In vitro evaluation of the implant abutment connection sealing capability of different implant systems.

This study sought to evaluate the sealing capability of the implant abutment connection of different dental implant systems. Five Nobel Replace select, Straumann and Intra-lock implants of approximately 4.5 mm diameter with their respective abutments were provided by the manufacturers. A calibration curve was determined by placing toluidine blue (TB) increments of 0.1 microL into 1.5 mL of distilled water and recording its absorbance in a spectrophotometer until reaching 0.7 microL. Then, 0.7 microL of TB was placed in the deepest portion of each implant's internal screw, the abutments were adapted to the implant according to the manufacturer's instructions and the specimens were placed in vials with 1.5 mL of distilled water. Spectrophotometric analysis was performed at 1, 3, 6, 24, 48, 72, 96 and 144 h. Statistical analysis was performed by One-way anova at 95% level of significance. The calibration curve was linear with respect to the TB amount in 1.5 microL distilled water (R(2) = 0.9961). All implant abutment systems presented an increase in absorbance as a function of time. As time elapsed in vitro, significantly higher amounts of TB was released from the Straumann and Nobel Replace Select connection systems (P < 0.0001). Leakage was significant between the groups. Despite controlled torquing, the seal between the implant body and the abutment could not be maintained in all three of the systems tested.

Evaluation of transitional implant stabilized overdentures: a case series report.

Transitional implants (TI) can immediately improve the stability and retention of existing unstable mandibular complete dentures. This study evaluated the improvement of mandibular complete denture stability and retention with the use of TI. Three TIs were placed in the intraforaminal region of the edentulous mandible of seven patients (three men, four women; mean age 69.7 years). The patients' existing mandibular complete dentures were immediately modified to TI-stabilized overdentures. Their masticatory movements (mandibular movements during mastication) were measured using a commercially available tracking device (BioPACK, Bioresearch, Japan), both before TI placement and about 1 month after delivery of the TI-stabilized overdentures. The mean time of each chewing phase (opening, closing, and occluding) and coefficients of variation were calculated. The patients also completed a questionnaire about the foods they could chew and indicated on a 100 mm Visual Analog Scale (VAS) their personal levels of comfort, ease of chewing, speech, and stability. For masticatory movements, there were no significant differences (P > 0.05) between the TI-stabilized overdentures and existing complete dentures. However, the number of foods that could be chewed increased, and the stability and comfort were reported as improved with the TI-stabilized overdentures. Using TIs, the stability and comfort of the existing mandibular complete dentures studied in this report could be immediately improved.

Multi-unit fixed partial denture for a bilateral cleft palate patient: a clinical report.

Patients with cleft palates eventually require definitive fixed or removable dental prostheses after the maintenance of arch alignment and occlusal relationship during adolescence. This case report presents application of a resin composite veneered fixed partial denture utilized as a definitive prosthesis for a bilateral cleft palate patient after stable occlusion had been established orthodontically. The composite veneered long span fixed partial denture provides adequate aesthetics and function.

Comparative study of maxillary complete dentures constructed of metal base and metal structure framework.

A removable denture designed using a three-dimensional cast metal framework (hereafter referred to as the 'structurally designed' denture) could extend denture longevity because it is unbreakable and easy to adjust. The aim of the present clinical study was to compare two types of maxillary removable dentures: conventional dentures and structurally designed denture. One edentulous and five partially dentate patients were fitted with two maxillary dentures made from the same impression and same occlusal relationship. About 20 days after delivery of the denture, masticatory analysis was conducted chewing phase (open, closed, and occluded); coefficients of variation and average variation were calculated. Denture vibration during tapping was then measured using an accelerometer. The patients were also interviewed about comfort, ease of chewing, speech, stability, aesthetics and preference for regular use. For both masticatory movements and denture vibration, there were no significant differences (P>0.1) between the conventional denture and the structural design denture. In evaluating the dentures according to each criteria, the significant superiority of one denture over the other could not be determined. However, all patients subjectively preferred the structurally designed dentures for regular use. According to these findings, structurally designed dentures do not appear to have any particular physiological problems as compared with the conventional dentures.

Impression procedure for creating a partial auricular prosthesis.

Severe anatomic undercuts associated with tissue remnants or a defect site can often be an obstacle in achieving an accurate impression for a facial prosthesis. This article describes a procedure that overcomes the problems encountered in achieving an accurate impression. The distinct properties of 2 impression materials are applied to create a 3-piece impression that can be reassembled to develop an accurate stone master cast.

Effect of sandblasting and silicoating on bond strength of polymer-glass composite to cast titanium.

STATEMENT OF PROBLEM: There is little information regarding the mechanical and chemical retention of polymer-glass composite to cast titanium. PURPOSE: This study examined whether sandblasting in conjunction with silicoating improves the bond strength of the polymer-glass composite to cast titanium. MATERIALS AND METHODS: Disk patterns (10 mm in diameter, 2.5 mm thick) were cast with commercially pure titanium (CP Ti) and Type IV gold alloy. Three pretreatments were applied: 50 microm Al(2)O(3) sandblasting (50 SB), 250 microm Al(2)O(3) sandblasting (250 SB), and 600-grit SiC paper polishing (600 SiC). After surface preparation, the Siloc system (silicoating) was applied on the disks. The 50 SB specimens without Siloc system were also prepared as controls. Then sticky tape with a circular hole (4.76 mm diameter) was placed onto the disk to define the bonding area. Artglass (polymer-glass) opaque, dentin, and enamel composites were applied using Teflon matrices and then light-polymerized. Shear bond strength (n = 8) was determined at a crosshead speed of 5 mm/min. Results were analyzed statistically with 2-way ANOVA and the Tukey-Kramer test (alpha=.05). RESULTS: The Siloc system significantly (P <.05) improved the mean shear bond strength of Artglass to both metals in the 50 SB specimens. Statistical differences (P <.05) in shear bond strength were found among surface treatments for the silicoated CP Ti specimens, in which 250 SB specimens yielded the greatest bond strength. The Type IV specimens treated with Siloc system showed no significant differences in shear bond strength between the 50 SB and the 250 SB specimens. CONCLUSION: Sandblasting with coarser alumina particles in conjunction with silicoating significantly enhanced bond strength of polymer-glass composite to cast titanium.

The new removable denture patient: treatment procedures.

Dentists are beginning to see a new type of patient who requires removable prosthodontic rehabilitation. These patients are the result of both increases in longevity and dental treatment that has retained teeth, despite the onslaught of caries and periodontal disease. The current procedures for transitioning patients into removable prostheses can be modified for this new group of patients. This article presents a transition procedure for patients who are receiving removable prostheses, which dissociates the surgical phase of treatment from the prosthetic stage. The patient's existing teeth are incorporated into a removable prosthesis in a way that ensures the exact replication of the tooth position in the oral cavity. This method addresses many of the inadequacies of current procedures while at the same time requiring a minimum of chair time. Even with this procedure, this transition is still difficult for the patient.

Constructing direct porcelain laminate veneer provisionals.

Historically, teeth prepared for indirect restorations are protected by some type of provisional restoration. This is not always the case for teeth prepared for porcelain laminate veneers because construction of temporaries can be time-consuming. This case report illustrates a quick technique for fabricating a direct composite veneer provisional for teeth prepared for porcelain laminate veneers.

Adjunctive caries control in overdenture abutment teeth: a new modality.

Controlling caries in decoronated abutment teeth is an ongoing concern for the restorative dentist. In the ideal situation, the overdenture abutment is restored with a cast coping, but economic constraints may rule this out in favor of a prefabricated overdenture attachment. This article describes how caries may be controlled in exposed dentin when such a restoration is used.

Human beta 2 chain of laminin (formerly S chain): cDNA cloning, chromosomal localization, and expression in carcinomas.

Overlapping cDNA clones that encode the full-length human laminin beta 2 chain, formerly called the S chain, were isolated. The cDNA of 5680 nt contains a 5391-nt open reading frame encoding 1797 amino acids. At the amino terminus is a 32-amino-acid signal peptide that is followed by the mature beta 2 chain polypeptide of 1765 amino acids with a calculated molecular mass of 192,389 Da. The human beta 2 chain is predicted to have all of the seven structural domains typical of the beta chains of laminin, including the short cysteine-rich alpha region. The amino acid sequence of human beta 2 chain showed 86.1% sequence identity to the rat beta 2 chain, 50.0% to the human beta 1 chain, and 36.3% to the human beta 3 chain. The greatest sequence identity was in domains VI, V, and III. The sequence of a 24-amino-acid peptide fragment isolated from the beta 2 chain of laminin purified from human amniotic basement membrane matched the sequence predicted from the cDNA, confirming that the cDNA encodes human beta 2 laminin. The cDNA was used to assign the gene (LAMB2) to human chromosome 3p21 by in situ hybridization. It is not linked to genes for human laminin chains alpha 1, beta 1, and gamma 1 or other known laminin genes. Immunostaining showed that the beta 2 chain is localized to the smooth muscle basement membranes of the arteries, while the homologous beta 1 chain is confined to the subendothelial basement membranes. The beta 2 chain was found in the basement membranes of ovarian carcinomas but not colon carcinomas. These results indicate that the expression of the beta 2 chain gene is tightly regulated in normal human tissues and in disease.