 12 months.     

Esthetic comparison of white-spot lesion treatment modalities using spectrometry and fluorescence

Objective:To compare the esthetic improvements of white-spot lesions (WSLs) treated by fluoride, casein phosphopeptide amorphous calcium phosphate (CPP-ACP), or resin infiltration.Materials and Methods:WSLs were created on human enamel and randomly assigned to four groups: NaF (500 ppm), CPP-ACP, resin infiltration (Icon), or distilled deionized water (DDW; control group). The color change (ΔE) of each specimen was measured with a Crystaleye spectrophotometer, and fluorescence loss (ΔQ) was measured by quantitative light-induced fluorescence (QLF), at different time points after treatment: baseline (0 weeks), 2 weeks, 4 weeks, and 6 weeks.Results:The ΔE and ΔQ baseline values for the four groups before the treatments did not differ significantly. Icon treatment improved the WSL color significantly and gave the lowest ΔE (2.9 ± 1.2 on average) compared with other treatments (P < .01). The Icon treatment also resulted in a significant change in the ΔQ of WSLs compared with baseline (P < .01). In the NaF and CPP-ACP treatment groups, ΔQ showed significant recovery compared with the baseline values only after 4 weeks after treatment (P < .05).Conclusions:Resin infiltration is more effective than NaF or CPP-ACP in providing esthetic improvement of WSLs.     

Do total or partial etching procedures effect the rate of white spot lesion formation? A single-center,randomized, controlled clinical trial

Objective:To determine whether total or partial etching procedures influence the appearance of white spot lesions (WSLs).Materials and Methods:This split-mouth, double-blind, controlled, randomized study included 20 patients (mean age 16.75 years), who had class I malocclusion, mild crowding, and satisfactory oral hygiene. A total of 40 maxillary quadrants were randomly allocated to be treated using a total etching (TE) or partial etching (PE) protocol. Quantitative light fluorescence images were captured at the beginning and at 3 (T1) and 6 (T2) months after beginning orthodontic treatmen, as well as when the debonding phase of orthodontic treatment was complete (T3). The presence of pre- and posttreatment WSLs was assessed with quantitative light fluorescence software and analyzed with Student''s t-test.Results:The analyses showed that, at T2, the total etching group had significantly higher ΔQ and A scores than the partial etching group (P < .05). The ΔF scores increased significantly at all timepoints in the TE group, but only at T1 and T3 in the PE group. However, no differences were noted at T3 between the TE and PE groups (P > .05). The inclusion of only right-handed people may have limited the generalizability of the findings. The absence of analyses of the plaque and gingivitis scores of patients was another limitation of this study.Conclusions:WSL formation was observed mostly in maxillary lateral incisor teeth irrespective of the etching technique. Although PE seems to be more successful in the first 6 months, no difference was observed between PE and TE in the long term for WSL formation.     

The efficacy of fluoride varnish vs a filled resin sealant for preventing white spot lesions during orthodontic treatment:: A randomized clinical trial

ObjectivesTo compare the efficacy of casein phosphopeptide (CPP)-amorphous calcium phosphate (ACP) MI Varnish (GC America, Inc, Alsip, IL) and ProSeal (Reliance Orthodontic Products, Itasca, IL) sealant in preventing the development of white spot lesions (WSLs) in orthodontic patients.Materials and MethodsThis prospective randomized clinical trial included 40 orthodontic patients 12–17 years of age. One group had sealants placed on their anterior maxillary teeth, with reapplications every 3 months. The other group had MI Varnish applied every 4–6 weeks. WSL formation and oral hygiene were evaluated at the initial appointment before bonding (T1) and 12 months later (T2). Standardized digital photographs were analyzed using the enamel decalcification index (EDI). Statistical comparisons were made using independent and paired-sample t-tests as well as chi-square tests.ResultsIn this trial, 43% of patients and 15% of teeth developed new WSLs. Lateral incisors showed the highest incidence of decalcification and WSL formation. WSL formation and EDI score increases during treatment were significantly greater in the gingival region than in the mesial, distal, or incisal regions. Of the EDI scores at T2, 93.8% were 0 and 5.5% were 1. Poor oral hygiene at T2 showed a high positive predictive value (76%) for the development of WSLs. There were no statistically significant between-group differences for the development of WSLs.ConclusionsMI Varnish and ProSeal sealant provided similar levels of protection during the first 12 months of fixed orthodontic treatment. The severity of the WSLs that developed was minimal. WSLs were most likely to develop on lateral incisors and in the gingival regions of teeth, especially among patients with poorer oral hygiene.     

Evaluation of staining and color changes of a resin infiltration system

Objective:To analyze the staining and color changes of a resin infiltrant system used for management of white spot lesions (WSLs).Materials and Methods:WSLs were artificially created on left buccal halves of 48 extracted human teeth. These sites were then treated with resin infiltration (RI) while the right halves of the teeth remained as nonresin (NRI) areas. Six groups were formed (n = 8 teeth/group) and were exposed to the following: red wine, coffee, orange juice, combined staining agents, accelerated aging, and distilled water for 1 week. The teeth were then polished with a prophy cup and polishing paste. Color properties were assessed using a spectrophotometer at baseline (T0), after each exposure (T1), and after polishing (T2). Color difference (ΔE*) was calculated between each time point for both halves of the teeth (RI and NRI). Data were analyzed with a two-way analysis of variance with presence of resin infiltration and staining agents as the main effects for each time point pair. Multiple comparisons were made with a Bonferroni post hoc test. The level of significance was set at P < .05.Results:The red wine and combined staining agent groups caused the greatest color change between all intervals (P < .05). Significant interactions were recorded between resin infiltration application and staining agents at all time periods (P < .05). The presence of resin infiltration as a main effect did not affect color change between T0 and T2 (P > .05).Conclusions:RI areas showed higher staining susceptibility than did NRI areas. However, prophylaxis had a strong effect on reversing the discoloration of both RI and NRI areas.     

Tooth color change due to different etching and debonding procedures

Objectives:To compare the effects of different etching techniques, 12–, 24–bladed tungsten carbide burs, and polishing discs on tooth color changes during orthodontic treatment.Materials and Methods:59 individuals (mean age: 15.20 ± 1.59 years) were divided into four groups: 37% phosphoric acid and adhesive primer was used in Groups I and II whereas self–etch primer was used in Groups III and IV for enamel preparation. After orthodontic treatment, residual adhesives were cleaned with 12–bladed tungsten carbide burs in Groups I and III, while 24–bladed tungsten carbide burs were used in Groups II and IV. All teeth were polished with medium and fine Sof–Lex XT discs (3M ESPE, St Paul, Minnesota). Color measurements were taken from upper incisors and canines at pretreatment (T0), after cleaning with tungsten carbide burs (T1) and polishing with discs (T2). Wilcoxon test was used for evaluation of L*, a*, b* changes and Kruskal–Wallis for intergroup comparison of color changes.Results:L*, a*, b* values, except a* at Groups I, II, IV, and b* at Group III, changed significantly (P < .05). Groups III and IV showed significantly different color alterations from T0 to T1 (P < .05). After polishing, tooth color alterations were not significantly different among the groups.Conclusions:In self–etch bonding groups, a 12–bladed tungsten carbide bur caused less color change than the 24–bladed tungsten carbide bur. Orthodontic treatment resulted with visible and clinically unacceptable tooth color alterations regardless of the enamel preparation and clean–up techniques. Polishing reduced the effect of tungsten carbide burs, but did not affect the total influence of orthodontic treatment on the tooth color.     

Combined effects of repeated oral hygiene motivation and type of toothbrush on orthodontic patients: A blind randomized clinical trial

Objective:To investigate the effects on plaque index (PI) scores of manual or electric toothbrush with or without repeated oral hygiene instructions (OHI) and motivation on patients wearing fixed orthodontic appliances.Materials and Methods:One month after the orthodontic fixed appliance bonding on both arches, 60 patients were randomly assigned to four groups; groups E₁ (n  =  15) and E₂ (n  =  15) received a powered rotating-oscillating toothbrush, and groups M₁ (n  =  15) and M₂ (n  =  15) received a manual toothbrush. Groups E₁ and M₁ received OHI and motivation at baseline (T0) and after 4, 8, 12, 16, and 20 weeks (T4, T8, T12, T16, and T20, respectively) by a Registered Dental Hygienist; groups E₂ and M₂ received OHI and motivation only at baseline. At each time point a blinded examiner scored plaque of all teeth using the modified Quigley-Hein PI.Results:In all groups the PI score decreased significantly over time, and there were differences among groups at T8, T12, T16, and T20. At T8, PI scores of group E₁ were lower than those of group E₂, and at T12, T16, and T20, PI scores of groups M₁ and E₁ were lower compared to those of groups M₂ and E₂. A linear mixed model showed that the effect of repeated OHI and motivation during time was statistically significant, independently from the use of manual or electric toothbrush.Conclusions:The present results showed that repeated OHI and motivation are crucial in reducing PI score in orthodontic patients, independent of the type of toothbrush used.     

Spectrophotometric analysis of crown discoloration induced by MTA- and ZnOE-based sealers

Crown discoloration can be induced by root canal sealer remnants following root canal treatment.

Objective:

The aim of this study was to evaluate chromatic alterations in human tooth crowns induced by a Mineral Trioxide Aggregate-based sealer (MTA Fillapex^® and a commonly used ZnOE-based sealer (Roth-811). The tested null hypothesis was that the application of the materials did not induce clinically perceptible crown discoloration (Ho: CIE color difference ΔE<3.7).

Material and Methods:

Forty five fully developed, intact, mandibular third molars were sectioned 1 mm below the cemento-enamel junction. The pulp chambers were chemomechanically debrided via the cervical access. The specimens were randomly assigned into three groups Group 1: MTA Fillapex, Group 2: Roth 811, Group 3: Negative control (unfilled) and immersed in individually marked vials containing distilled water up to the cervix (37±1º C). The spectral reflectance lines were recorded by utilizing a UV-VIS spectrophotometer equipped with integration sphere in the visual spectrum at baseline, 1 week, 1 and 3 months after material placement. Data were transformed into values of the CIE L*a*b* color system and the corresponding ΔE values were calculated. Statistical analysis was performed using two-way mixed ANOVA models, at p=0.05 level of significance.

Results:

A statistically significant increase in a* and b* chromatic parameters of the MTA Fillapex Group was measured. However, ΔE values did not exceed the human eye perceptibility threshold (set at ΔE<3.7) during the experimental period (ΔEt3=2.88). In Roth-811 Group, a statistically significant decrease in L* and a statistically significant increase in a* and b* chromatic parameters was measured, during all observation periods. Resultant ΔE values exceeded the human eye perceptibility threshold after 1 week (ΔEt1=5.65).

Conclusions:

Application of MTA Fillapex in tooth crowns resulted in minimal color alterations, while Roth 811 induced severe discoloration, in vitro. It could be suggested that, in terms of aesthetics, the use of MTA Fillapex appears to be favorable.     

Evaluation of canting correction of the maxillary transverse occlusal plane and change of the lip canting in Class III two-jaw orthognathic surgery

Objective:To compare the effect of canting correction in anterior maxillary transverse occlusal planes (AMTOP) and posterior maxillary transverse occlusal planes (PMTOP) on the change of lip canting (LC) in two-jaw surgery (TJS) cases.Materials and Methods:The samples consisted of eight young adult patients (three males and five females, mean age  =  24.1 ± 4.5 years) who had skeletal Class III malocclusion (CIII), facial asymmetry (FA), and LC and who underwent TJS. Two-dimensional lateral and posteroanterior cephalograms and three-dimensional facial scanning taken 1 week before (T1) and 6 months after TJS (T2) were combined using the Morpheus 3D program. Six linear and angular variables were measured and statistically analyzed.Results:When comparing the values of the linear and angular variables at the T1 and T2 stages there was significant canting correction of AMTOP (1.7 mm vs −0.3 mm; 3.0° vs 0.1°), PMTOP (3.5 mm vs 0.1 mm, 3.3° vs −0.1°), and LC (3.0 mm vs 0.7 mm, 4.7° vs 2.1°) (all P < .05). Although the angular change ratios (ΔLC/ΔAMTOP and ΔLC/ΔPMTOP) did not exhibit a significant difference (0.99 vs 0.83), the linear change ratio of ΔLC/ΔAMTOP was significantly higher than that of ΔLC/ΔPMTOP (1.67 vs 0.74, P < .05). The angular change of ΔLC showed a significant correlation with ΔAMTOP (r²  =  0.64; P < .05). However, the linear change of ΔLC was significantly correlated with both the angular and linear changes of ΔAMTOP (r²  =  0.62 and 0.66; both P < .05). Therefore, the amount of LC change was more related to the canting correction of AMTOP than to that of PMTOP.Conclusion:In TJS cases with CIII, FA, and LC, the amount of canting correction of the AMTOP should be considered to predict the actual LC change.     

Color stability and fluorescence of different orthodontic esthetic archwires

Objective:To evaluate the color stability of six esthetic archwires at different time periods and their fluorescence.Materials and Methods:Samples were evaluated after 7, 14, and 21 days of immersion in staining solution. Color measurements were performed by means of a spectrophotometer according to the Commission Internationale de I''Eclairage L*a*b* system, and color changes (ΔE*) and National Bureau of Standards units were computed. The fluorescence of as-received samples was evaluated by two observers and compared with that of a bovine central incisor. Statistical differences were investigated using analysis of variance and Tukey''s post hoc test.Results:All brands showed statistically significant color change after 21 days (ΔE* from 1.88 to 12.06). The Optis archwire (fiber-reinforced composite) presented the highest color alteration, although staining was observed only near its ends. The Trianeiro archwire (coated nickel-titanium) and the Ortho Organizers archwire (coated stainless steel) presented with less color change. The Optis archwire was the only one that presented with fluorescence similar to that of bovine teeth.Conclusions:All esthetic archwires assessed showed clinically noticeable color change after 21 days in staining solution. The optical properties of currently available esthetic archwires may not yet be ideal.     

A novel method for testing the veridicality of dental colour assessments

The Commission Internationale de l'Eclairage (CIE) L*a*b* three-dimensional coordinates suggest strong correlations between the data of a* (red-green axis) and b* (blue-yellow axis), as both are located on the same plane in the model and should therefore show a strong dependency. In order to assess the veridicality of colour determinations, the null hypothesis of no significant changes in CIE-a*/b* coherences of dental colours following a colour or lightness change induced by external dental bleaching was tested. Values from 231 extracted anterior teeth were assessed using the digital photographic CIELAB recalculation method. Teeth were then assigned to three groups (n = 77) with contrasting baseline CIE-L* values. Group A served as the control with no alteration in dental colour. The specimens in the two other groups were altered in colour or lightness employing treatment with either 15 per cent carbamide peroxide (group B) or 38 per cent hydrogen peroxide (group C). Pearson's pairwise correlation coefficient of CIE-L*; a*, CIE-L*; b*, and CIE-a*; b* were calculated for assessments at baseline (T0) and after 2 (T1), 4 (T2), 12 (T3), and 24 (T4) weeks. The correlations of a* and b* from T0 to T4, in relation to group A, were stable, with coefficients of 0.78→0.65→0.65→0.69→0.67. Bleaching-induced colour and lightness changes did not have a significant influence on the a*/b* coherences assessed. A distinctly weaker and inverse relationship was observed between L* and a* values and between L* and b* values in the groups, with correlation coefficients ranging from -0.54 to -0.12. Colour coherences detected at specific points in time were in agreement with theoretical CIE colour coherences. In order to compare the methodology of different colour analyses, the analysis of correlations between CIE-a* and -b* values is advocated as an additional routine test in future CIELAB studies.     

The short-term treatment effects of face mask therapy in Class III patients based on the anchorage device: Miniplates vs rapid maxillary expansion

Objective:To compare the short-term treatment effects of face mask therapy with miniplates (FM-MP) and face mask therapy with rapid maxillary expansion appliance (FM-RME) in growing Class III malocclusion patients with maxillary hypoplasia.Materials and Methods:Twenty patients were allocated into two groups according to the anchorage device: FM-MP group (n  =  10; mean age  =  11.2 ± 1.2 years; miniplates in the zygomatic buttress area) and FM-RME group (n  =  10; mean age  =  10.7 ± 1.3 years; bonded or banded RME). The face mask was applied for 12 to 14 hours/day in both groups with a force of 400 g/side directed 30° downward and forward from the occlusal plane. Lateral cephalograms were taken before (T1) and after FM-MP or FM-RME therapy (T2). Skeletodental and soft-tissue variables were measured. Paired and independent t-tests were performed for statistical analysis.Results:Both groups exhibited significant forward movement of point A and posterior repositioning and opening rotation of the mandible from T2 to T1. The FM-MP group showed significant protraction of orbitale (ΔSNO), and the FM-RME group showed a decrease in overbite and an increase in Björk sum. Comparing the amount of changes between the two groups, the FM-MP group displayed greater forward movement of the maxilla than the FM-RME group (ΔSNA, ΔA to N perp, all P < .05). However, the FM-RME group exhibited a greater opening rotation of the mandible (ΔSNB, Björk sum, all P < .01; ΔPog to N-perp, P < .05) and labioversion of the maxillary incisors (ΔU1-FH, P < .05).Conclusion:FM-MP therapy induces a greater advancement of the maxilla, less posterior repositioning and opening rotation of the mandible, and less proclination of the maxillary incisors than FM-RME therapy.     

Effect of time and pH on physical-chemical properties of orthodontic brackets and wires

Objective:To test the hypothesis that treatment time, debris/biofilm, and oral pH have an influence on the physical-chemical properties of orthodontic brackets and arch wires.Materials and Methods:One hundred twenty metal brackets were evaluated. They were divided into four groups (n  =  30) according to treatment time: group C (control) and groups T12, T24, and T36 (brackets recovered after 12, 24, and 36 months of treatment, respectively). Rectangular stainless-steel arch wires that remained in the oral cavity for 12 to 24 months were also analyzed. Dimensional stability, surface morphology, composition of brackets, resistance to sliding of the bracket-wire set, surface roughness of wires, and oral pH were analyzed. One-way analysis of variance, followed by a Tukey multiple comparisons test, was used for statistical analysis (P < .05).Results:Carbon and oxygen were shown to be elements that increased expressively and in direct proportion to time, and there was a progressive increase in the coefficient of friction and roughness of wires as a function of time of clinical use after 36 months. Oral pH showed a significant difference between group T36 and its control (P  =  .014).Conclusions:The hypothesis was partially accepted: treatment time and biofilm and debris accumulation in bracket slots were shown to have more influence on the degradation process and frictional force of these devices than did oral pH.     

Maxillary incisor inclination of skeletal Class III patients treated with extraction of the upper first premolars and two-jaw surgery: Conventional orthognathic surgery vs surgery-first approach

Objective:To investigate the differences in the amount and pattern of the maxillary incisor (MXI) inclination change in skeletal Class III patients treated with extraction of the maxillary first premolars (MXP1) and two-jaw surgery (TJS) between conventional orthognathic surgery (COS) and surgery-first approach (SFA).Materials and Methods:The study included 60 skeletal Class III patients who had normal maxillary position, prognathic mandible, and mild crowding in the maxillary arch (≤4 mm). The patients were divided into group 1 (COS, n  =  36) and group 2 (SFA, n  =  24). Lateral cephalograms were taken before treatment (T0), 1 month before surgery (T1), within 1 month after surgery (T2), and after debonding (T3) for COS patients and at T0, T2, and T3 for SFA patients. After measurement of the skeletodental variables, statistical analyses were performed.Results:During T0–T2, the amount of MXI inclination change (ΔU1-SN) in group 1 was significantly larger than that in group 2 (−12.8° vs −4.4°; P < .001). During T2–T3, ΔU1-SN in groups 1 and 2 occurred in opposite directions (3.8° vs −5.9°; P < .001). However, the total amount of ΔU1-SN during T0–T3 was not different between groups 1 and 2 (−9.0° vs −10.3°). At T3 the U1-SN values for groups 1 and 2, respectively, moved closer to normal according to the values of the normal range rate (all 83%), relative percentage ratio (102.4% and 100.1%), and achievement ratio (77.7% and 97.8%).Conclusions:The results of this study might provide basic data for predicting the amount and pattern of MXI inclination change in SFA for skeletal Class III TJS patients.     

Short-term postorthodontic changes in the absence of retention

Objective:To evaluate short-term postorthodontic tooth movement without retention.Materials and Methods:Thirty consenting patients participated in the study. At the end of active treatment (T₁), final archwires were removed while leaving the fixed appliances on, and alginate impressions were taken. Four weeks later (T₂) a second set of impressions was taken. A clinical examination performed at T₂ determined if the fixed appliances could be removed or if additional treatment was required. Based on the examination, patients were divided into two groups. Patients in group I (n  =  13) had their fixed appliances removed, while those in group II (n  =  17) required additional treatment. The American Board of Orthodontics'' Objective Grading System scores and the following six variables were measured on plaster casts at T₁ and T₂: maxillary and mandibular crowding or spacing, overbite, overjet, and mandibular intercanine and intermolar widths. Data were analyzed to detect potential changes from T₁ to T₂ and to evaluate differences between the groups.Results:Mandibular crowding, overjet, and interproximal contacts worsened for the entire sample, while marginal ridges, occlusal contacts, and total American Board of Orthodontics scores improved. No statistically significant changes were found within group I from T₁ to T₂. Mandibular crowding, overbite, overjet, alignment/rotations, and interproximal contacts worsened within group II from T₁ to T₂, while marginal ridges and occlusal contacts improved. Significant differences were noted between the groups in terms of alignment/rotations, interproximal contacts, and mandibular intercanine width.Conclusion:Short-term postorthodontic tooth movement without retainers demonstrated improvement in specific characteristics of the occlusion but negatively affected alignment and interproximal contacts in the sample.     

Effect of Aging on the Microstructure and Optical Properties of Translucent ZrO 2 Ceramics

ObjectivesThe development and placement of translucent zirconia ceramics on the dental materials market is in full swing. This research aimed to investigate how aging protocols affect the microstructure, color parameters and translucency of a new-generation monolithic zirconia ceramic.Material and methodsTranslucent zirconia ceramics KATANA-Zirconia STML with different surface treatments (as sintered - control, glazed, polished) was tested using two aging protocols (hydrothermal degradation in autoclave at 134 °C and 2 bars for three hours, chemical degradation in four-percent acetic acid at 80 °C for 16 hours) in order to examine phase composition using X-ray diffraction analysis and ΔE, ΔL and ΔC color parameters through spectrophotometry. The translucency parameter (TP) was calculated using parameters L*, a* and b* on a black and white surface.ResultsRegardless of the surface treatment, aging protocols did not cause a tetragonal-to-monoclinic phase transformation, although hydrothermal degradation in the autoclave transformed the hybrid tetragonal-cubic structure of all specimens to a tetragonal one. All polished and glazed specimens during chemical degradation demonstrated a significant color change ΔE. Lightness ΔL significantly changed in polished specimens aged in the autoclave. In all specimens, ΔC underwent a change manifested through statistically insignificant yellowing. None of the aging protocols altered the translucency of specimens.ConclusionsAging, regardless of the final surface treatment, did not manifest a monoclinic phase in the specimens. A tetragonal-cubic microstructure dominates. Unlike polishing, glazing the surface of translucent zirconia ceramics contributed to minor changes in color, lightness and chromaticity. The translucency of translucent zirconia ceramics remains stable regardless of aging and surface treatment.     

Quantitative Light-induced Fluorescence-Digital as an oral hygiene evaluation tool to assess plaque accumulation and enamel demineralization in orthodontics

Objective:To assess the use of Quantitative Light-induced Fluorescence-Digital as an oral hygiene evaluation tool during orthodontic treatment.Materials and Methods:In this prospective, randomized clinical trial, 33 patients undergoing fixed orthodontic appliance treatment were randomly allocated to receive oral hygiene reinforcement at four consecutive appointments using either white light (WL) or Quantitative Light-induced Fluorescence-Digital (QLF) images, taken with a device, as visual aids. Oral hygiene was recorded assessing the QLF images for demineralization, by fluorescence loss (ΔF), and plaque coverage (ΔR30). A debriefing questionnaire ascertained patient perspectives.Results:There were no significant differences in demineralization (P  =  .56) or plaque accumulation (P  =  .82) between the WL and QLF groups from T0 to T4. There was no significant reduction in demineralization, ΔF, in the WL, or the QLF group from T0–T4 (P > .05); however, there was a significant reduction in ΔR30 plaque scores (P < .05). All the participants found being shown the images helpful, with 100% of the QLF group reflecting that it would be useful to have oral hygiene reinforcement for the full duration of treatment compared with 81% of the WL group (OR 2.3; P < .05).Conclusions:Quantitative Light-induced Fluorescence-Digital can be used to detect and monitor demineralization and plaque during orthodontics. Oral hygiene reinforcement at consecutive appointments using WL or QLF images as visual aids is effective in reducing plaque coverage. In terms of clinical benefits, QLF and WL images are of similar effectiveness; however, patients preferred the QLF images.     

Color Stability of Dental Composites after Immersion in Beverages and Performed Whitening Procedures

ObjectivesThe study aimed to compare the color stability of two different light-cured composites after immersion in three liquids and the effectiveness of 16% carbamide peroxide (CP) in removing the discoloration.Material and methodsColor stability of a microhybrid (Z250, 3M ESPE) and nanocomposite (Z550, 3M ESPE) was evaluated after immersion in instant coffee, tea, Coca-Cola, and deionized water as a control group (n=5). Samples were kept in liquids for four hours daily at 37°C for 30 days. Furthermore, 16% CP was applied for the following 14 days, simulating night whitening. A digital spectrophotometer was used for color measurement based on the CIEL*a*b* color coordinates. The color changes (∆E) were measured at baseline, after immersion in the beverages, and also after the teeth whitening procedure. Mixed and factorial ANOVA followed by Bonferroni’s post-hoc test were used for statistical evaluation (p≤0.05).ResultsTested resin composites showed a color change over the acceptability threshold (ΔE*> 3.48) after immersion in coffee and tea. Nanocomposite reported a significant increase in discoloration in coffee after 30 days (p <0.05). The color of both materials significantly changed (p<0.05) along all three L*a*b* axes in coffee and tea to darker, yellow, and red. Whitening with 16% CP was effective in removing external discoloration in both examined composite materials.ConclusionCoffee and tea induced clinically detectable color changes in dental composites tested, with cumulative effects. Whitening represents an efficient method for the removal of surface discoloration in composite restorations.     

Removable dental prostheses and cardiovascular survival: A 15-year follow-up study

ObjectivesIn previous studies, increasing number of teeth predicted better survival and the acute needs for dental treatment predicted mortality. We sought to investigate whether restored dentitions by various removable dental prostheses impact cardiovascular (CVD) longevity.MethodsKuopio Oral Health and Heart study was initiated as a cross-sectional investigation with 256 subjects with diagnosed coronary artery disease [CAD] and 250 age- and sex-matched controls without CAD in 1995–1996. The mean age of both groups was 61, 30% were females. We appended mortality follow-up records to the baseline data and formulated this 15-year follow-up study. We examined the relationship between various types of dental prostheses and cardiovascular mortality by proportional hazard regression analyses. We also explored their correlation to oral and systemic inflammatory markers such as asymptotic dental score and C-reactive protein.ResultsIn a model adjusted for age, sex and smoking, groups having only natural teeth (NT), removable partial denture(s) [PD] and NT, a PD and a full denture [FD], and FD/FD or FD/NT demonstrated the following hazard ratios for mortality (95% confidence interval). NT both arches: 1.00 [reference]; PD and NT: 0.75 [0.22–2.56]; PD and FD: 1.99 [1.05–3.81]; and FD opposed by FD or NT: 1.71 [0.93–3.13], respectively [p for trend = 0.05]. Although statistically not significant, those with PD and NT with mean a number of teeth [N_teeth] of 15.4 had better survival compared with those who had all NT [N_teeth = 22.5]; while those who had FD and PD [N_teeth = 6.5] had shorter longevity than those with FD/FD or FD/NT [N_teeth = 3.5].ConclusionsAlthough not all subgroups of dental prostheses reached significant relationship with CVD mortality, our study suggests that not only the number [quantity] of remaining teeth but their maintenance [quality] removing potential inflammatory foci, such as pericoronitis or retained root tips, may positively impact on cardiovascular survival.