Effect of surface treatment on shear bond strength of zirconia to human dentin.

PURPOSE: The effect of surface treatment using tribochemical silica coating/silane coupling on the shear bond strengths of (1) a glass-infiltrated, zirconia-reinforced alumina (In-Ceram Zirconia) and (2) a yttria-stabilized zirconia ceramic (YZ Zirconia) to human dentin was studied. MATERIALS AND METHODS: Twelve specimens of each ceramic were randomly assigned to one of three surface treatments: (1) no surface treatment (control group); (2) a chairside tribochemical silica coating/silane coupling system (CoJet group); and (3) a laboratory tribochemical silica coating/silane coupling system (Rocatac group). The mode of failure of each specimen was determined under magnification. RESULTS: The shear bond strengths (mean ± SD) of In-Ceram Zirconia of the control, CoJet and Rocatec groups were 5.7 ± 4.3 MPa, 11.4 ± 5.4 MPa, and 6.5 ± 4.8 MPa, respectively. The corresponding figures for YZ Zirconia were 8.2 ± 5.4 MPa, 9.8 ± 5.4 MPa, and 7.8 ± 4.7 MPa. Two-way ANOVA revealed significant differences in bond strength due to the difference in surface treatment (p= 0.02), but the bond strengths between the two ceramics were not significantly different (p= 0.56). Post hoc tests showed that In-Ceram Zirconia treated with CoJet had significantly higher shear bond strengths than those untreated (p < 0.05) or treated with Rocatec (p < 0.05). Surface treatment did not affect the shear bond strength of YZ Zirconia significantly (p > 0.05). CONCLUSION: The bonding of In-Ceram Zirconia can be improved by the chairside surface treatment system.

Oral health status of low-income, middle-aged to elderly Hong Kong Chinese with type 2 diabetes mellitus.

PURPOSE: To study oral health conditions, diabetic medical complications and their association in type 2 diabetes mellitus (DM). MATERIALS AND METHODS: Cross-sectional survey of 364 type 2 DM patients (63.6 +/- 10.1 years, 54% female) and 161 controls (64.1 +/- 10.6 years, 53% female) with or without essential hypertension, predominantly low-income, attending a hospital were recruited. Periodontal disease (Community Periodontal Index [CPI]) and dental status (decayed, missing and filled teeth [DMFT]) were recorded. Fasting plasma glucose and, for DM patients, HbA1C and DM complications were recorded on enrolment and follow up, respectively. RESULTS: Many DM subjects had fair diabetic control. Both groups (control/DM) had poor oral health: DMFT = 14.5/16.8, CPI 4 = 36%/50%, (P < 0.02) while DM subjects had less DT(adjusted) = 2.1/1.4 (P < 0.01). Of the follow-up DM individuals, 294 (81%) had medical complication(s). Regression analyses showed association between advanced periodontal attachment loss (ALoss) and age, male gender, smoking and DM; MT and DMFT were associated with age, female gender, smoking, DM and hypertension. ALoss and DMFT were not associated with DM complications. CONCLUSIONS: The oral health of the surveyed Chinese subjects was poor. Type 2 DM subjects were affected more by ALoss and MT but less DT. Subjects with hypertension had higher odds for MT.

Shear bond strength between nickel-chromium and human dentine using a dual-cure, self-adhesive universal resin luting agent.

The adhesive property of a dual-cure, self-adhesive universal resin luting agent (Rely X Unicem, 3M ESPE) between nickel-chromium (Ni-Cr) and human dentine was compared with three conventional resin luting agents (Calibra, Dentsply; Panavia-F, Kuraray; All-bond 2 C & B cement, Bisco). Ten Ni-Cr rods were bonded to human dentine with each of the four luting agents, and were subjected to shear bond test. Results showed that there was no significant difference in shear bond strengths among the luting agents. A dual-cure, self-adhesive universal resin luting agent was shown to have comparable adhesive property between Ni-Cr and human dentine as three other conventional resin luting agents. Given the simplicity of use of the dual-cure, self-adhesive universal resin luting agent, it appears to be promising in clinical applications.

Identification of cultivable microorganisms from root canals with apical periodontitis following two-visit endodontic treatment with antibiotics/steroid or calcium hydroxide dressings.

The study was aimed at comparing the efficacy of disinfection of root canals with periapical radiolucencies when treated with either antibiotics/steroid medicaments (Ledermix or Septomixine) or a calcium hydroxide paste (Calasept). Microbiological samples were taken before and after two-visit endodontic treatment from 88 canals with apical periodontitis. All of the canals but one (87 of 88) had cultivable growth before treatment. After dressing with Ledermix, Septomixine, or Calasept, the percentages of canals remained with positive growth were 48% (13 of 27), 31% (8 of 26), and 31% (11 of 35), respectively. The chi(2) tests showed there were no significant differences in the number of canals with positive growth or mean colony forming units counts after instrumentation, irrigation and dressing. In the Ledermix group, 38 strains of bacteria were recovered. The Septomixine group had 25 strains, and the Calasept group had 25 strains. Gram-positive facultative anaerobic cocci (including staphylococci and streptococci) were more prevalent than the Gram-negative obligate anaerobic rods after treatment in all three groups. Similarities in the reduced number of canals with residual growth, and the prevalence of Gram-positive facultative anaerobic cocci suggest that the use of different inter-appointment dressings produced similar microbiological outcomes. However, factors other than the antimicrobial effectiveness of intracanal medicaments may also be responsible for the results observed.

Identification of cultivable microorganisms from primary endodontic infections with exposed and unexposed pulp space.

This study was aimed at comparing the cultivable microorganisms in canals with periapical radiolucencies with exposed and unexposed pulp space. Microbiological samples were taken and analyzed from 45 canals with exposed pulp space, and 43 canals with unexposed pulp space. The canal contents were analyzed by aerobic/anaerobic culture, and conventional identification techniques. There were 211 isolates of bacteria belonging to 28 genera and 55 species recovered from exposed canals. In the unexposed group, 185 isolates of bacteria were recovered, of which 54 species of 28 genera were identified. Among the four most common genera, Prevotella was significantly more common in the exposed group (51/211 in the exposed group versus 30/185 in the unexposed group) (p = 0.049), while there were no differences in prevalence of Actinomyces, Peptostreptococcus, and Campylobacter between two groups of canals. In addition, Fusobacterium nucleatum and Propionibacterium acne were significantly more common in the unexposed canals (p = 0.047 and p = 0.0051, respectively). Similarity in bacterial species in these two groups suggests that pulp space exposure may not be a significant factor in determining the type of bacteria present in infected canals.

Clonality of bacterial consortia in root canals and subjacent gingival crevices.

AIM: No oral niche can be considered to be segregated from the subjacent milieu because of the complex community behavior and nature of the oral biofilms. The aim of this study was to address the paucity of information on how these species are clonally related to the subjacent gingival crevice bacteria. METHODS: We utilized a metagenomic approach of amplifying 16S rDNA from genomic DNA, cloning, sequencing and analysis using LIBSHUFF software to assess the genetic homogeneity of the bacterial species from two infected root canals and subjacent gingival crevices. RESULTS: The four niches studied yielded 186 clones representing 54 phylotypes. Clone library comparisons using LIBSHUFF software indicated that each niche was inhabited by a unique flora. Further, 42% of the clones were of hitherto unknown phylotypes indicating the extent of bacterial diversity, especially in infected root canals and subjacent gingival crevices. CONCLUSIONS: We believe data generated through this novel analytical tool shed new light on understanding oral microbial ecosystems.

Direct detection of Actinomyces spp. from infected root canals in a Chinese population: a study using PCR-based, oligonucleotide-DNA hybridization technique.

OBJECTIVES: The poor sensitivity of phenotypic identification techniques has hampered the taxonomic differentiation of Actinomyces. Hence we developed a sensitive and specific, PCR-based oligonucleotide-DNA hybridization technique to detect Actinomyces spp. and, used this method to detect these organisms in samples directly obtained from infected root canals. METHODS: A total of 32 samples from 28 Chinese patients, with primary root canal infections, aseptically exposed at the first patient visit, were studied. Whole bacterial genomic DNA was isolated directly from paper point samples. The variable regions of 16S ribosomal DNA of bacteria were amplified and labeled with digoxigenin for further hybridization and detection. A total of seven oligonucleotide probes specific for A. bovis, A. gerencseriae, A. israelii, A. meyeri, catalase-negative A. naeslundii (genospecies 1 and 2), catalase-positive A. naeslundii genospecies 2 and A. odontolyticus were used. RESULTS: 16 of the 32 teeth were infected with one or more Actinomyces species. The prevalence rates of the examined species were: A. odontolyticus 31.3%, A. meyeri 9.4%, A. naeslundii 9.4%, A. israelii 6.3% and A. gerencseriae 3.1%; no A. bovis was detected in any of the canals. Furthermore, A. odontolyticus was isolated more frequently from root canals with caries or a history of caries (Fisher's exact test: P=0.0496; Odds ratio=9.00, 95% confidence interval: 0.97-83.63), and A. naeslundii was significantly associated with traumatized teeth (Fisher's exact test: P=0.0121; Odds ratio=57.00, 95% confidence interval: 2.10-1546.90). However, no significant correlation was found between Actinomyces spp. and clinical symptoms and signs, such as pain, swelling, percussion to tenderness, sinus and periapical radiolucency. CONCLUSION: Actinomyces spp. may be important pathogens of root canal infections. A. naeslundii in particular may be related with traumatized teeth. A. odontolyticus appears to be involved in infections related to caries, exposure of dentinal tubules during cavity preparation and/or leaking restoration, but further clarification with large samples is necessary.

Clinical evaluation of packable and conventional hybrid resin-based composites for posterior restorations in permanent teeth: results at 12 months.

BACKGROUND: Packable resin-based composites and simplified resin bonding systems are marketed to offer many advantages over conventional posterior hybrid composites and total-etch bonding systems. The authors conducted a study to evaluate the initial clinical performances of a packable and a conventional hybrid resin-based composite used with a simplified bonding system. METHODS: A total of 57 Class I and 45 Class II restorations were placed in the permanent teeth of 65 adult patients. The carious lesions were restored with either packable resin-based composite (SureFil, Dentsply DeTrey GmbH, Konstanz, Germany) or conventional hybrid resin-based composite (SpectrumTPH, Dentsply DeTrey GmbH), using a resin adhesive (Non-Rinse Conditioner and Prime & Bond NT, both manufactured by Dentsply DeTrey GmbH). The authors evaluated the restorations using U.S. Public Health Service-Ryge modified criteria (in which Alfa is the highest rating) and by using color transparencies and die stone replicas. RESULTS: Three SureFil restorations failed before their baseline evaluation. There were no failures among the 78 SpectrumTPH restorations evaluated at 12 months. For both resin-based composites, Alfa ratings were 90 percent or higher for marginal discoloration, anatomical form, surface texture and surface staining. Lower percentages of restorations were rated Alfa for color match, marginal integrity and gingival health. Occasional mild postoperative sensitivity was reported for four SureFil restorations and one SpectrumTPH restoration. The mean occlusal wear rate was 38 micrometers for the larger SureFil restorations and 25 microm for the smaller SpectrumTPH restorations. CONCLUSIONS: The 12-month clinical performances of the two restorative materials were satisfactory and not significantly different for each of the parameters evaluated. CLINICAL IMPLICATIONS: A packable and a conventional hybrid resin-based composite placed with a simplified bonding system in posterior permanent teeth showed satisfactory and similar results after 12 months.

Implant treatment of macroglossia and edentulous mandible following radiotherapy for nasopharyngeal cancer: a case report.

Radiotherapy for the nasopharyngeal cancer patient with poor oral care may lead to severe deterioration of the dentition and may require multiple extractions. Although the use of an implant-retained overdenture can successfully restore the function and esthetics of edentulous patients, its use can be complicated by the tissue changes subsequent to head and neck irradiation. The difficulties in implant treatment planning for an edentulous patient with macroglossia and soft tissue changes following radiotherapy are discussed.

Cough syrup addiction and rampant caries: a report of two cases.

Sugar-containing syrups such as cough medications have been recognised as potentially cariogenic, especially for chronically sick children suffering from otitis media, seizure disorder, congenital cardiac diseases and asthma. Unfortunately, an increasing number of juveniles are addicted to cough syrups containing centrally-acting drugs and these individuals not only end up with medical and social problems, but also with dental manifestations. This paper addresses the latter problem with the help of two illustrative cases.

Rehabilitating a patient with bruxism-associated tooth tissue loss: a literature review and case report.

Tooth tissue loss from bruxism has been demonstrated to be associated with various dental problems such as tooth sensitivity, excessive reduction of clinical crown height, and possible changes of occlusal relationship. A literature search revealed a number of treatment modalities, with an emphasis on prevention and rehabilitation with adhesive techniques. Rehabilitating a patient with bruxism-associated tooth tissue loss to an acceptable standard of oral health is clinically demanding and requires careful diagnosis and proper treatment planning. This article describes the management of excessive tooth tissue loss in a 43-year-old woman with a history of bruxism. The occlusal vertical dimension of the patient was re-established with the use of an acrylic maxillary occlusal splint, followed by resin composite build-up. Full-mouth oral rehabilitation ultimately involved constructing multiple porcelain veneers, adhesive gold onlays, ceramo-metal crowns, and fixed partial dentures.

Restorative management of the worn dentition: I. Aetiology and diagnosis.

In this, the first of a four-part series on the restorative management of the worn dentition, the aetiological factors, diagnosis of toothwear and preventive measures are summarized. Later papers will deal with the management of localized anterior and posterior toothwear, the use of 'Dahl type' appliances as an effective means for the restorations and the various treatment options for the management of the dentition showing generalized wear. The series will discuss the relative merits of the treatment strategies, clinical techniques and dental materials for the restoration of health, function and aesthetics for the dentition.

Restorative management of the worn dentition: 4. Generalized toothwear.

This is the final paper of a four part series on the management of worn dentition. The factors affecting the selection of restorative techniques for generalized toothwear, such as pulpal vitality, jaw relationship and occlusal guidance are discussed. The practical steps of oral rehabilitation using fixed prostheses are illustrated with two clinical cases.

Restorative management of the worn dentition: 3. Localized posterior toothwear.

In the management of localized posterior occlusal toothwear, care must be taken not only in determining whether the worn teeth are restorable, but also the desirable occlusal scheme. Assessments of the periodontal, endodontic, and coronal tooth tissues, and the occlusal relationship are necessary for a comprehensive treatment plan for worn posterior teeth.

Restorative management of the worn dentition: 2. Localized anterior toothwear.

This is the second paper in a four-part series detailing the relative merits of the treatment strategies, clinical techniques and dental materials for the restoration of health, function and aesthetics for the dentition. In this paper the management of wear in the anterior dentition is discussed, using three case studies as illustration.

Diagnostic performance of mandibular bone density measurements in assessing osteoporotic status.

PURPOSE: The study evaluated the diagnostic performance of computed tomography (CT) bone density measurements (in Hounsfield units [HU]) in assessing the osteoporotic status of edentulous subjects (21 men, 40 women) scheduled to receive mandibular implant-supported overdentures. MATERIALS AND METHODS: Density (in HU) of 61 left and 61 right mandibular canine sites was measured. Each subject was also subject to body bone mineral density measurements (dual-energy x-ray absorptiometry). Bone density T-score values of total hip, femoral neck, spine (L1 to L4), and total body were assessed. Pearson correlations were conducted between HU of each mandibular bone site and the subject's T-score values. Sensitivity/specificity and receiver operating characteristic curve analyses were used to assess the diagnostic performance of HU in detecting subjects who were, based on each of the four T-scores: (1) "not osteonormal", ie, with a T-score at or below -1.0; or (2) osteoporotic, ie, with a T-score at or below -2.5. RESULTS: HU measurements of mandibular bone sites were found to have modest but significant correlations with each bone density T-score value (total hip, femoral neck, spine, total body). CT mandibular site HU measurement has diagnostic value in detecting a "not osteonormal" condition when total hip, spine, or total body T-scores were used, but not when femoral neck T-score was used. CONCLUSIONS: Based on the limited sample size, optimal HU cutoff values of ~530, ~600, and ~640 HU for total hip, spine, or total body T-scores, respectively, were proposed. CT mandibular site HU measurement had diagnostic value in detecting osteoporosis when spine T-score was used but not when total hip, femoral neck, and total body T-scores were used. An optimal HU cutoff value of ~460 HU for spine T-score was proposed.

Correlation between dental implant insertion torque and mandibular alveolar bone density in osteopenic and osteoporotic subjects.

PURPOSE: Osteoporotic patients require particular attention during implant placement, and insertion torque (IT) has been established as a simple and noninvasive method to assess local bone quality and primary implant stability. This study aimed to test the hypothesis that IT was not significantly correlated with bone density, as assessed with computed tomography, in a group of osteopenic and osteoporotic patients. In addition, the hypothesis that IT was not significantly correlated with implant length was tested. MATERIALS AND METHODS: Fifty-three completely edentulous patients with compromised bone mineral density (osteoporotic or osteopenic) who required treatment with complete maxillary dentures and complete mandibular implantsupported overdentures participated in the study. Each patient received two screw-shaped self-tapping implants (Branemark Mark III TiUnite) at the mandibular canine regions. The IT of each implant during placement was recorded. The Pearson correlation between IT and implant site bone density (Hounsfield unit) obtained from presurgical computed tomographic scans was analyzed. The relationship between IT and implant length was also studied. RESULTS: IT was significantly correlated to implant site bone density but not to implant length. CONCLUSION: IT can be a viable and practical means to assess mandibular bone quality in patients with compromised general bone density.

Clinical considerations in managing severe tooth discoloration with porcelain veneers.

BACKGROUND: Although porcelain veneer has been proposed as the treatment of choice in cases of severe tooth discoloration, clinicians should consider a multidisciplinary approach when treating complex cases. Clinicians also need to understand the masking ability of veneer restorations. CASE DESCRIPTION: A 20-year-old woman had severe tooth discoloration, enamel hypoplasia and malocclusion. The patient first underwent orthodontic treatment to correct the dental alignment after the author extracted her hypoplastic first molars. The author then placed porcelain veneers with high-density alumina cores on the patient's maxillary and mandibular anterior teeth. The restorations were in service for seven years without complications. CONCLUSIONS: and CLINICAL IMPLICATIONS: Managing severe tooth discoloration requires thorough consideration of all patient factors, treatment provided in a logical sequence and the use of porcelain veneers with adequate masking ability.

Contrast ratios and masking ability of three types of ceramic veneers.

STATEMENT OF PROBLEM: Although ceramic veneers have been proven to be clinically successful in longevity studies, there is little information on the contrast ratios and masking ability of the available ceramic systems because dental laboratory technology and expensive experimental equipment are required for the investigation. Moreover, the complexity in understanding how to evaluate translucent ceramic materials may also explain why information in this area is limited. PURPOSE: The purpose of this study was to determine the contrast ratios and masking abilities of 3 types of all-ceramic veneers by measuring their luminance and color difference over white and black backgrounds. MATERIAL AND METHODS: Disk-shaped specimens (8-mm diameter x 0.7-mm thickness) of Shade A2 (Vita Lumin) of 3 types of all-ceramic systems: Procera (n=8), Empress 2 (n=8), and Vitadur Alpha (n=10) were fabricated. The luminance (as Y) and color (as CIE L*a*b*) of the specimens were measured with a colorimeter. The contrast ratio (CR=Yb/Yw), defined as the ratio of illuminance (Y) of the test material when it is placed on the black background (Yb) to the illuminance of the same material when it is placed over a white background (Yw), was determined. The masking ability of a specimen was evaluated by calculating the color difference (DeltaE) of the veneers over white and black backgrounds. Both CR and DeltaE* data were analyzed with 1-way ANOVA and the Tukey HSD test (alpha=.05). RESULTS: The mean contrast ratios (SD) of Procera, Empress 2, and Vitadur Alpha specimens were 0.50 (0.02), 0.46 (0.05), and 0.39 (0.02), respectively. CR values were significantly different among the 3 materials (P<.001). Procera veneers had a significantly higher CR compared to Empress 2 (P=.01) or Vitadur Alpha (P=.01), whereas the CR of Empress 2 was significantly higher than that of Vitadur Alpha (P=.046). Color difference (DeltaE*) (SD) of Procera, Empress 2, and Vitadur Alpha specimens over black and white backgrounds were 24.46 (1.03), 25.80 (1.03), and 31.08 (1.19), respectively. DeltaE* values were statistically different among the 3 materials (P<.001). Vitadur Alpha specimens had significantly higher DeltaE* when compared with Procera (P<.001) or Empress 2 (P<.001), whereas DeltaE* values between Procera and Empress 2 were not significantly different (P=.331). CONCLUSIONS: Vitadur Alpha had significantly lower contrast ratio and poorer masking ability compared to Procera or Empress 2. The clinical application of Vitadur Alpha as a veneer material over discolored teeth is cautioned. Although the contrast ratio of Procera was significantly higher than that of Empress 2, the masking abilities of these materials were not significantly different. The clinical application of these 2 ceramics as a veneer material may still be limited when applied over intense tooth discoloration because neither can fully mask the color of a black background.