An evaluation of microleakage of various glass ionomer based restorative materials in deciduous and permanent teeth: An in vitro study

AimTo evaluate the microleakage of recently available glass ionomer based restorative materials (GC Fuji IX GP, GC Fuji VII, and Dyract) and compare their microleakage with the previously existing glass ionomer restorative materials (GC Fuji II LC) in primary and permanent teeth.MethodOne hundred and fifty (75 + 75) non-carious deciduous and permanent teeth were restored with glass ionomer based restorative materials after making class I cavities. Samples were subjected to thermocycling after storing in distilled water for 24 h. Two coats of nail polish were applied 1 mm short of restorative margins and samples sectioned buccolingually after storing in methylene blue dye for 24 h. Microleakage was assessed using stereomicroscope.ResultSignificant differences (P < 0.05) were found when inter group comparisons were done. Except when GC Fuji VII (Group III) was compared with GC Fuji II LC (Group II) and Dyract (Group IV), non-significant differences (P > 0.05) were observed. It was found that there was no statistically significant difference when the means of microleakage of primary teeth were compared with those of permanent teeth.ConclusionsGC Fuji IX GP showed maximum microleakage and GC Fuji VII showed least microleakage.     

Compressive strength of two newly developed glass-ionomer materials for use with the Atraumatic Restorative Treatment (ART) approach in class II cavities

ObjectivesThe null-hypotheses tested were that no difference in compressive strength of ART class II cavities exists between those restored with (1) glass-carbomer and a commonly used glass-ionomer; (2) KMEM and the commonly used glass-ionomer and; (3) glass-carbomer and KMEM.Methods100 molar teeth, stratified by size, were randomly allocated to the four test groups. Large ART class II cavities were drilled and restored with Clearfil photoposterior (negative control), Fuji IX (positive control), Glass-carbomer and Ketac? Molar Easymix (KMEM) (experimental groups). Half of the samples in each test group were 5000 times thermocycled between 5 °C and 55 °C, with a 30 s dwell time in each bath and a transfer time of 10 s. The restorations were statically tested at the marginal ridge until failure, using a rounded rectangular testing rod at crosshead speed of 1.0 mm/min. ANOVA and Student's t-test were applied to test for differences between the dependent variable (compressive strength at the final breaking point) and the independent variables (thermocycling and restorative material).ResultsRestorations of Clearfil photoposterior had a statistically significant higher mean compressive strength value at final breaking point than those of the three glass-ionomers tested (p = 0.0001). No thermocycling effect was observed (p = 0.19). ANOVA between the three glass-ionomer materials and mean compressive strength at final breaking point showed no statistically significant difference (p = 0.09).SignificanceClass II ART cavities restored with the newly launched Glass-carbomer and Ketac? Molar Easymix were not significantly more fracture resistant than comparable restorations using the conventional glass-ionomer Fuji IX.     

Water sorption and solubility of core build-up materials

ObjectivesTo investigate the variation in water sorption and solubility across a range of different core build-up materials.MethodsFive materials were tested, four of which are resin-based materials (Grandio Core, Core.X Flow, Bright Flow Core, Speedee) and one resin-modified glass ionomer (Fuji II LC). All specimens (n = 10) were immersed in 10 ml distilled water in individual glass containers and weighed at one week, 14 and 28 days. After a total immersion time of 28 days, 7 specimens were dried to a constant mass, in a desiccator for 28 days. Three samples of each material were not dried, but were left in distilled water for 1 year, to determine the long-term water sorption properties. Specimens were weighed at monthly intervals until 6 months and then at the 9th and 12th months. Each specimen was measured using a digital electronic caliper (Mitutoyo Corporation, Japan).ResultsAfter 28 days immersion, the change in water sorption and solubility of the materials ranged from 12.9 to 67.1 μg/mm³ (P < 0.001) and 0.9–6.4 μg/mm³ respectively (P < 0.001). Except for Fuji II LC, an independent T-test showed significantly higher water sorption and solubility for the other materials after 1-year total immersion in water compared to 1 month (P < 0.05). Using repeated measures ANOVA, all materials showed mass changes over time (1 month) (P < 0.001).SignificanceGrandio Core had the lowest water sorption and solubility among the tested materials. According to the ISO 4049 standards, all the tested materials showed acceptable water sorption and solubility, apart from the water sorption behavior of Fuji II LC.     

Survival of multiple-surface ART restorations using a zinc-reinforced glass-ionomer restorative after 2 years: A randomized triple-blind clinical trial

ObjectiveTo investigate the effectiveness of a new zinc-reinforced glass-ionomer in comparison to a common high-viscous glass-ionomer cement (HVGIC) used in multiple-surface ART-prepared cavities. The hypothesis tested was that the cumulative survival percentage of the new HVGIC is higher than that of the common HVGIC over 2 years.MethodsA randomized triple-blind parallel group clinical trial was used. A total of 218 participants, average age 15.4 years (SD = 0.2), with an occluso-proximal carious lesion in a permanent (pre-) molar were included. Restorations using test (ChemFil Rock) and control (Fuji IX GP) restoratives were placed according to the ART method by four calibrated operators. Restorations were evaluated after one week (baseline), and at 6-, 12-, 18- and 24 months from replicas and coloured photographs according to the ART restoration assessment criteria by two independent evaluators. Restoration survival curves were estimated using the Kaplan–Meier method and difference between dependent and independent variables tested with a Wald (chi-square) test.ResultsThere was a statistically significant difference in cumulative survival percentages between the two types of restorations at 2 years (P = 0.02). A higher percentage of multiple-surface restorations of Fuji IX GP (95.4%) than ChemFil Rock (85.3%) survived. Gender (P = 0.64), operator (P = 0.56) and cavity size (P = 0.81) had no effect on the survival of the type of restoration observed. Type of tooth (P = 0.004) and type of jaw (P = 0.05) showed an effect. Severe wear was the major reason for restoration failure (ChemFil Rock = 7; Fuji IX GP = 1).SignificanceChemFil Rock appears not to be a viable alternative to Fuji IX GP in restoring ART multiple-surface cavities in permanent posterior teeth.     

Effects of different abutment material and surgical insertion torque on the marginal adaptation of an internal conical interface: An in vitro study

PurposeTo evaluate the marginal adaptation at implant–abutment connection of an implant featuring a conical (45° taper) internal hexagonal abutment with a connection depth of 2.5 mm, comparing the performance of two identical abutments of different material (titanium grade-4 and Co-Cr-alloy).MethodsTwenty implants (3.75 mm × 15 mm) were connected to non-matching abutments (5.5 mm × 10 mm) of two different materials (titanium grade-4: n = 10; Co-Cr-alloy: n = 10). The specimens were separately embedded in epoxylite resin, inside copper cylinders, and submerged without covering the most coronal portion (5 mm) of the fixture. Five specimens per group were stressed simulating a surgical 100 Ncm insertion torque, while the others had no torque simulation. All specimens were subjected to a non-axial static load (100 N) in a universal testing machine, under an angle of 30° with respect to the implant axis. Once 100 N load was reached, low shrinkage self-curing resin was injected inside the cylinders, and load was maintained until complete resin polymerization. Specimens were cut and analyzed with optical and scanning-electron-microscope (SEM) to evaluate the marginal adaptation at the implant–abutment connection. Statistical analysis was performed using one-way ANOVA (p = 0.02).ResultsNone of the 20 samples failed. The implant–abutment connection was able to guarantee a good optical seal; SEM analysis confirmed the absence of microgaps.ConclusionsWithin the limits of this study (small sample size, limited time) the marginal adaptation of the implant–abutment connection was not affected by the abutment material nor by the application of surgical insertion torque.     

Measurement of root surface area of permanent teeth in a Chinese population

ObjectivesThe aim of this study was to investigate the relation between the remaining area of periodontal attachment and the attachment levels for each type of permanent teeth in a Chinese population by using micro-computed tomography (micro-CT) scans.DesignA total of 440 extracted permanent teeth (including each tooth type except for the third molars) were collected from a Chinese population and scanned using a micro-CT. The CT data were input into Mimics 15.01 to generate 3D tooth models. To simulate various attachment levels, the roots were virtually cut at 0, 2, 4, 6, 8, and 10 mm from the cemonto-enamel junction (CEJ). The net and percent remaining root surface area (RSA) were measured and calculated, and the data corresponding to attachment level were fitted to a linear function.ResultsA Linear function can perfectly fit in relating the simulated attachment level to the net and percent remaining RSA (R² > 0.99, and p < 0.001 for each tooth type). For net remaining RSA, the slope of the linear function was steepest for maxillary first molars (b₁ = −39.32) and least steep for mandibular central incisor (b₁ = −13.08); whereas for the percentage of remaining RSA, the slopes (b₁) were relatively within a narrow range, from −7.40 (maxillary canine) to −9.64 (maxillary first molars).ConclusionMicro-CT offers simple and precise technique for quantitative analysis of the RSA. The total amount and vertical distribution of the RSA varied by tooth type. Linear formulas can perfectly describe the relation between the attachment level and the net and percent remaining RSA.     

Assessment of gingival biotype and facial hard/soft tissue dimensions in the maxillary anterior teeth region using cone beam computed tomography

ObjectiveThis study sought to assess the relationship between facial gingival and bone dimensions in maxillary anterior teeth region using cone beam computed tomography (CBCT).DesignThis study assessed 621 maxillary anterior teeth in 144 patients. In the sagittal plane, facial bone thickness (BT) and gingival thickness (GT) were measured at the crestal level and at 2, 4 and 6 mm apical to the cementoenamel junction (CEJ). The dentogingival complex (DGC) dimensions and the distance from the CEJ to bone crest were also measured on CBCT scans. To determine the gingival biotype, GT at 2 mm apical to the gingival margin was measured and GT <1.5 mm was categorized as thin while GT ≥1.5 mm was categorized as thick. The data were analyzed using SPSS version 21 via repeated measures ANOVA and the Cochrane’s Q, chi-square and independent samples t-tests.ResultsThe BT around the maxillary central and lateral incisors and canine teeth at 4 and 6 mm apical to the CEJ was significantly different in thick and thin gingival biotypes (P < 0.05). The mean GT at 2 and 4 mm apical to the CEJ was significantly different around central and lateral incisors (P < 0.05). Thickness of crestal bone was significantly different between the two gingival biotypes around central and lateral incisors (P < 0.05).ConclusionThe two gingival biotypes had significantly different mean BT; different biotypes and their relationship to BT varied around anterior maxillary teeth.     

Retrospective investigation of the remaining teeth status of patients with implant-supported fixed partial dentures in unilateral free-end edentulism

PurposeThis study aimed to compare the various complication-free rates and survival rates of remaining teeth among implant-supported fixed dentures (IFDs), removable partial dentures (RPDs) and no-restoration (NR) patients with unilateral free-end edentulism.Material and methodsThe study subjects were selected among those who received prosthodontic treatment at Okayama University Dental Hospital for their unilateral free-end edentulism (2 or 3 missing teeth). Thirty-three patients were included in the IFD group, 41 matched patients in the RPD group, and 10 patients who received RPDs but refused their use were regarded as NR group. The remaining dentition was classified into five subcategories in relation to the missing portion: adjacent teeth to the missing portion (AD), contralateral posterior dentition in the same jaw (CS) and in the opposite jaw (CO), ipsilateral opposing posterior dentition (IO), and anterior dentition (AN). Complications were defined as tooth extraction, periodontal lesions, periapical lesions or loss of retention of the prosthesis and were assessed by one examiner based on the hospital chart records.ResultsThe cumulative complication-free rates in the remaining teeth were significantly different among each of the three groups (p < 0.01), with a significantly lower incidence rate in the IFD group. Regarding the cumulative survival rate of the remaining teeth, there was a significant difference only between IFD and NR group (p = 0.01), especially in the CO region (p = 0.04).ConclusionsStable posterior occlusal support obtained with IFD treatment for unilateral free-end edentulism may reduce the incidence of complications in the remaining teeth, by decreasing the adverse mechanical stress.     

Prevalence of apical periodontitis and quality of root canal treatment in an adult Palestinian sub-population

PurposeThe aim of this study was to determine the prevalence of apical periodontitis and the technical quality of root canal fillings in a Palestinian sub-population.MethodsThe panoramic radiographs of 258 patients (142 females, 116 males) attending dental clinics in 2010 were examined to identify the presence of apical lesions associated with any remaining teeth, excluding third molars. The technical quality of root canal fillings was also evaluated by assessing apical extension from the radiographic apex. The panoramic radiographs were taken by a well-trained radiology assistant and evaluated by a radiologist and an endodontist. Statistical analysis was performed with the chi-square test with a significant level set at P < 0.05%.ResultsOf 6482 teeth examined radiographically, 978 (15.1%) had radiographic signs of apical periodontitis (AP). The prevalence of AP was 8.3% in teeth without filled roots and 59.5% (509/855) in root canal-treated teeth. The prevalence of AP and endodontic treatment increased with age and differed significantly (p < 0.05) between males and females. The majority (74.5%) of root canal fillings was performed inadequately, and most (77.2%) inadequate fillings were >2 mm short of the radiographic apex. The presence of AP was correlated significantly with poorly executed root canal fillings (p < 0.05).ConclusionsThe present study found a high prevalence and incidence of AP in association with root-filled teeth. The technical quality of many root canal treatments was unacceptable.     

Clinical performance and SEM marginal quality of extended posterior resin composite restorations after 12 years

ObjectiveTo investigate the clinical behavior of two different resin-based restorative systems in extended Class II cavities in a controlled prospective split-mouth study over 12 years and to assess marginal quality under a SEM using epoxy replicas.MethodsThirty patients received 68 resin composite restorations (Solobond M + Grandio: n = 36; Syntac + Tetric Ceram: n = 32) by one dentist in a private practice. 35% of cavities revealed no enamel at the bottom of the proximal box, 48% of cavities provided <0.5 mm remaining proximal enamel. Restorations were examined according to modified USPHS criteria at baseline, and after six months, one, two, four, six, eight, 10, and 12 years. Expoxy replicas of 21 restoration pairs were analysed under a SEM at 200× magnification regarding marginal quality.ResultsAt the 12-years recall, 59 of the original 68 restorations in 27 of 30 patients were available (drop out 13%). Two restorations failed due to cusp fracture (Tetric Ceram) and marginal fracture (Grandio). The overall success rate of all restorations was 97.1% (Kaplan–Meier survival algorithm) with no differences between the two materials (p = 0.923). After 144 months of clinical service, restorations in molars performed worse than in premolars regarding the integrity of restoration and tooth (p < 0.05) being detected as wear, chippings, and cracks. Beyond the 4-year recall, marginal staining significantly increased. SEM evaluation of replicas revealed that perfect margin (49% baseline vs. 10% after 12 years), overhang (13% at baseline vs. 3% after 12 years), negative step formation (34% at baseline vs. 75% after 12 years), and marginal fractures (0% at baseline vs. 6% after 12 years) significantly changed during the evaluation period (p < 0.001).SignificanceExtended direct resin composite restorations performed satisfactorily over 12 years of clinical service. SEM analysis delivered qualitative data regarding marginal deterioration over time.     

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.     

Tooth sensitivity and efficacy of in-office bleaching in restored teeth

ObjectivesThe aim of this clinical trial was to evaluate efficacy (BE) and tooth sensitivity (TS) of in-office bleaching with a 35% hydrogen peroxide (HP) in patients with aesthetic restorations.MethodsHydrogen peroxide 35% was applied in two sessions, of three 15 min applications, in 15 patients with upper anterior sound teeth (S) and 15 with aesthetic restorations (R). The colour was recorded at baseline, one week and 6 months after treatment completion. Patients recorded TS on a 0–4 scale. The BE was evaluated by two-way ANOVA and Tukey's tests (α = 0.05). The percentage of patients with TS was evaluated by Fisher's exact test and TS intensity of treatments was compared with Mann–Whitney U-test (α = 0.05).ResultsAll participants experienced TS at least once during treatment. Higher TS intensity was observed in R (1.5 [1/1.75]) compared to S (0.5 [0/1.25]) during the bleaching (p < 0.05). S and R demonstrated similar tooth colour enhancement compared to baseline (p < 0.05) and both presented colour stability after 6 months of evaluation (p > 0.05).ConclusionsThe in-office bleaching with 35% HP was effective in patients with aesthetic restorations, however, a higher intensity of TS was observed during the bleaching protocol.Clinical relevanceIn-office dental bleaching can be performed in patients with adhesive restorations promoting satisfactory results; however, it can promote higher intensity of sensitivity compared to patients with sound teeth.     

Effects of layering techniques on the micro-tensile bond strength to dentin in resin composite restorations

ObjectivesThe purpose of this work was to investigate the effects of layering techniques in resin composite restorations on the micro-tensile bond strength to the dentin of the occlusal cavity.MethodsHuman premolars were extracted and randomly divided into four groups. The occlusal enamel was then removed to expose a flat superficial dentin surface. Cavities 3.5 mm long and 3.5 mm wide were prepared to a depth 3 mm below the dentin surface. The adhesive Single Bond was applied according to the manufacturer's instructions. The teeth were then restored with Z100 resin composite as follows: Group 1 was restored in horizontal increments (three layers). Groups 2 and 3 were restored in different oblique increments (three layers). Group 4 was restored in oblique increments (four layers). After 24 h storage at 37 °C in water, all the teeth were sectioned to obtain bar-shaped specimens with a bonded surface area of approximately 0.9 mm × 0.9 mm. Dentin micro-tensile bond strength was measured at a crosshead speed of 0.5 mm/min. The results obtained were statistically analyzed using one-way ANOVA and SNK test at a significance level of P = 0.05. All fractures were then observed under a scanning electron microscope (SEM).ResultsThe results showed that there is a significant difference between the strength of the micro-tensile bonds to the dentin of occlusal cavities depending on which of the four layering restorative techniques was used (P < 0.01). SEM observation showed that failure patterns were most evidently interfacial cohesive failure.SignificanceLayering techniques in resin composite restorations affected the micro-tensile bond strength between the resin composite and the dentin. But the outcomes related to only Single Bond, as the same using other adhesives might have different outcomes.     

Long-term nanomechanical properties and gelatinolytic activity of titanium tetrafluoride-treated adhesive dentin interface

ObjectiveThis study investigated the effects of dentin pretreatment with 2.5% titanium tetrafluoride (TiF₄) on nanomechanical properties, and the in situ gelatinolytic activity of the dentin–resin interface, for up to 6 months.MethodsTwenty-four human teeth were prepared by exposing occlusal flat dentin surfaces, and were randomly assigned to experimental groups, according to application or non-application of a TiF₄ pretreatment, and to the adhesive systems (Clearfil SE Bond or Scotchbond Universal). Resin composite (Filtek Supreme Ultra) was built up incrementally on the teeth in all the groups. Then, the specimens were sectioned and randomly selected for evaluation at 24 h, 3 months and 6 months of storage time. The reduced modulus of elasticity (E_r) and the nanohardness of the underlying dentin, as well as the hybrid layer and the adhesive layer were measured using a nanoindenter. Gelatinolytic activity at the dentin–resin interfaces was assessed by in situ zymography using quenched fluorescein-conjugated gelatin at 24 h and 6 months. Statistical analyses were performed with ANOVA and Tukey’s tests.ResultsThere were no differences in E_r and nanohardness values between adhesives systems and pretreatment (p = 0.1250). In situ zymography showed significantly higher gelatinolytic activity after 6 months for all the experimental groups (p = 0.0004), but no differences between the adhesive systems (p = 0.7708) and the surface pretreatment (p = 0.4877). Significance: Dentin pretreatment with 2.5% TiF₄ followed by self-etching adhesive systems did not influence nanomechanical properties or gelatinolytic activity of the adhesive–dentin interface layers, over time.     

Observations on fluid flow from exposed dentine in primary teeth: An in vitro study

ObjectiveTo investigate fluid flow through dentine in primary teeth in vitro using the replica technique, and to compare the results with those obtained from permanent dentine.DesignThe experiments were carried out on 22 extracted, mandibular, primary, incisor teeth. The incisal edge was removed to 1 mm below the dentino-enamel junction and half the exposed surface etched with phosphoric acid. The exposed dentine was blotted dry and the pressure in the pulp cavity held at 0, 15, 30 or 45 cm H₂O above atmospheric for 30 s. Fluid that accumulated on the dentine surface was recorded with impression material and a replica made with epoxy resin which was examined in a scanning electron microscope.ResultsStructures resembling fluid droplets were present in the replicas of unetched dentine in all 22 teeth, and at all the pulpal pressures tested. The droplets formed at 45 cm H₂O were significantly larger (median diam., 5.14 mm; interquartile range, 3.26 mm; Friedman repeated measures analysis of variance on ranks (RMAVR) and Tukey test) than those formed at other pressures. There was no evidence of droplets in the replicas of etched dentine with any of the pulpal pressures.ConclusionsThese results demonstrate that fluid will tend to flow from dentine in deciduous teeth when it is exposed. They are similar to those obtained in a previous study in this laboratory on permanent teeth. The fact that fluid droplets were absent from etched dentine suggests that, after being blotted, the etched dentine matrix absorbed fluid that tended to flow out through the dentinal tubules.     

Marginal and internal fits of fixed dental prostheses zirconia retainers

ObjectivesCAM (computer-aided manufacturing) and CAD (computer-aided design)/CAM systems facilitate the use of zirconia substructure materials for all-ceramic fixed partial dentures. This in vitro study compared the precision of fit of frameworks milled from semi-sintered zirconia blocks that were designed and machined with two CAD/CAM and one CAM system.MethodsThree-unit posterior fixed dental prostheses (FDP) (n = 10) were fabricated for standardized dies by: a milling center CAD/CAM system (Etkon), a laboratory CAD/CAM system (Cerec InLab), and a laboratory CAM system (Cercon). After adaptation by a dental technician, the FDP were cemented on definitive dies, embedded and sectioned. The marginal and internal fits were measured under an optical microscope at 50× magnification. A one-way analysis of variance (ANOVA) was used to compare data (α = 0.05).ResultsThe mean (S.D.) for the marginal fit and internal fit adaptation were: 29.1 μm (14.0) and 62.7 μm (18.9) for the milling center system, 56.6 μm (19.6) and 73.5 μm (20.6) for the laboratory CAD/CAM system, and 81.4 μm (20.3) and 119.2 μm (37.5) for the laboratory CAM system. One-way ANOVA showed significant differences between systems for marginal fit (P < 0.001) and internal fit (P < 0.001).SignificanceAll systems showed marginal gaps below 120 μm and were therefore considered clinically acceptable. The CAD/CAM systems were more precise than the CAM system.     

Impact of glycemic control on oral health status in type 2 diabetes individuals and its association with salivary and plasma levels of chromogranin A

ObjectiveTo evaluate the effect of glycemic control status in type 2 diabetes mellitus (T2DM) individuals on clinical oral health indicators and to compare the concentrations of plasma and salivary chromogranin A (CHGA) among nondiabetic subjects and T2DM patients, exploring their associations.DesignIn this cross-sectional study, 32 patients with controlled T2DM, 31 with poorly controlled T2DM and 37 nondiabetic subjects underwent a clinical and periodontal examination. CHGA concentrations were determined in saliva and plasma with ELISA.ResultsPoorly controlled T2DM group exhibited significantly higher mean buffering capacity, plaque index and bleeding on probing than other groups (P < 0.05). No difference was found to DMFT (decayed, missed and filled teeth) index between groups. Sites with clinical attachment loss (CAL) of 4 and 5–6 mm were significantly higher in both diabetic groups compared to control group (P < 0.05). Poorly controlled T2DM group had significantly higher sites with CAL ≥ 7 mm than other groups (P = 0.001). Significantly higher plasma and salivary CHGA levels were found in T2DM groups (P < 0.05). In both diabetic groups, probing depths 5–6 mm and CAL 5–6 mm were associated with higher salivary CHGA concentration (P < 0.05).ConclusionsThe findings revealed that T2DM patients were more prone to periodontal tissue damage than to caries risk. The results also provide some evidence that the degree of attachment loss deteriorates significantly with poor glycemic control in T2DM (CAL ≥ 7 mm). Moreover, the results suggest that high concentrations of salivary CHGA are associated with worse periodontal parameters and T2DM, and this could be related to the pathogenesis of both diseases.     

Influence of mandibular residual ridge resorption on objective masticatory measures of lingualized and fully bilateral balanced denture articulation

PurposeTo assess the influence of mandibular residual ridge resorption (RRR) on objective masticatory measures of two occlusal schemes: lingualized occlusion (LO) and fully bilateral balanced articulation (FBBA).MethodsThe enrolled patients (n = 22) were randomly allocated one set of complete dentures with either LO or FBBA. Maximum occlusal force, masticatory performance (by the MPI), and mandibular movements were measured at 3- and 6-month follow-ups. Mandibular RRR was assessed as the sum of the mandibular bone height at the midline, first premolar region, and least vertical height region, and from the mental foramen to the alveolar crest, measured on panoramic radiographs; the treatment groups were subclassified into severe or moderate RRR subgroups by the value of the sum of individual measurements.ResultsSignificant differences were observed in the between-subgroup comparisons (Kruskal–Wallis test) of the MPI (3 months, p = 0.01; 6 months, p = 0.04) and linear deviation from intercuspal position (anterior–posterior: 6 months, p = 0.01; inferior–superior: 3 months, p = 0.008; 6 months, p = 0.02). The patients with severe RRR in the FBBA group showed a significant decrease in the MPI and increase in linear inferior deviation from intercuspal position at 3 months (post hoc comparison) as well as a significant increase in the linear posterior and inferior deviation from intercuspal position at 6 months.ConclusionsLO is the preferable occlusal scheme for patients with severe RRR. (This trial has been registered at http://clinicaltrials.gov/ct2/show/NCT00959530.)     

Vertical and horizontal polymerization shrinkage in composite restorations

ObjectivePolymerization shrinkage developed in vertical and horizontal directions after light activation of light-curing composite restorative materials. The purpose of this study was to examine the effects of vertical and horizontal polymerization shrinkage on: (a) dimensional changes of resin composites in tooth cavities; (b) shear bond strengths to enamel and dentin; and (c) marginal gap width in a non-reacting Teflon mold.MethodsVertical and horizontal polymerization shrinkage in tooth cavities were measured immediately (3 min) after light activation. With the same time lapse, shear bond strengths to enamel and dentin and marginal gap widths in Teflon mold were also measured.ResultsThere was a significant correlation between vertical and horizontal polymerization shrinkage (r = 0.647, p = 0.043) in the tooth cavity. Composite materials which produced small vertical shrinkage also produced smaller horizontal shrinkage. Composite materials which produced small vertical shrinkage in the tooth cavity exhibited greater shear bond strengths to both enamel (r = −0.697, p = 0.025) and dentin (r = −0.752, p = 0.012). Composite materials which produced smaller horizontal shrinkage produced smaller marginal gap widths in the Teflon mold (r = 0.829, p = 0.003). No relationships were observed between horizontal shrinkage in the tooth cavity and shear bond strengths to both enamel and dentin (p > 0.05).SignificanceDuring the early stage of setting (<3 min) in tooth cavities, the vertical shrinkage of light-activated composite restorative materials was correlated with horizontal shrinkage.     

Retention and stress distribution in distal extension removable partial dentures with and without implant association

PurposeThe present study aimed to evaluate the retention and stress distribution of conventional (C) RPD and compare to RPD associated to implant for support (IS) and retention (IR).MethodsFrameworks were cast from cp Ti (n = 18) and Co–Cr alloy (n = 18) by plasma and injected by vacuum–pressure. Conventional RPDs were compared to implant associated RPDs using a distal implant to support (IS) or to support and retain (IR) RPD. The specimens were subjected to insertion/removal cycles simulating 5 years of use and the retention force (N) was measured or evaluated. A mixed linear model was used to analyze the data (α = 0.05). Photoelastic models were qualitatively examined for stress when an occlusal load of 15 kgf was applied over support teeth and RPD.ResultsRetention force of IR RPDs is greater than IS and C RPDs for both cp Ti and Co–Cr alloy specimens. Retention force of cp Ti RPDs increased initially and was maintained throughout 5 years of simulation test while Co–Cr RPDs presented a decrease at the beginning of the test and had their retention force maintained throughout the test. Implant placement at residual alveolar ridge decreased stress around teeth, mainly in the first premolar. Stress concentration in the IS RPD is slightly greater than in the IR RPD.ConclusionThe results suggest that implant placement at the distal extension improves retention and stress distribution of RPDs.