PubMed Health⌕ Search

Biomedical subjects

Robert J Cronin

Publications and source records attributed to Robert J Cronin.

12 recordsLinked to original sources
PubMed2006

Consensus conference panel report: crown-height space guidelines for implant dentistry-part 2.

The International Congress of Oral Implantologists sponsored a consensus conference on the topic of Crown Height Space on June 26-27, 2004 in Las Vegas, Nevada. The panel communicated on several occasions before, during, and after the meeting, both as a group and among individuals. A consensus of one opinion was not developed for most issues. However, general guidelines emerged related to the topic. The following article is Part 2 of a summary of several of the guidelines that should be of benefit to the profession at large. (Part 1 appeared in Implant Dentistry 2005;14:312-321.).

Alveolar Ridge Augmentation↗
PubMed2005

Consensus conference panel report: crown-height space guidelines for implant dentistry-part 1.

The International Congress of Oral Implantologists sponsored a consensus conference on the topic of crown height space on June 26 and 27, 2004, in Las Vegas, Nevada. The panel communicated on several occasions before, during, and after the meeting, both as a group and among individuals. A consensus of 1 opinion was not developed for most issues. However, general guidelines emerged related to the topic. The following article is part 1 of a summary of several guidelines that should be of benefit to the profession at large.

Bite Force↗
PubMed2005

A radiographic assessment of progressive loading on bone around single osseointegrated implants in the posterior maxilla.

OBJECTIVES: The aim of this clinical study was to determine the effectiveness of progressive loading procedures on preserving crestal bone height and improving peri-implant bone density around maxillary implants restored with single premolar crowns by an accurate longitudinal radiographic assessment technique. MATERIALS AND METHODS: Twenty-three HA-coated, endosseous dental implants were placed in 20 subjects and permitted to heal for 5 months before surgical uncovering. The implants were randomly assigned to either an experimental or control group. Following a conventional healing period, the control group implants were restored with a metal ceramic crown and the experimental group implants underwent a progressive loading protocol. The experimental group was progressively loaded by increasing the height of the occlusal table in increments from a state of infraocclusion to full occlusion by adding acrylic resin to a heat-processed acrylic crown. The progressively loaded crowns were placed in infraocclusion for the first 2 months, light occlusion for the second 2 months, and full occlusion for the third 2 months. At this point, a metal ceramic crown replaced the acrylic crown. Standardized radiographs of each implant were made at the time of restoration, then after 2, 4, 6, 9, and 12 months of function. Digital image analysis and digital subtraction radiography were used to measure changes in crestal bone height and peri-implant bone density. RESULTS: The mean values of crestal bone height loss at 12 months were 0.2+/-0.27 mm for the progressively loaded implants and 0.59+/-0.27 for the conventionally loaded implants, and when tested with repeated-measure ANOVA across the time periods, the differences were statistically significant (P< or =0.05). The progressively loaded group showed a trend for higher bone density gain in the crestal area than the conventionally loaded group, but the conventionally loaded group showed a trend for higher bone density gain at the apex of the implants. CONCLUSION: The peri-implant bone around progressively loaded implants demonstrates less crestal bone loss than the bone around implants placed conventionally into full function. The peri-implant density measurements of the progressively loaded implants show continuous increase in peri-implant bone density by time.

Alveolar Process↗
PubMed2004

The hollow maxillary complete denture: a modified technique.

The severely atrophic maxilla poses a clinical challenge for fabrication of a successful complete denture. This article describes a novel method for fabrication of a hollow maxillary complete denture. It incorporates a clear, pressure-formed matrix of the trial denture external contours to facilitate the fabrication of a silicone putty cavity form. This cavity form ensures the appropriate dimensions of both the denture base acrylic resin for structural integrity and the denture base cavity for optimal weight reduction.

Acrylic Resins↗
PubMed2004

Retention characteristics of attachment systems for implant overdentures.

PURPOSE: The aim of this study was to compare the retention characteristics of various overdenture attachment systems commonly used to retain overdentures to dental implants. MATERIALS AND METHODS: An edentulous mandibular model was constructed incorporating 2 parallel 4.0 mm x 13 mm Branemark implants placed in the canine regions. Attachments were embedded in a metal-reinforced experimental overdenture designed to be dislodged from the model by a universal testing machine. Tensile dislodging force was applied to the overdenture at a cross-head speed of 50 mm/min. Five overdentures were constructed for each of the attachment systems. The attachments evaluated were the Hader bar & metal clip, Locator LR pink, Locator LR white, Spheroflex ball, Shiner magnet, Maxi magnet, Magnedisc magnet, ERA white, and ERA gray. Each apparatus was tested with 5 specimens per attachment system. Peak load-to-dislodgement was measured. Analysis of variance and Scheffe multiple comparison tests were applied to the data with alpha< or = 0.05 level of significance. RESULTS: Peak load-to-dislodgement for all attachment systems ranged from 3.68 +/- 1.32 N to 35.24 +/- 1.99 N. Strain-at-dislodgement, calculated from stress-strain curves, ranged from 0.78 +/- 0.20% to 2.78 +/- 0.5%. The ERA gray attachment demonstrated the greatest retention, with a peak load-to-dislodgement of 35.24 +/- 1.99 N, and a relatively low strain-at-dislodgement of 1.64 +/- 0.09%. Less retention was recorded for the Locator LR white, Spheroflex ball, Hader bar & metal clip, and ERA white systems. The Locator LR pink attachment demonstrated still less retention with a load-to-dislodgement of 12.33 +/- 1.28 N. Significantly high strain-at-dislodgement was recorded for the Hader bar & metal clip and Locator nylon attachment systems. The lowest dislodging loads and strains were recorded for the Shiner magnet, Maxi magnet, and Magnedisc magnet attachments. CONCLUSIONS: Results suggest that the attachment systems evaluated may be grouped into high (ERA gray), medium (Locator LR white, Spheroflex ball, Hader bar & metal clip, ERA white), low (Locator LR pink), and very low (Shiner magnet, Maxi magnet, Magnedisc magnet) retention characteristics.

Analysis of Variance↗
PubMed2003

The partially edentulous patient: fixed prosthodontics or implant treatment options.

The replacement of missing teeth by conventional fixed partial dentures or by implant supported prostheses occupies a major portion of the average restorative and prosthodontic practice. New materials, techniques, and technologies are constantly being added to our armamentarium. The demand for fixed prosthodontic patient services will continue to grow. It is the ultimate duty of the provider of these services to utilize an evidence-based rationale when determining the best possible treatment for the partially edentulous patient.

Dental Implants, Single-Tooth↗
PubMed2002

Characteristics and porcelain bond strength of (Ti,Al)N coating on dental alloys.

The effect of a novel titanium-aluminum nitride film, or (Ti,Al)N film, on the bond strength between a dental porcelain and two nickel-based dental alloy substrates was investigated. A thin layer of (Ti,Al)N film was deposited on flat metal samples using a reactive radio-frequency sputtering method. A uniform thickness of porcelain was applied to the film- coated metal samples. Metal-ceramic specimens were subjected to three-point bending, and failure loads were recorded. Bond strengths between the porcelain and (Ti,Al)N-coated metal alloys ranged from 159.0 +/- 11.7 N to 278.0 +/- 12.3 N. These values were significantly greater (p< 0.05) than bond strengths recorded for control samples that did not incorporate the (Ti,Al)N film. An electron probe microanalyzer with a line profile mode was used to characterize the interface between the (Ti,Al)N film and the porcelain. Results of this investigation suggest that the (Ti,Al)N film (1) increases the flexural bond strength between dental porcelain and nickel-based alloy substrates by permitting elemental diffusion, (2) interferes with the surface oxide formation that characteristically originates from the nickel-based metal alloy substrate, and (3) provides an appropriate oxide layer for porcelain application.

Alloys↗