Runs of homozygosity are associated with staging of periodontitis in isolated populations.

Periodontitis is a common inflammatory disease characterized by a complex etiology, which is the result of a combination of genetic and environmental factors. Genetic variants linked to the periodontitis disease were already investigated, however, little was known regarding the severity of this disease. Recently, long runs of homozygosity (ROH) were associated with several multifactorial diseases. Therefore, in our work, we tried to assess the role of ROH and periodontitis status. We found an association between the excess of homozygosity owing to ROH and staging of periodontitis. More in detail, the total amount of homozygosity owing to ROH is positively associated with an increased severity of periodontitis (P = 0.0001). Regression tree analysis showed the impact of ROH burden in discriminating individuals with mild periodontitis stages I and II and periodontitis stages III and IV (P < 0.001). Furthermore, ROH mapping highlights several regions associated with a severe status of periodontitis (odds ratio > 1). Among them, we found a total of 33 genes. Interestingly, some of these genes were previously associated with granulocyte or platelet measures, both linked to the onset and the progression of periodontal disease. Our results suggest the not only single variants association test could help to risk assessment but even individual genomic features; furthermore, our ROH mapping highlighted the possible role of multiple genes in periodontal development.

Effects of Finish Line Design and Fatigue Cyclic Loading on Phase Transformation of Zirconia Dental Ceramics: A Qualitative Micro-Raman Spectroscopic Analysis.

OBJECTIVES: Stresses produced during the fabrication of copings and by chewing activity can induce a tetragonal-to-monoclinic (t⁻m) transformation of zirconia. As a consequence, in the m-phase, the material is not able to hinder possible cracks by the favorable mechanism known as "transformation toughening". This study aimed at evaluating if different marginal preparations of zirconia copings can cause a premature phase transformation immediately after manufacturing milling and after chewing simulation. METHODS: Ninety copings using three commercial zirconia ceramics (Nobel Procera Zirconia, Nobel Biocare Management AG; Lava Classic, 3M ESPE; Lava Plus, 3M ESPE) were prepared with deep-chamfer, slight-chamfer, or feather-edge finish lines (n = 10). Specimens were tested in a chewing simulator (CS-4.4, SD Mechatronik) under cyclic occlusal loads simulating one year of clinical service. Raman spectra were acquired and analyzed for each specimen along the finish lines and at the top of each coping before and after chewing simulation, respectively. RESULTS: Raman analysis did not show any t⁻m transformation both before and after chewing simulation, as the typical monoclinic bands at 181 cm-1 and 192 cm-1 were not detected in any of the tested specimens. CONCLUSIONS: After a one-year simulation of chewing activity, irrespective of preparation geometry, zirconia copings did not show any sign of t⁻m transformation, either in the load application areas or at the margins. Consequently, manufacturing milling even in thin thickness did not cause any structural modification of zirconia ceramics "as received by manufacturers" both before and after chewing simulation.

Long-term bond strength and endogenous enzymatic activity of a chlorhexidine-containing commercially available adhesive.

OBJECTIVES: The aim of this study was to investigate, by the means of microtensile bond strength (µTBS) test, gelatin and in situ zymography, the influence of 0.2% CHX contained within a commercially available adhesive on long-term bond strength and endogenous enzymatic activity. METHODS: Non-carious teeth were subjected to µTBS test (N = 15 for each group) and stressed until failure. µTBS was evaluated immediately and after 12-month storage in artificial saliva at 37 °C. Dentin powder was obtained from additional teeth (N = 7) for gelatin zymography, while for in situ zymography, 3 teeth for each group were selected. Gelatin and in situ zymography were performed in dentin powder and slices of dentin, respectively, to assess the ability of 0.2% CHX blended within the adhesive to inhibit endogenous enzymatic activity. RESULTS: µTBS bond strength was higher in the CHX-containing groups, immediately as well as after aging. The bond strength significantly decreased after 12-month aging. The activation of endogenous MMPs was found to be related to the presence of CHX within the adhesive system and the bonding strategy employed. CONCLUSIONS: Under this perspective 0.2% CHX blended within Peak Universal adhesive monomer seems to increase immediate bond strength, to preserve bond strength over time and to efficiently inhibit endogenous enzymatic activity in dentin. Hence, blending the CHX in low concentrations within the adhesive could be recommended as a feasible technique in every-day clinical practice. CLINICAL SIGNIFICANCE: Using CHX-containing adhesives could be recommended due to several benefits: it seems to increase the longevity of the hybrid layer; the inhibitor appears to be efficiently delivered to the dentinal substrate and to inhibit endogenous enzymatic activity, without prolonging chair time.

Association of LTA gene haploblock with periodontal disease in Italian adults.

BACKGROUND: Periodontitis is a common oral disease caused by host inflammatory response towards bacteria biofilm. The chronic activation of immune response leads to destruction of teeth supporting tissue, bone loss and tooth detachment. Different factors could be involved in the development and severity of the disease; among them the host genetic background should be considered. OBJECTIVES: In our study, we analysed haploblocks in a genomic region within major histocompatibility complex (MHC) locus aimed at disclosing a possible correlation with the risk of periodontal disease in 602 adult subjects from North-East Italy. RESULTS: The CTTAC haploblock (formed by LTA-rs2857709, LTA-rs2844484, LTA- rs2229094, LTA-rs2229092 and LTA-rs1041981 polymorphisms) correlated with protection towards periodontitis condition, after regression analysis including age and smoking status as covariates (P-value = 0.015). CONCLUSION: Our results suggest that a haplotype within LTA gene (encoding for lymphotoxin alpha) is involved in the susceptibility towards chronic periodontitis.

Intraoperative Complications During Sinus Floor Elevation with Lateral Approach: A Systematic Review.

PURPOSE: To analyze the occurrence of intraoperative complications during sinus floor elevation with a lateral approach and their correlations with the technique adopted by surgeons. MATERIALS AND METHODS: Electronic and manual searches resulted in 4,417 records on sinus floor elevation. Twenty-one randomized clinical trials (RCTs) and 11 prospective controlled clinical trials (CCTs) reporting occurrence of intraoperative complications were included. Risk of bias was assessed according to the Cochrane tool and a modified Downs and Black quality analysis for RCTs and CCTs, respectively. RESULTS: Sinus membrane perforation and hemorrhagic events following vascular lesions were the only intraoperative complications reported by the selected studies with overall occurrences of 15.7% and 0.4%, respectively. Three different surgical devices (rotary instruments, piezoelectric osteotomes, and manual bone scrapers) were used to perform the lateral antrostomy. Ultrasonic devices and bone scrapers showed a lower incidence (10.9% and 6.0%, respectively) of membrane perforation compared with that of rotary instruments (20.1%). Among the different ultrasonic procedures, erosion of the lateral antral wall showed the lowest membrane perforations (4.7% incidence). Hemorrhagic complications seemed to be extremely infrequent with any surgical technique. CONCLUSION: Sinus membrane perforation was the most frequently described intraoperative complication during sinus floor elevation with a lateral approach. Thinning the lateral wall of the sinus before performing the antrostomy (either with ultrasonic devices or manual bone scrapers) seemed to be an important factor in preventing membrane perforation during sinus surgery. Further high-quality RCTs specifically investigating intraoperative complication occurrence are needed.

NLRC5 polymorphism is associated with susceptibility to chronic periodontitis.

Periodontitis is a chronic oral pathology caused by impaired immune response against oral bacteria resulting in tissue inflammation and damage. Among the members of innate immune response, the first line of defence against pathogens, inflammasomes are macro-molecular protein complexes that can be activated by different stimuli, comprised bacteria infections. Different proteins are involved in inflammasoma formation; the most important are molecules belonging from the family of nucleotide-binding and oligomerization domain (NOD)-like receptors (NLRs). In this study, polymorphisms within 20 NLRs related genes were analysed in order to investigate their possible association with periodontitis susceptibility in a population from North-East Italy. One polymorphism, namely rs289723, in NLRC5 gene resulted associated with chronic slight and chronic localized periodontitis susceptibility, specifically A/A genotype was correlated with increased risk of disease development. Our study, for the first time, identified the possible involvement of a polymorphism within NLRC5 gene as a possible biomarker for periodontitis condition susceptibility among Italian individuals from genetic isolates.

Micromorphometric analysis of bone blocks harvested with eight different ultrasonic and sonic devices for osseous surgery.

OBJECTIVES: The aim of this study was to analyse in vitro the main features of osteotomies performed by means of different ultrasonic and sonic systems for bone surgery. MATERIALS AND METHODS: Six ultrasonic and two sonic devices for osseous surgery were evaluated during block harvesting on bovine bone. After measuring cutting speed, images of the blocks were acquired by light stereo-microscope and E-SEM, in order to measure the osteotomy thickness and to evaluate the presence of intra-trabecular bone debris and signs of thermal injuries on the bone. Roughness evaluation was performed using a profilometer. RESULTS: All the ultrasonic instruments required a shorter time than sonic systems to perform the block harvesting (p < 0.05). Piezomed was found to be the most efficient in terms of cutting speed (20.5 mm(2)/min), even if not significantly different from most of the devices here tested (p > 0.05). K-Bisonic and Variosurg 3 showed the smallest percentage variance between tip thickness and osteotomy width. Intra-trabecular debris was found to occur in inverse proportion with the width of the osteotomy: the tighter the track, the higher the amount of debris. Sonicflex Bone, Piezotome 2 and Sonosurgery showed almost no signs of thermal injuries on the osteotomised surfaces. CONCLUSIONS: No single ultrasonic or sonic device combined all the best features of speed, precision and bone micro-architecture preservation.

Effect of carboidiimide on thermal denaturation temperature of dentin collagen.

OBJECTIVES: 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) has been shown to cross-link dentin type I collagen. Increased cross-linking usually elevates the glass transition temperature of polymers. The aim of this study was to evaluate the cross-linking reaction promoted by EDC in different aqueous concentrations by measuring the thermal denaturation temperature (Td) of human dentin collagen. METHODS: The Td of dehydrated collagen and of insoluble dentin matrix collagen immersed in 0.5M or 1M EDC aqueous solution for different treatment times was obtained using a Differential Scanning Calorimeter (DSC). Specimens were also analyzed by Energy Dispersive X-Ray Spectroscopy. RESULTS: EDC-treated dentin collagen showed a significantly higher Td than the untreated specimens when immersed in either 0.5M EDC or 1M EDC for 10min or longer (p<0.05). EDC-treated dentin collagen showed an increase of sulfur and chloride, not detectable in EDC-untreated dentin specimens. Conversely, the relative amount of carbon, nitrogen and oxygen was not modified by treatments. SIGNIFICANCE: EDC-treated dentin collagen showed a higher Td than the untreated control at all tested concentrations and immersion times. A higher Td can be considered an indirect indicator of a more resistant and highly cross-linked collagen network. More data are needed to confirm these results.

Polymorphisms in sweet taste genes (TAS1R2 and GLUT2), sweet liking, and dental caries prevalence in an adult Italian population.

The aim of the study was to assess the relationship between sweet taste genes and dental caries prevalence in a large sample of adults. In addition, the association between sweet liking and sugar intake with dental caries was investigated. Caries was measured by the decayed, missing, filled teeth (DMFT) index in 647 Caucasian subjects (285 males and 362 females, aged 18-65 years), coming from six villages in northeastern Italy. Sweet liking was assessed using a 9-point scale, and the mean of the liking given by each individual to specific sweet food and beverages was used to create a sweet liking score. Simple sugar consumption was estimated by a dietary history interview, considering both added sugars and sugar present naturally in foods. Our study confirmed that polymorphisms in TAS1R2 and GLUT2 genes are related to DMFT index. In particular, GG homozygous individuals for rs3935570 in TAS1R2 gene (p value = 0.0117) and GG homozygous individuals for rs1499821 in GLUT2 gene (p value = 0.0273) showed higher DMFT levels compared to both heterozygous and homozygous for the alternative allele. Furthermore, while the relationship sugar intake-DMFT did not achieve statistical significance (p value = 0.075), a significant association was identified between sweet liking and DMFT (p value = 0.004), independent of other variables. Our study showed that sweet taste genetic factors contribute to caries prevalence and highlighted the role of sweet liking as a predictor of caries risk. Therefore, these results may open new perspectives for individual risk identification and implementation of target preventive strategies, such as identifying high-risk patients before caries development.

Effect of ozone application on the immediate shear bond strength and microleakage of dental sealants.

PURPOSE: The purpose of this study was to evaluate whether gaseous ozone application affects the immediate enamel bond strength or microleakage of 2 dental sealants. METHODS: Sixty bovine incisors were randomly divided into 4 groups, and sealants were applied to the enamel surfaces as follows: ozone + Concise; Concise (control); ozone + UltraSeal XT Plus; and UltraSeal XT Plus (control). Ozone application was performed for 80 seconds, and shear bond strength was measured. Additionally, 60 human molars were randomly divided into 4 groups, as aforementioned, and sealants were applied onto occlusal surfaces. Dye penetration (microleakage) was assessed. RESULTS: No significant differences were found between the 2 sealants. Ozone application did not result in a significant reduction in enamel bond strength or an increase in microleakage. CONCLUSIONS: Ozone gas did not compromise the adhesion of tested materials; therefore, one can disinfect the enamel surface before placing a dental sealant without impairing the material's clinical performance.

Degree of conversion of two-step etch-and-rinse adhesives: In situ micro-Raman analysis.

OBJECTIVES: DC of three commercial two-step etch-and-rinse adhesives across the dentine-adhesive interface was investigated using micro-Raman spectroscopy. The hypothesis tested was that no difference in DC would exist among the adhesives tested. METHODS: Adper Scotchbond 1XT (3M ESPE), Prime&Bond NT (Dentsply DeTrey), and Ambar (FGM) were applied on human dentine disks (n=9). Composite increments of 2mm were then applied on the adhesive surface. Raman spectra were collected along the dentine-adhesive interface. The relative intensities of the peaks associated with the mineral (PO(4)(3-) at 960cm(-1)) and the adhesive (CC at 1640cm(-1); phenyl CC at 1610cm(-1)) were used to identify the adhesive within the hybrid layer and calculate its DC. RESULTS: Adper Scotchbond 1XT and Ambar showed similar DC (79±7% and 77±7%, respectively), while a lower DC was found for Prime&Bond NT (70±7%; p<0.05). CONCLUSIONS: The hypothesis tested was rejected because differences were found among the adhesives tested. The difference in DC among the three adhesive systems can be attributed to different monomer compositions and solvents. Further studies are needed to correlate DC with other mechanical properties of these adhesives. CLINICAL SIGNIFICANCE: Insufficient polymerization of an adhesive can result in a weak hybrid layer, and the presence of unreacted monomers may result in degradation of the polymeric network, decreasing the strength and longevity of the bond. In the present study, Adper Scotchbond 1XT and Ambar performed significantly better than Prime&Bond NT.

Influence of post type on degree of conversion of a resin-based luting agent.

PURPOSE: To assess the degree of conversion (DC) at different levels of a resin-based luting agent used with different commercial posts. METHODS: A resin-based luting agent (Variolink II) was light-cured in a simulated dowel space in combination with different fiber posts: GC Fiber Post (GC), DT Light Safety Lock (SL), RelyX Fiber Post (RX), Reforpost (RE), DT Light Post Illusion (LPI), FRC Postec Plus (FP), Radix (RA), Snowpost (SP), Dentin Post X (DP), Macrolock Illusion (MI), and Composipost (CP). After 24 hours, DC was assessed through micro-Raman analysis at the coronal, middle, and apical thirds. Two-way ANOVA and Tukey test were used for post-hoc comparisons (P<0.05). RESULTS: The results demonstrated that the post-type, dowel space level, and between-factor interaction were statistically significant (P<0.001). Differences in DC were observed at different depths for RX, RE, LPI, SL, DP, MI and CP, decreasing from the coronal to the apical third. Although the resin-based luting agent should be able to polymerize in absence of light, a higher DC was found following light irradiation (with a decreasing effect from the coronal to the apical third).

The effect of curing mode on extent of polymerization and microhardness of dual-cured, self-adhesive resin cements.

PURPOSE: To compare the effect of curing mode (self- or light-cure) on the extent of polymerization (%EP1 as measured using differential scanning calorimetry, (DSC) and microhardness of two dual-cured, self-adhesive resin cements, using a conventional, dual-cured resin cement as control. METHODS: Small amounts of the commercial self-adhesive cements Maxcem and RelyX Unicem or Panavia F2.0 dual-cure resin based cement used as control were polymerized within the DSC chamber at 35 degrees C under a nitrogen atmosphere. 10 specimens were light-cured immediately (20 seconds, 600 mW/cm2) and left undisturbed for 2 hours and 10 additional specimens were left to self-cure in the dark for 2 hours. Following DSC treatment, microhardness of the specimens was measured (Vickers). For each test parameter, data were analyzed with a two-way ANOVA and the Tukey post hoc test. RESULTS: %EP and microhardness of all cements were higher when the light-cure mode of dual-activation was used (P<0.05) instead of only self-curing. No significant difference in %EP was found between either self-adhesive cement or the control using either the light- or self-curing modes. In the light-activated mode, the conventional, dual-cure control cement demonstrated lower microhardness than the self-adhesive cements (P<0.05).

An in vivo study of the effect of a 38 percent hydrogen peroxide in-office whitening agent on enamel.

BACKGROUND: In an in vivo study, the authors tested the hypothesis that no difference in enamel surface roughness is detectable either during or after bleaching with a high-concentration in-office whitening agent. METHODS: The authors performed profilometric and scanning electron microscopic (SEM) analyses of epoxy resin replicas of the upper right incisors of 20 participants at baseline (control) and after each bleaching treatment with a 38 percent hydrogen peroxide whitening agent, applied four times, at one-week intervals. The authors used analysis of variance for repeated measures to analyze the data statistically. RESULTS: The profilometric analysis of the enamel surface replicas after the in vivo bleaching protocol showed no significant difference in surface roughness parameters (P > .05) compared with those at baseline, irrespective of the time interval. Results of the correlated SEM analysis showed no relevant alteration on the enamel surface. CONCLUSIONS: Results of this in vivo study support the tested hypothesis that the application of a 38 percent hydrogen peroxide in-office whitening agent does not alter enamel surface roughness, even after multiple applications. CLINICAL IMPLICATIONS: The use of a 38 percent hydrogen peroxide in-office whitening agent induced no roughness alterations of the enamel surface, even after prolonged and repeated applications.