Effect of loading mode on bond strength of orthodontic brackets bonded with 2 systems.

INTRODUCTION: A new orthodontic bracket bonding method or material invariably spawns bond strength studies examining the efficacy of the innovation. The primary purpose of this project was to ascertain whether the mode of in-vitro bracket debonding used in a study affects the measured bond strength. The secondary aim was to compare the bond strengths of 2 different bonding systems. METHODS: Flattened stainless steel orthodontic brackets were bonded to flattened bovine enamel with a resin composite bonding agent (Transbond XT, 3M Unitek, Monrovia, Calif). The enamel was prepared with traditional acid etching and priming (37% phosphoric acid gel and Transbond XT Primer, 3M Unitek) or a single-step method (Transbond Plus, 3M Unitek) that combined etching and priming. Cement thickness was kept constant, and bonding was done under controlled temperature and humidity. Brackets were debonded in shear-peel, tension, or torsion. RESULTS: When tested in shear-peel mode, traditional etching and priming produced a stronger bond than the single-step self-etch system. When tested in tension, the traditional bond was weaker than the single-step bond, and when tested in torsion, the bond strengths were similar. CONCLUSIONS: Bond strength can vary depending on the method of testing. Claims of clinical efficacy might not be valid.     

In vitro biofilm formation on the surface of resin-based dentine adhesives

Prevention of root caries on exposed root surfaces in the aging population is a significant challenge. Bonding resins can be applied to exposed root surfaces as sealants; however, minimal data exists regarding biofilm formation on the surface of these resins. We hypothesized that an antibacterial dentine-bonding resin containing methacryloxydodecyl-pyridiniumbromide (MDPB) may reduce biofilm formation. Biofilms were produced in pooled stimulated natural whole saliva, supplemented with 1% sucrose, on the surface of 5 dentine-bonding resins (Clearfil SE, OptiBond Solo, Protect Bond, Protect Bond Primer, and Xeno III) using untreated root surfaces as controls. Biofilms were stained using the Live:Dead Baclight bacterial viability stain, viewed with confocal microscopy, and analyzed using ImageJ image-analysis software. Resin surfaces encouraged attachment of live bacteria compared with root surfaces. All resins showed similar bacterial colonization in sections adjacent to the resin surface, but in the central and outer portions of biofilms, Xeno III and Protect Bond Primer showed a viable bacterial load similar to that of the root surface. Fluoride-releasing resins (OptiBond Solo/Protect Bond) did not show reduced biofilm formation. Thus, antibacterial agents within the resins have a minimal effect on biofilm formation, particularly when directly adjacent to the root surface.     

Repeated oral hygiene instructions alone, or in combination with metronidazole dental gel with or without subgingival scaling in adult periodontitis patients: a one-year clinical study

The aims of the present study were to evaluate the clinical efficacy of, and to monitor microbiologically, repeated oral hygiene instructions alone or in combination with metronidazole 25% gel or subgingival scaling with or without metronidazole gel in treatment of new, residual or recurrent periodontal pockets in previously treated adult periodontitis patients. Ten suitable patients were included in this randomized single-blind clinical study with an intra-individual design. Clinical parameters were measured before and at 1, 3, 6, 9 and 12 months after treatment. Subgingival plaque samples were taken at every examination from one selected site in each quadrant. Smears from plaque samples were silver-stained and differential counting was performed under light microscopy at 1000X magnification. Four treatment modalities: (i) oral hygiene instruction (OHI) alone; (ii) OHI and metronidazole dental gel; (iii) OHI and subgingival scaling; (iv) OHI and subgingival scaling plus metronidazole gel, were randomly assigned to one quadrant of each patient. At the 12-month examination, the mean reductions in probing pocket depth were 2.6 mm after OHI alone, 2.8 mm after OHI and metronidazole gel, 3.3 mm after OHI and subgingival scaling and 2.6 mm after oral OHI and subgingival scaling plus metronidazole gel. The mean gains in probing attachment level were 2.2 mm, 1.9 mm, 2.7 mm and 1.6 mm, respectively. Although there were statistically significant differences in treatment responses between some treatment modalities at some time points, these were not considered to be clinically significant. Differential counts showed a shift towards a healthy microflora in response to all treatment modalities. From the 12-month results, it was concluded that the metronidazole 25% gel produced positive effects on the clinical parameters and on the subgingival plaque microbiological composition in new, residual or recurrent pockets in previously treated chronic periodontitis patients. However, the metronidazole gel alone or in combination with scaling does not seem to have any additional clinically significant therapeutic effects over and above those derived from improved oral hygiene resulting from monthly recalls, with or without subgingival scaling.     

Effect of two-step adhesive systems on inhibition of secondary caries around fluoride-releasing resin composite restorations in root dentine

OBJECTIVE: The purpose of this study was to investigate the effect of two-step adhesive systems on secondary caries inhibition around fluoride-releasing materials in vitro. METHODS: Two self-etching primer systems, Clearfil SE Bond (SE) and UniFil Bond (UB), and two one-bottle systems with a total-etch wet-bonding technique, Single Bond (SB) and One-Step (OS), were used prior to placement of resin composites either with (Reactmer) or without (Z100) fluoride release. Class V cavities prepared in extracted human premolars were restored with various combinations of materials: Reactmer/SE, Reactmer/UB, Reactmer/SB, Reactmer/OS, Z100/SE, Z100/UB, Z100/SB and Z100/OS. After storage for 14 days, the restored teeth were incubated in bacterial medium containing sucrose with Streptoccus mutans for 2 weeks. Water sorption and desorption of the adhesives and fluoride release from the resins either coated with adhesive or uncoated were also determined. RESULTS: The one-bottle groups showed higher water sorption and desorption than the self-etching primer groups. Although fluoride release from the Reactmer specimens was suppressed by the adhesive coating, the one-bottle groups allowed significantly higher fluoride release than the self-etching primer groups. On microradiographs, the radio-opaque layers adjacent to the Reactmer restorations were thick and clear, while the layers adjacent to the Z100 restorations were thin and unclear. For the Reactmer restorations, the radio-opaque layers associated with the one-bottle groups were significantly thicker than for the self-etching primer groups. CONCLUSIONS: These results indicated that the use of one-bottle wet-bonding systems for bonding of fluoride-releasing resin composites to dentine may contribute to inhibit secondary caries compared to self-etching primer systems.     

The use of Ormocer as an alternative material for bonding orthodontic brackets

As new adhesives, composite resins, and bonding techniques were introduced, orthodontists adopted some of these innovations and added them to their armamentarium. The purpose of this study was to compare the shear bond strength (SBS) of two adhesive materials; one with an organically modified ceramic matrix, Admira (Voco, Cuxhaven, Germany) and another that contains the traditional Bis GMA matrix namely Transbond XT (3M Unitek, Monrovia, Calif). The new materials have a lower wear rate and are more biocompatible than traditional composites. Forty molar teeth were randomly divided into two groups: 20 teeth bonded with the Transbond adhesive system and the other 20 teeth with the Admira bonding system. Student's t-test was used to compare the SBS of the two adhesives. Significance was predetermined at P < or = .05. The results of the t-test comparisons (t = 0.489) of the SBS indicated that there was no significant (P = .628) difference between the two adhesives tested. The mean SBS for Admira was 5.1 +/- 3.3 MPa and that for Transbond XT was 4.6 +/- 3.2 MPa. It was concluded that the new material, Ormocer, which is an organically modified ceramic restorative material can potentially have orthodontic applications if available in a more flowable paste. These new materials are more biocompatible and have lower wear rate including bonding orthodontic brackets to teeth.     

What do patients expect from complete dentures?

OBJECTIVES: An investigation was undertaken with the aim of determining whether patients wearing complete dentures in dental hospital (DH) and dental practice (DP) had different expectations from their dentures, together with their requirements for information about denture construction and oral and denture care. METHODS: A total of 214 edentulous patients, with a mean age of 69 years, from DP (125) and DH (89) participated in the questionnaire-based study. A valid questionnaire (P-DEQ) was constructed which demonstrated good test-retest reliability (Cronbach's alpha 0.86). The P-DEQ sought to determine how patients responded to a series of questions related to what dentists are urged to achieve with complete dentures. The questions covered not only what might be termed "normative" expectations but also patients' perceived needs for further information about the stages of prosthodontic treatment and oral or denture care. RESULTS: Significant differences (p< or =0.001) emerged between the two groups; 82% of the DH group thought it essential that their dentures caused no pain compared with 59% of the DP group; for "absence of slackness" (DH 87%; DP 65%), and "good bite" (DH 82%; DP 55%). No significant differences emerged for the other parameters investigated, but both groups had high expectations for ease of chewing, speech, and good appearance. Differences (p<0.05) between the groups also emerged with respect to the demand for more information regarding the stages involved in denture construction (DH 57%, DP 76%) and how to care for dentures (DH 75%, DP 89%). Large proportions of patients from both groups would prefer to have more information about the selection of teeth (71% DH, 72% DP), and how to care for their mouths (84% DH, 86% DP), but there were no differences between the groups in these parameters. CONCLUSIONS: Most patient expectations appear to equate with the normative view expressed in standard prosthodontic texts. However, expectations may differ not only between individuals but also between patient groups managed in teaching hospital and DP settings. Edentulous patients also need information regarding the stages involved in denture construction and how to care for their mouths and dentures. This may have implications for the management of edentulous patients in DP and dental hospital.     

Pattern of tooth loss in recipients of free dental treatment at the University Hospital of Amman, Jordan

The aim of this study is to document reasons for tooth loss in disadvantaged Jordanians who seek free dental care at the University Hospital/Dental Clinics. A 4-year (1998-2001) prospective study was undertaken involving 2200 randomly selected patients from this subpopulation. Of their 3069 lost teeth, 46.9% were lost due to caries and its sequel; 18% were lost because of periodontal disease; 8% were lost for a combination of caries and periodontal disease; 19.4% for pre-prosthetic reasons; 4% for orthodontic reasons; 2.8% for eruption problems and 0.7% due to trauma. Logistic regression analysis for reasons of tooth loss in this sector revealed that caries and its sequel was the predominant cause of tooth loss in patients 相似文献   

Effect of bur type on microtensile bond strengths of self-etching systems to human dentin

PURPOSE: To compare the microtensile bond strength (microTBS) of five adhesives to human dentin prepared with 600-grit SiC abrasive paper (SiC), a diamond rotary instrument, or a carbide bur. The null hypothesis was that different cavity preparation instruments do not affect adhesion of resin adhesives. MATERIALS AND METHODS: Human molars (n = 45) were randomly divided into three groups according to surface treatment. Each group was bonded using a total-etch adhesive (Single Bond, 3M ESPE), one of three self-etching primer systems (Clearfil SE Bond or ABF, Kuraray; Imperva Fluorobond, Shofu), or a self-etching adhesive (One-Up Bond F, Tokuyama). A 4-mm composite crown was built over the bonded surface. Specimens were stored in water for 24 h at 37 degrees C. They were sectioned into 0.7-mm-thick slabs, trimmed to a cross-sectional area of 1 mm2, and loaded to failure at a crosshead speed of 1 mm/min using a tabletop tester (EZ-Test, Shimadzu). Microtensile bond strength data were analyzed using analysis of variance and Fisher's PLSD test. RESULTS: Surface preparation using a carbide bur generally yielded higher bond strengths than preparation using either a diamond rotary instrument or SiC abrasive paper. SE Bond had the highest mean microTBS of the five adhesives tested. CONCLUSION: Resin-dentin bond strengths can be affected by the type of instrument used to prepare the tooth. Specifically, higher bond strengths might be achieved by using carbide burs rather than diamond cutting instruments.     

Treatment of inflammatory salivary gland diseases by using intraductal UV irradiation

A novel technique is offered for treatment of sialadenitis. Ultraviolet irradiation conductors are inserted into the gland via its major duct for subsequent intracorporeal UV therapy of the gland. The results of the treatment are analyzed in 57 cases of sialadenitis observed during 1 to 2.5 years. The technique proved effective enough to be recommended for practical application.