Single nucleotide polymorphisms in long noncoding RNA, ANRIL, are not associated with severe periodontitis but with adverse cardiovascular events among patients with cardiovascular disease.

BACKGROUND AND OBJECTIVE: Biological plausibility of an association between severe periodontitis and cardiovascular disease (CVD) has been proven. Genetic characteristics play an important role in both complex inflammatory diseases. Polymorphisms (single nucleotide polymorphisms [SNPs]) in the long noncoding RNA, antisense noncoding RNA in the INK4 locus (ANRIL), were shown to play a leading role in both diseases. The primary objectives of the study were to assess, among cardiovascular (CV angiographically proven ≥50% stenosis of a main coronary artery) patients, the impact of ANRIL SNPs rs133049 and rs3217992 on the severity of periodontitis and the previous history of coronary events, as well as on the occurrence of further adverse CV events. MATERIAL AND METHODS: The prevalence of severe periodontitis was analyzed in 1002 CV patients. ANRIL SNPs rs133049 and rs3217992 were genotyped. The prognostic value of both ANRIL SNPs for combined CV endpoint (stroke/transient ischemic attack [TIA], myocardial infarction, death from a CV-related event, death from stroke) was evaluated after a 3-year follow-up period. Hazard ratios (HRs) were adjusted for established CV risk factors applying Cox regression. RESULTS: ANRIL SNPs rs133049 and rs3217992 were not associated with severe periodontitis or history of CVD in CV patients. In the Kaplan-Meier survival curve including the log rank-test (P = .036) and Cox regression (hazard ratio = 1.684, P = .009) the AA genotype of rs3217992 was shown to be an independent predictor for adverse CV events after 3 years of follow-up. CONCLUSION: SNPs in ANRIL are not risk modulators for severe periodontitis and history of CVD in CV patients. The AA genotype of ANRIL SNPs rs3217992 possesses prognostic power for further CV events within 3 years of follow-up.

Use of floss/interdental brushes is associated with lower risk for new cardiovascular events among patients with coronary heart disease.

BACKGROUND AND OBJECTIVE: Periodontitis has been found to be associated with coronary heart disease (CHD) and stroke. However, only little is known about whether periodontitis and associated confounders are associated with new cardiovascular events among patients with CHD. MATERIAL AND METHODS: A total of 942 inpatients with CHD were examined regarding periodontitis, oral care habits, bacteria in the subgingival biofilm and the expression of interleukin-(IL)-6 c. (coding DNA)-174 genotypes (rs 1800793) to determine whether these confounders are associated with new cardiovascular events within a 1-year follow-up period. Adjusted hazard ratios (HR) with respect of age, gender, smoking, body mass index, use of aids for interdental hygiene, plaque index, occurrence of severe periodontitis and further internal diseases such as diabetes, hypertension, dyslipoproteinemia, number of missing teeth, serological parameters and IL-6 genotypes were generated with Cox regression. RESULTS: In all, 941 cardiovascular patients completed the 1-year follow up and 7.3% of the patients achieved the primary endpoint (myocardial infarction: 2.1%, stroke/transient ischemic attack: 1.8%, cardiovascular deaths: 3.4%). Patients who reported practicing interdental cleaning were younger, less likely to be male or to have severe periodontitis, had a reduced tobacco exposure, had fewer missing teeth, less indices for plaque and bleeding on probing and a significant decreased adjusted risk for new cardiovascular events (HR = 0.2, CI 0.06-0.6, p = 0.01) than those patients with CHD who did not report practicing interdental cleaning. We did not obtain significant increased HR for patients with severe periodontitis (HR = 1.2, CI 0.7-2.1, p = 0.53), carriers of the IL-6 genotypes GC or CC (HR = 1.4, CI 0.8-2.5, p = 0.24) and did not find a significant association between the number of detected various oral species and the incidence of the combined endpoint (HR = 0.9, CI 0.8-1.01, p = 0.07). CONCLUSIONS: These findings suggest that flossing and brushing of interdental spaces might reduce the risk for new cardiovascular events among patients with CHD. The hypothesis that interdental cleaning per se reduces the risk of new cardiovascular events should be examined in an interventional study.

The del/del genotype of the nuclear factor-kappaB -94ATTG polymorphism and its relation to aggressive periodontitis.

BACKGROUND AND OBJECTIVE: Periodontitis is influenced by specific host-dependent immune responses. Periodontopathogens induce innate immune responses, amongst others, via toll-like receptor 2 (TLR2), resulting in activation of the nuclear transcription factor nuclear factor-kappaB (NF-kappaB). The aim of this case-control study was to evaluate links between genetic variants of these genes and chronic/aggressive periodontitis in a multivariate model. MATERIAL AND METHODS: A total of 141 patients with periodontitis (63 with chronic periodontitis and 78 with aggressive periodontitis) and 81 controls without periodontitis were included in the study. Polymorphisms in TLR2 (Arg677Trp, Arg753Gln) and in NF-kappaB (-94ins/delATTG) were determined by restriction fragment length polymorphism and fragment length analyses, respectively. Subgingival bacterial colonization was evaluated using a PCR/DNA probe test (micro-Ident). RESULTS: Although there was no association of the TLR2 polymorphism Arg753Gln with periodontitis, heterozygous carriers (Arg/Gln) were at a higher risk for colonization with bacteria of the 'red complex' (corrected p-value = 0.042). The del/del genotype of the NF-kappaB polymorphism was associated with aggressive periodontitis considering age, gender, smoking and approximal plaque index as potential confounders (odds ratio = 2.81, p = 0.035, 95% confidence interval: 1.08-7.33). del/del carriers had a higher risk for subgingival colonization with Aggregatibacter actinomycetemcomitans (odds ratio = 2.36, p = 0.030, 95% confidence interval: 1.09-5.1; adjusted for age, gender, smoking and pocket depth(bacteria)). CONCLUSIONS: The del/del genotype of NF-kappaB was shown to be associated with the occurrence of aggressive periodontitis.

Interleukin-2 -330 and 166 gene polymorphisms in relation to aggressive or chronic periodontitis and the presence of periodontopathic bacteria.

BACKGROUND AND OBJECTIVE: As a pro-inflammatory cytokine, interleukin-2 mediates the activation, growth and differentiation of T and B lymphocytes and natural killer cells. Promoter polymorphisms of the interleukin-2 gene have been associated with altered interleukin-2 production or identified as prognostic markers for various infectious diseases. Therefore, the aim of this study was to evaluate two polymorphisms at positions -330 T/G and 166 G/T in patients with generalized chronic periodontitis (n = 58) or generalized aggressive periodontitis (n = 73) in comparison with periodontitis-free controls (n = 69). MATERIAL AND METHODS: Both interleukin-2 polymorphisms were analyzed using the polymerase chain reaction with sequence-specific primers. Distributions of single alleles, genotypes and haplotypes were calculated using the chi-square test. Risk factor analyses were carried out by logistic regression with respect to established cofactors for periodontitis. The presence of subgingival bacteria in an individual were analyzed using a molecular biological method (the micro-Ident test). RESULTS: The interleukin-2 genotype -330 TG occurred less frequently in patients with chronic periodontitis (25.9% vs. 49.3%). Moreover, this genotype decreased the adjusted odds ratio for chronic periodontitis (odds ratio = 0.394), whereas the interleukin-2 genotype 166 TT and the haplotype combination interleukin-2 -330,166 TT : TT were associated with an increased adjusted odds ratio (odds ratio = 2.82 or 2.97). For the latter interleukin-2 combination, a positive association for the subgingival presence of Porphyromonas gingivalis (81.3% vs. 59.5%) and bacteria of the 'red complex' (78.1% vs. 56.0%) was shown. CONCLUSION: The interleukin-2 genotypes -330 TG and 166 TT, as well as the combination genotype interleukin-2 TT : TT, could be putative prognostic factors for chronic periodontitis.

Oral health-related quality of life in patients seeking care for dentin hypersensitivity.

The aim of the present study was to evaluate oral health-related quality of life (OHRQoL) impairment in patients seeking care for their hypersensitive teeth in comparison with general population subjects and to investigate the influence of gender and age on OHRQoL in these populations. Study participants were 656 patients without removable prosthodontics who sought treatment for their hypersensitive teeth in German dental offices. These patients were asked to complete the German form of the Oral Health Impact Profile (OHIP-G) prior to treatment. The sum of OHIP-G item responses (OHIP-G49, 0-196) characterized the OHRQoL impairment. Patients' OHIP summary scores were compared with those in a sample of the German general population (n = 1541). The influence of population (patients vs. general population subjects), gender and age was investigated using a multivariable linear regression model. Age presented a curvilinear association with OHRQoL, with lower OHIP scores associated with younger and older adults and higher OHIP scores (indicating impaired OHRQoL) associated with middle-aged adults in both the patient and general populations. Gender influence depended on the population, i.e. female general population subjects had lower OHIP scores than male general population subjects and female patients had higher OHIP scores than male patients. Mean OHIP summary scores indicated that patients with hypersensitive teeth reported considerably more impaired OHRQoL (approximately 22 OHIP units) than subjects in the general population. The present study suggests that the oral condition of hypersensitive teeth is significantly associated with impaired OHRQoL.

Impact of genetic variants of CD14 and TLR4 on subgingival periodontopathogens.

CD14 and toll-like receptor 4 (TLR4) are involved in host's immune response to bacterial pathogens including periodontal bacteria. Functional important gene polymorphisms are described for both genes. The aim of this study was to evaluate links between genetic polymorphisms of CD14 and TLR4 and risk markers of periodontitis in a multivariate model. One hundred and thirty-three periodontitis patients (chronic: n = 60, aggressive: n = 73) and 80 healthy controls without periodontitis were included in the study. Polymorphisms in CD14 c.-159C>T and in TLR4 Asp299Gly, Thr399Ile were determined by restriction fragment length polymorphism analyses. The clinical investigation included smoking status, plaque and bleeding indexes, pocket depth and attachment loss. Subgingival bacterial colonization was analysed molecularbiologically using the micro-Ident test. Prevotella intermedia occurred less frequently in individuals positive for the TT genotype of CD14 in bivariate analysis (odds ratio = 0.36%, confidence interval: 0.14-0.91, P = 0.045). In binary logistic regression analyses, the occurrence of this bacterium was significantly decreased in TT carriers (odds ratio = 0.31%, confidence interval: 0.81-0.12, P = 0.017) considering age, smoking and maximum clinical attachment loss at microbial test site as confounding factors. However, no significant association with chronic and or aggressive periodontitis and polymorphisms in CD14 and TLR4 could be proven. Although the CD14 c.-159C>T polymorphism could be shown to be associated with subgingival colonization with P. intermedia, there is no evidence that CD14 and TLR4 polymorphisms investigated are independent risk factors for chronic or aggressive periodontitis in German periodontitis patients.

The interleukin-10 promoter haplotype ATA is a putative risk factor for aggressive periodontitis.

BACKGROUND AND OBJECTIVE: Interleukin-10 has been described as an anti-inflammatory cytokine and a B-cell proliferation factor. Promoter polymorphisms of the interleukin-10 gene have been associated with altered interleukin-10 expression. Therefore, the aim of this study was to evaluate three polymorphisms at positions -1082G>A, -819C>T and -590C>A in patients with generalized chronic periodontitis (n = 27) and generalized aggressive periodontitis (n = 32) in comparison with periodontitis-free controls (n = 34). MATERIAL AND METHODS: Interleukin-10 promoter polymorphisms were analyzed by polymerase chain reaction with sequence-specific primers (PCR-SSP). Distributions of single alleles, genotypes and haplotypes were calculated by the chi-square test. Risk factor analyses were carried out by logistic regression. Subgingival bacteria were subjected to molecular biological analyses using the micro-Ident test. RESULTS: The combination ATA/ATA was found only in patients with aggressive periodontitis (15.6 vs. 0.0%, p = 0.023). Taking into account age, gender, smoking and plaque level, an increased odds ratio (3.7, p = 0.04) for aggressive periodontitis was shown for subjects with the haplotype ATA. Prevotella intermedia was found to be decreased in ACC- positive (41.3 vs. 66.7%, p = 0.022), ATA-positive (33.3 vs. 57.1%, p = 0.032) and ACC/ATA-positive (20.0 vs. 55.9%, p = 0.002) individuals. In GCC/GCC-positive subjects, P. intermedia occurred more frequently (86.7 vs. 42.3%, p = 0.002). CONCLUSION: The haplotype ATA, which is known as a 'low interleukin-10 producer' is a putative risk indicator for generalized aggressive periodontitis.

Clinical performance of a self-etching and a total-etch adhesive system - 2-year results.

The purpose of this controlled prospective clinical study was to compare the clinical performance of the self-etching adhesive system AdheSE and the established total-etch adhesive system Excite in classes I and II cavities for a period of 2 years. Fifty patients participated in this study. Each received two restorations, one with AdheSE, one with Excite by one calibrated, non-blinded operator. The resin composite used to restore the teeth was Tetric Ceram HB. One calibrated, blinded clinician re-evaluated the restorations at baseline, after 6, 12 and 24 months after placement using the modified Ryge criteria. For this, vitality, post-operative sensitivity, visible marginal irregularity, marginal discolouration, secondary caries, surface texture, anatomic form and filling defect were considered. After 2 years, 67 restorations were reviewed in 34 patients. None of the teeth showed signs of secondary caries. Two teeth, one of each group, had to receive endodontic treatment because of pulp inflammation. All other teeth remained vital. Slight marginal discolourations were observed in six AdheSE restorations and three Excite restorations. These restorations were scored as Beta. After 2 years, an overall clinical success rate, summing up all the Alpha and Beta scores, of 97% was found, viewing both adhesive systems together. Statistic analysis using log-rank test showed no statistic differences in the overall survival rate between the two materials tested within the observation period. It can be concluded that both adhesive systems tested demonstrated very good clinical performance in the restoration of classes I and II cavities at the end of 2 years.

Comparison of the bond strength of selected adhesive dental systems to cortical bone under in vitro conditions.

The study was performed to compare the tensile bond strength attained between composite and bone and between bone and bone using two different adhesive systems (Clearfil New Bond and Histoacryl) in vitro. Sixty porcine bone specimens with a total thickness of 4.0 mm (+/- 0.5 mm) and a cortical layer of 1.5 mm (+/- 0.2 mm) were obtained under standardised conditions. Ten specimens each were assigned to four experimental groups: group A: Clearfil New Bond (bone-composite); group B: Clearfil New Bond (bone-bone); group C: Histoacryl (bone-composite); group D: Histoacryl (bone-bone). The tensile bond strength of the adhesive agents mentioned above was measured 15 min after application and also after light-curing of the composite filling material (Tetric Ceram, colour A2; groups A and C) using a universal testing machine. The tensile bond strength measured was as follows: group A 8.00 MPa (+/- 1.36 MPa), group B 6.39 MPa (+/- 2.05 MPa), group C 5.22 MPa (+/- 1.96 MPa), and group D 1.95 MPa (+/- 0.49 MPa). Tensile bond strength was significantly increased in group A compared to groups C and D (P < 0.05, Tukey's test). The values in group D were significantly reduced compared to all other groups (P < 0.05, Tukey's test). Despite the limitations of an in vitro investigation, it can be concluded that adhesive systems might be a useful alternative in bone bonding. The use of dentin adhesives seemed to produce higher bond strength to bone than that attained with the cyanoacrylate adhesive.

Gender differences in HLA phenotype frequencies found in German patients with generalized aggressive periodontitis and chronic periodontitis.

HLA antigens have been considered as risk factors for periodontitis. Differences in prevalence and in the extent of attachment loss between males and females have suggested that gender-dependent HLA deviations could play a role in individual predisposition to periodontitis. The aim of the present study was therefore to investigate the incidence of gender-dependent HLA associations in 50 patients with generalized aggressive periodontitis (AP) and 102 patients with chronic periodontitis (CP) in comparison to 102 probands without any attachment loss caused by periodontitis. HLA typing was carried out using a microlymphocytotoxic test and a polymerase chain reaction with sequence-specific primers (PCR-SSP). Female AP patients showed an increase in the frequency of HLA-A*68/69 and a decrease in the frequency of DRBblank* (non-DRB3/4/5*) and DQB1*05-positive probands. Only in female CP patients was HLA-DQB1*0303 absent, whereas HLA-DQB1*06 homozygosity increased significantly. With regard to the (AP + CP) periodontitis group as a whole, the increased frequency of HLA-DQB1*06 homozygosity in females was similar to the findings obtained in the AP group. Evidently, gender is a confounding variable, which should be considered in further studies of HLA and periodontitis.

HLA-A, B, Cw, DRB1, DRB3/4/5, DQB1 in German patients suffering from rapidly progressive periodontitis (RPP) and adult periodontitis (AP).

BACKGROUND/AIM: There is growing indication that differences in host response determine susceptibility and resistance to periodontal disease. Particularly, the effect of histocompatibility antigens (HLA) on early onset periodontitis (EOP) has been studied. As most of the results are not conclusive and to date no report has been done on German patients, the aim of this study was to investigate the distribution of HLA alleles in a group of 50 German RPP patients and 102 German AP patients and to compare them to 102 control probands without periodontitis. METHODS: Diagnosis was established according to standardised clinical criteria. HLA typing was performed using serologic and molecular biologic (PCR-SSP) techniques. RESULTS: Compared to the controls, RPP patients had a significantly higher frequency of HLA-DRB1*13 and a significantly lower frequency of HLA-DRBblank*(non-DRB3/4/5). AP patients showed a significantly increased occurrence of HLA-B*14 and -Cw*08 as well as a significantly decreased frequency of HLA-A*03. In both patient groups HLA-A*11 and -A*29 had an increased frequency and HLA-A*31 and -A*30/31 were decreased. These differences were statistical significant in the whole patient group (RPP + AP). CONCLUSIONS: Based on modern DNA techniques the present study shows an association of HLA to both RPP and AP. Certain HLA alleles seem to be associated with susceptibility or resistance to periodontitis in general. However, before this knowledge can be used for differential diagnosis or prognosis, further investigations are necessary.

Tensile bond strengths of four different dentin adhesives on irradiated and non-irradiated human dentin in vitro.

This study evaluated the influence of irradiation on dentin bond strength. Sixty irradiated and 60 non-irradiated human third molars were used. The irradiation dose of 60 Gy was fractionally applied over 6 weeks (2 Gy day(-1), 5 days week(-1). All teeth were prepared in a special manner allowing the simulation of intra-pulpal pressure and dentin perfusion. Dentin specimens with a thickness of 2.0 mm were obtained under standardized conditions. The specimens were randomly assigned to four experimental groups. Tensile bond strength of four different dentin bonding agents (Scotchbond 1, Solobond Plus, Prime&Bond 2.1 and Syntac) was evaluated using an Instron Universal testing machine. Pairwise comparison did not show any significant differences between the irradiated and non-irradiated groups. The influence of the different dentin adhesives was significant (P=0.0001; ANOVA). Compared with Solobond Plus and Prime&Bond 2.1, the use of Scotchbond 1 resulted in a significantly higher tensile bond strength in non-irradiated specimen (P< 0.05; closed test procedure based on Kruskal-Wallis test). Within the limitations of an in vitro study, it can be concluded that adhesive restoration procedures can be successfully used in patients irradiated for cancer of the head and neck.

Influence of two dentin bonding systems on the demineralization of the root surface.

It has been assumed that dentin adhesives can prevent root surface caries. The aim of this study was to determine the caries-protective effect of two different dentin bonding systems on the demineralization of root surfaces in vitro. The root surfaces of 60 freshly extracted caries-free human molars were thoroughly cleaned and polished, thereby removing the cementum. The teeth were then coated with acid-resistant nail varnish, exposing two rectangular windows of 6 mm2 each. One window served as an untreated control, while the other window was treated with a dentin bonding system. The specimens were distributed among the following experimental groups--Group 1: Syntac, Heliobond (no air thinning); Group 2: Syntac, Heliobond (as recommended); Group 3: Syntac, without Heliobond; Group 4: Prime & Bond 2.0 (no air drying); Group 5: Prime & Bond 2.0 (as recommended); Group 6: Prime & Bond 2.0 (dentin pretreated with 36% phosphoric acid). Subsequently, all specimens were demineralized for 6 days with acidified gel (HEC, pH 4.8, 37 degrees C). From each tooth, three dentinal slabs were cut perpendicular to the polished surface of the windows. The slabs were ground to a thickness of 80 microns and imbibed with water. The depth of the respective demineralized areas was determined using a polarized light microscope. All control specimens exhibited lesions with a mean depth of 67 microns. In Groups 2, 3, and 5 the lesion depth was reduced significantly, while in Groups 1, 4, and 6 no lesions could be detected. It was concluded that the demineralization of the root surface can be impeded by application of the dentin adhesives tested.

Root lesions in a group of 50-60 year-old Germans related to clinical and social factors.

From a preventive point of view collection of data concerning carious and non-carious cervical tooth defects is definitely important. Consequently, the prevalence and distribution of different root lesions were studied and correlated with behavioral and biological factors in 50- to 60-year-old German individuals (n = 298). Additionally, the data were correlated with characteristics concerning oral health and known risk factors such as gender, educational level, and presence of plaque. An interview included questions on sociodemographic and socioeconomic characteristics, dental and general health status, and various behavioral parameters. During clinical examination data concerning coronal and root lesions, restorations, probing depth, gingival bleeding, and dental plaque were obtained. The participants represented a social middle class population with a high awareness of dental health. Obviously, for the participants, known risk factors for root decay such as gender, educational level and plaque index were of minor importance. Factors correlating with root caries were: (a) number of missing teeth, (b) probing depth, (c) smoking habit, (d) regular dental attendance and (e) the reason for the last dental treatment. Additionally, the prevalence of non cariogenic lesions, primarily resulting from increased but wrongly performed oral self care, seems gradually to relieve carious root destruction.

Marginal leakage in class II-restorations after use of ceramic-inserts luted with different materials.

The efficiency of using prefabricated ceramic inlays to prevent microleakage has been discussed in different investigations. The purpose of this study was to evaluate the marginal microleakage of a new glass ceramic inlay system in combination with two different composite luting materials and one polyacid-modified composite, respectively. Standardized class II cavities (n = 60) were filled with (1) Empress inlays fixed with a highly viscous luting composite as a control group, and with glass ceramic inlays (Cerana) in combination with (2) a highly viscous luting composite, (3) a low-viscous luting composite and (4) a polyacid-modified composite, respectively. After thermocycling the marginal quality was analysed with scanning electron microscopy, and the dye penetration along the cavity walls was measured. The use of the Cerana inlays with a polyacid-modified composite resin did not reveal a good marginal adaptation. However, the combination of the Cerana and the Empress inlays with the highly viscous composite exhibited a comparable marginal fit. Within the limitations of an in vitro study it is concluded that the combination of the new glass ceramic inlays with a polyacid-modified composite cannot be recommended for clinical use.

Permeability of dentine after Nd:YAG laser treatment: an in vitro study.

The purpose of this investigation was to determine the effects of Nd:YAG laser treatment on the permeability of dentine. Forty dentine discs were prepared by horizontal sectioning through the middle coronal third of freshly extracted non-carious third molars. After the removal of the pulp the discs were finished with 600 grit and divided into three test groups and one control group (n = 10). For the test group three different laser power settings were chosen: test group A: 3 x 60 sec, 60 mJ; test group B: 3 x 60 sec, 90 mJ; test group C: 3 x 60 sec, 120 mJ. No laser treatment was performed on the control group. In a two-chamber system the filtration rate of dentine tubules from an exactly defined area of the specimens was measured using a radioactive Ringer solution under a pressure of 30 cm H2O. Permeability measurements were carried out three times prior to lasing, three times immediately following laser treatment and six times after the application of phosphoric acid. Analysis of variance showed a significant influence of the Nd:YAG laser treatment on the permeability of dentine (P < 0.001). The mean quotient of non-treated control vs. lased dentine was 2.19 +/- 0.86 for the 60 mJ beam, 1.49 +/- 0.88 for the 90 mJ beam, and 2.04 +/- 2.17 for the 120 mJ beam. Etching the lased surfaces had a statistically significant influence on the permeability of the dentine only in the 60 mJ group (P < 0.001). The data show that the Nd:YAG laser treatment often increases the permeability of smear layer covered dentine but moderates the increase of permeability after etching the surface with phosphoric acid.

Correlation of microhardness and wear in differently eroded bovine dental enamel.

The purpose of the study was to compare the microhardness data of differently eroded enamel surfaces with the wear caused by toothbrushing. Sixty bovine enamel specimens were polished and prepared for microhardness determination. The polished surfaces were covered with tape except for a 1.3 x 10.0 mm window. Fifteen specimens each were stored in an erosive beverage (Sprite Light) for either 1, 5 or 15 min. Each specimen was immersed in 10 ml of the beverage. The remaining 15 specimens were not eroded. Interferometrical analysis revealed that substance loss after 15 min of erosion was negligibly low (about 75 mm). In all specimens Vickers microhardness determinations were conducted on eroded (= final hardness) and non-eroded (= initial hardness) enamel surfaces. The specimens were subsequently submitted to toothbrushing abrasion using a slurry consisting of 1 g non-fluoridated dentifrice in 5 ml artificial saliva. The total amount of tooth wear due to erosion and subsequent abrasion was profilometrically evaluated. Statistical analysis revealed a significant decrease in hardness and a significant increase in wear with increasing time of storage in the erosive beverage. Overall regression analysis yielded a statistically significant correlation between both initial and final hardness and the amount of tooth wear. The correlation of abrasion and final hardness could be described by a quadratic mathematical function. It is concluded that the susceptibility of eroded enamel to toothbrushing abrasion can be correlated with Vickers microhardness values, thereby suggesting an overproportionate increase of abrasion with decreasing hardness values.

Fluoride uptake in dentin with and without simulating dentinal fluid flow.

The aim of the present study was to compare fluoride uptake of dentin with and without simulating dentinal fluid flow. Eighty-five dentinal discs were prepared from retained human molars. Seventeen discs were used to assess baseline fluoride content (controls). Sixty-eight discs were evenly distributed among two experimental groups and were fixed for 24 h in a two-chamber device allowing for simulating dentinal fluid flow. Thirty-four samples were treated with dentifrice slurry containing a low fluoride concentration (Elmex, dilution 1:5); the remaining discs were treated with a solution of a high fluoride concentration (Elmex Fluid). For the perfused group, each of the 17 discs of the high and low concentration fluoride groups were constantly perfused during the experiment. The remaining fluoridated specimens were not perfused. All specimens were assayed for KOH-soluble fluoride and structurally bound fluoride. Structurally bound fluoride was determined in three successive layers of 20 microns each. Uptake of KOH-soluble fluoride was significantly higher in the specimens fluoridated with Elmex Fluid compared to the samples treated with the dentifrice slurry. The uptake of KOH-soluble fluoride was not influenced by perfusion of the dentinal discs. However, perfusion resulted in lower acquisition of structurally bound fluoride in the samples treated with the dentifrice slurry. After application of Elmex Fluid, no significant difference was found in the amount of structurally bound fluoride between the perfused specimens and non-perfused samples. It is suggested that further studies on fluoride uptake in dentin should use a model simulating outward dentinal fluid flow.

Clinical comparison of postoperative sensitivity for a glass ionomer and a zinc phosphate luting cement.

In 60 patients, 120 partial and full-coverage restorations were cemented on vital abutment teeth with either a glass ionomer or a zinc phosphate luting cement. A split-mouth design and a patient blind data acquisition protocol were used. During an average observation period of 17.3 months there were no differences between the two types of luting cements in regard to subjective and clinical parameters. A high incidence of postoperative hypersensitivity, which is often said to accompany the use of glass ionomer luting cements, was not observed. With the cementation method used in this study, the glass ionomer cement Ketac-Cem Maxicap was an acceptable alternative to conventional zinc phosphate cement. Capsule systems make the clinical handling of glass ionomer luting cements safe and easy and should be used routinely in dental practice.

Endodontic therapy in a postirradiated child: review of the literature and report of a case.

Exodontia of extremely carious teeth leads to a significant risk of osteoradionecrosis in patients who have undergone radiotherapy. In these patients, endodontic treatment could be an alternative. Successful root canal therapy in a girl who had been irradiated for head and neck neoplasms is reported. The results indicated that use of calcium hydroxide to obturate the root canals is a viable method of postirradiation endodontics in primary teeth.