Dental Corporation Research Articles

Effect of aging on tear strength and cytotoxicity of soft denture lining materials; in vitro.

PURPOSEThe aim of this in vitro study was to evaluate the effect of aging on the tear strength and cytotoxicity of four soft denture lining materials.MATERIALS AND METHODSFour commonly used soft denture lining materials, (Coe-Comfort™ GC America Inc., Alsip, IL, USA; Coe-Soft™ GC America Inc., Alsip, IL, USA; Visco-gel Dentsply Caulk Milford, DE, USA; and Sofreliner Tough M Tokuyama Dental Corporation Tokyo, Japan) were selected. Sixty trouser-leg designed specimens per lining material were fabricated using a stainless steel mold for tear strength testing. The specimens were divided into non-thermocycling and 1000-, and 3000- thermocycling groups. For the cytotoxicity test, twenty-four disk shaped specimens per material were fabricated using a stainless steel mold. The specimens were soaked in normal saline solution for 24 h, 48 h and 72 h. Cytotoxicity was measured by XTT assay in L929 mouse fibroblasts. Data were analyzed by two way analysis of variance and Dunnett's test (P<.05).RESULTSBefore thermocycling, Sofreliner Tough M (10.36 ± 1.00 N) had the highest tear strength value while Coe-Comfort™ (0.46 ± 0.10 N) had the lowest. After 3000 cycles, Sofreliner Tough M (9.65 ± 1.66 N) presented the highest value and Coe-Comfort™ (0.42 ± 0.08 N) the lowest. Sofreliner Tough M, in all incubation periods was the least toxic with significant differences compared to all other materials (P<.05). Coe-Comfort™, Coe-Soft™, and Sofreliner Tough M did not show any significant differences within their material group for all incubation periods.CONCLUSIONThis in vitro study revealed that aging can affect both the tear strength and cytotoxicity of soft denture materials depending on the composition.

Evaluation of cytotoxicity of six different flowable composites with the methyl tetrazolium test method

Abstract Background: The aim of this study was to investigate the cytotoxicity of six different flowable composites with the methyl tetrazolium test (MTT). Materials and Methods: For MTT, six different flowable composites (Bisco Aelite, Bisco Inc., USA; Esthet X Flow, Dentsply, USA; Filtek™ Supreme XT Flowable Restorative, 3M Espe, USA; Gradia ® Direct Flo, GC, USA; Estelite ® Flow Quick, Tokuyama Dental Corporation, Japan; and Clearfil Majesty Flow, Kuraray Medical Inc., Japan) were prepared according to the manufacturer’s instructions in standard Teflon disks (2 mm × 5 mm) and the samples were extracted in 7 ml of Basal Medium Eagle with 10% new born calf serum and 5% penicillin streptomycin gentamisin for 24 h. In the experiments: The L929 cells were plated (25.000 cells/ml) in wells of 96 well-dishes and maintained in a humidified incubator for 24 h at 37°C, 5% CO2, and 95% of air. After 24 h incubation of the cells, the incubation medium was replaced by the immersed medium in which the samples were stored. Then L929 cells were incubated in contact with evaluates for 24 h. The cell mitochondrial activity was evaluated by the MTT. 12 well used for each specimen and MTT tests applied 2 times. The data were submitted to the statistically analyzed by one-way ANOVA and Tukey’s honestly significant difference (HSD) tests. Results: According to the results of MTT test with L-929 fibroblasts demonstrated that all freshly prepared flowable composites did not reduce vital cell numbers (P&gt;0.05) in comparison to control group. Conclusion: This study revealed important information for clinical applications of flowable composites in dentistry.

‘Responsibility that I relish’

In a first for Vital, we interview an Operations Assistant, Chloe Campbell, who works in the head office of a glamorous but patient-focused UK dental corporate.

Bond Strength of Soft Liners to Fiber‐Reinforced Denture‐Base Resin

This study evaluated bond strengths of four soft liners to fiber-reinforced (FR) and unreinforced poly methyl(methacrylate) (PMMA) denture-base resin. The autopolymerized denture-base resin Palapress Vario (Heraus Kulzer GmbH, Hanau, Germany) was used as the substrate (15 × 15 × 5 mm³). The test group consisted of substrates reinforced with porous PMMA preimpregnated unidirectional glass fibers (Stick [StickTech, Turku, Finland]) (PMMA + FR group), and the control group was unreinforced acrylic resin (PMMA group) (n = 80 per group). One of four soft liners (Ufi Gel SC [Voco, Cuxhaven, Germany], Sofreliner Tough [Tokuyama Dental Corporation, Tokyo, Japan], Vertex SoftSil 25 [Vertex-Dental B.V., Zeist, The Netherlands], and Eversoft [Dentsply Austenal, York, PA]) was placed and cured between two substrates using a polyethylene ring (10 mm inner radius, 3 mm height). Tensile bond strength tests (crosshead speed = 10 mm/min) were performed, and the results were analyzed using analysis of variance followed by Tukey's test (p= 0.05). Fracture surfaces were categorized as adhesive or cohesive-mixed modes, and failure types were statistically analyzed using chi-square test. FR did not affect the bond strength results significantly (p > 0.05) except for Ufi Gel SC. Significant differences in bond strength were found among the reline materials (p < 0.001). FR specimens showed a significantly higher number of cohesive-mixed fractures compared to unreinforced specimens (p < 0.05), except for plasticized acrylic-based reline material (Eversoft [Dentsply Austenal]), which showed fewer cohesive-mixed failures with FR. The choice of appropriate reline material system with FR acrylic resin is important for the soft liner/denture-base polymer bond. Glass FR did not have a decreasing effect on the bond strength, except for Ufi Gel SC.

Correlation between Laser Fluorescence Readings and Volume of Tooth Preparation in Incipient Occlusal Caries In Vitro

This study evaluated the correlation between laser fluorescence readings and the extent of incipient occlusal caries as measured by the volume of tooth preparation in vitro. One hundred and three permanent molars and premolars containing incipient occlusal pit-and-fissure caries and sound occlusal surfaces (1/4 of the sample, control) were selected. DIAGNOdent (KaVo Dental Corporation, Lake Zurich, IL, USA) readings were obtained according to manufacturer instructions. Caries was removed with 1/4 round burs in high speed. The volume of tooth preparation was measured using a surrogate measure based on the amount of composite needed to fill the preparations. Sensitivity and specificity using different cutoff values were calculated for lesions/preparations extending into dentin. The results were analyzed statistically. The Pearson correlation for preparation volume and DIAGNOdent reading measurements was low (r = 0.285). Sensitivity and specificity of DIAGNOdent for detection of dentinal lesions were 0.83 and 0.60, and 0.66 and 0.73 for the cutoff values of 20 and 30, respectively. Within the limitations of this study, laser fluorescence measured with DIAGNOdent does not correlate well with extent of carious tooth structure in incipient occlusal caries. Clinicians should not rely only on DIAGNOdent readings to determine the extension of incipient occlusal caries.

Effectiveness of Pit and Fissure Sealants in Reducing White Spot Lesions during Orthodontic Treatment

A pilot investigation was performed to test the null hypothesis that highly filled (58%) resin sealants do not prevent white spot lesions in patients undergoing active orthodontic treatment. A split-mouth design was applied to 60 healthy patients, with the sealant randomly allocated to either the right or the left side of each jaw. The sealant was applied to the incisors and canines from the gingival surface of the bracket to the free gingival margin. The contralateral teeth had the same type of bracket with no sealant. Sealants were placed on the experimental teeth 2 weeks to 3 months after initial bonding and were removed after 15 to 18 months. Intraoral photographs, visual assessments, and DIAGNOdent (KaVo Dental Corporation, Lake Zurich, Ill) measurements were used to assess white spot lesions after sealant removal. Six lesions on the teeth with sealants were identified visually, compared with 22 lesions on the teeth without sealants. The teeth without sealants had 3.8 times the number of white spot lesions than were noted on the sealed teeth. These sealants showed no visible signs of discoloration. The DIAGNOdent measured statistically significant differences between sealed and unsealed teeth in the maxilla (P < .001) and in the mandible (P = .010). DIAGNOdent measurements also showed a difference between sealed and unsealed teeth after the 28 teeth with visible lesions were excluded. The hypothesis was rejected. Ultraseal XT Plus clear sealant (Ultradent Products, South Jordon, Utah) produced a significant reduction in enamel demineralization during fixed orthodontic treatment and should be considered for use by clinicians to minimize white spot lesions.

UK's largest dental corporate sold to US bank

UK's largest dental corporate sold to US bank

Treatment outcomes in 3 modes of orthodontic practice

This study examined differences in pretreatment severity and treatment outcome among orthodontic patients treated in 3 different practice-management modes. Samples of pretreatment (T1) and end of treatment (T2) study casts were selected from traditional private practices (TPP, 3 offices, 81 cases), a dental corporation (COMP, 2 offices, 53 cases), and a dental management service organization (DMSO, 1 office, 36 cases). Orthodontic specialists had treated all patients. Cases were initially selected on a consecutive start basis. From each practice, the first 30 cases satisfying the study criteria were included in the sample. The T1 and T2 study casts were evaluated with the PAR and HLD indexes. The PAR and HLD indexes showed a high level of agreement on T1 cast scores but not on the T2 casts. Mean T1 scores were highest in the COMP cases, followed by the DMSO and the TPP cases. T2 scores were lowest in the TPP cases, followed by the DMSO and the COMP cases. The percentage of PAR score reduction showed that, in all 3 modes, patients were treated to a high standard. (Am J Orthod Dentofacial Orthop 2002;121:176-184)

Treatment outcomes in 3 modes of orthodontic practice

<h2>Abstract</h2> This study examined differences in pretreatment severity and treatment outcome among orthodontic patients treated in 3 different practice-management modes. Samples of pretreatment (T1) and end of treatment (T2) study casts were selected from traditional private practices (TPP, 3 offices, 81 cases), a dental corporation (COMP, 2 offices, 53 cases), and a dental management service organization (DMSO, 1 office, 36 cases). Orthodontic specialists had treated all patients. Cases were initially selected on a consecutive start basis. From each practice, the first 30 cases satisfying the study criteria were included in the sample. The T1 and T2 study casts were evaluated with the PAR and HLD indexes. The PAR and HLD indexes showed a high level of agreement on T1 cast scores but not on the T2 casts. Mean T1 scores were highest in the COMP cases, followed by the DMSO and the TPP cases. T2 scores were lowest in the TPP cases, followed by the DMSO and the COMP cases. The percentage of PAR score reduction showed that, in all 3 modes, patients were treated to a high standard. (Am J Orthod Dentofacial Orthop 2002;121:176-184)