Thesis
Efficacy of direct restorative materials in proximal box elevation on the margin quality and fracture resistance of molars restored with CAD/CAM onlays
University of Iowa
Master of Science (MS), University of Iowa
Spring 2018
DOI: 10.17077/etd.5213gkyb
Abstract
<p>The purpose of this study was to investigate the effect of four direct restorative materials that can be used in the proximal box elevation (PBE) technique. Materials and Methods: Seventy-five molar teeth were randomly assigned to one of five groups (n=15): Type II glass-ionomer (GI), Type II resin-modified glass-ionomer (RMGI), resin-based composite (RBC), bulk fill (BF) resin-based composite, and a control with no box elevation procedure. Specimens were prepared for a standard CAD-CAM ceramic onlay preparation with mesial cervical margins located 1 mm above CEJ (cemento-enamel junction) and distal cervical margins located 2 mm below the CEJ. PBE was used to elevate the distal margins to 1 mm above the CEJ in all groups except the control group. For the control group the onlay margin was placed directly on the prepared distal tooth without PBE. A Lava UltimateTM, CAD/CAM Resin, nano-Ceramic onlay Restorative (LAVU) was milled and bonded on all specimens with RelyX UltimateTMAdhesive Resin Cement. The margin quality of the tooth-PBE material and PBE material-onlay interface was evaluated with scanning electron microscopy (SEM) using epoxy replicas before and after mechanical loading (100,000 cycles, 1.2 Hz at 65N). In addition to margin quality, the fracture resistance of each group was measured using a universal testing machine. Fracture pattern was recorded by visual examination. One-way ANOVA was performed followed by Least Square Means. Results: For dentin margins, a statistically significant difference was detected between RMGI and control group at baseline (p=0.0442). All other groups GI, RBC, and BF showed no difference to control at baseline (p>0.05). No statistical significance was observed among groups for post-mechanical fatigue (p=0.8735). For onlay margins, no statistical significance was observed among groups for pre-mechanical fatigue, post-mechanical fatigue, or change (p=0.9713, p=0.528, p= 0.4385 respectively). No significant difference was observed for the fracture resistance among groups or for the type of break by material used (p=0.1593, p=0.77 respectively). Conclusion: Within the parameters of this study, following mechanical fatigue, the materials used for PBE: resin-modified glass-ionomer and glass-ionomer, resin-based composite and bulk-fill composite, did not influence results in terms of margin quality and fracture resistance. Therefore, collective findings suggest that these materials might be suitable for proximal box elevation procedures. Nevertheless, clinical caution is recommended with any PBE procedure and further testing of GI materials is needed.</p>
Details
- Title: Subtitle
- Efficacy of direct restorative materials in proximal box elevation on the margin quality and fracture resistance of molars restored with CAD/CAM onlays
- Creators
- Thomas David Grubbs - University of Iowa
- Contributors
- Erica Teixeira (Advisor)Marcos Vargas (Committee Member)Justine Kolker (Committee Member)
- Resource Type
- Thesis
- Degree Awarded
- Master of Science (MS), University of Iowa
- Degree in
- Oral Science
- Date degree season
- Spring 2018
- DOI
- 10.17077/etd.5213gkyb
- Publisher
- University of Iowa
- Number of pages
- xi, 69 pages
- Copyright
- Copyright © 2018 Thomas David Grubbs
- Language
- English
- Date submitted
- 09/05/2018
- Description illustrations
- illustrations (some color)
- Description bibliographic
- Includes bibliographical references (pages 67-69).
- Public Abstract (ETD)
My thesis title is, “Efficacy of direct restorative materials in proximal box elevation on the margin quality and fracture strength of molars restored with CAD composite onlays.” Translation of this title, “effectively restoring severely damaged teeth with single-visit crowns.”
Every general dentist and a host of patients face clinical realities when attempting to restore and keep severely damaged teeth. The multitude of different treatment modalities used to restore teeth, all deserve consideration. Considering restorative options provides the patient ideal results. To enhance the restoration process and outcome of teeth with damage below the gum-line it is normally recommended that teeth undergo surgical margin elevation or orthodontics, so more tooth structure is available to place restorative materials on. Surgery and orthodontics are time and cash consuming. In specific cases, depending oral factors, surgical marginal elevation or orthodontic treatment may not be required. A technique to restore these cases indirectly, the proximal box elevation technique (PBE), may be a promising alternative. This PBE procedure has the potential to save patient time, money, and biologic tissue.
Typically, PBE is completed with a directly placed polymer to raise margins above the gum line, then the remainder of the tooth is restored with a crown. Research concerning PBE thus far has only tested certain polymers as an adequate direct component in PBE. Most of the polymers tested are sensitive to fluids and can be difficult to place and finish. The oral cavity is obviously full of fluids. In this study, we tested polymers have simplified handling properties and are less sensitive to fluid in the PBE technique. What type of effect would these materials have on margins and strength? RMGIC is a water-based material. Use of a water-based, hydrophilic material in the subgingival area for PBE would make logical sense in terms of biocompatibility. Research thus far makes no mention of the high fluid environment when placing hydrophobic composite during PBE.
Questions remain concerning how different polymers will compare to the typical materials used in PBE. Most notable is material long-term durability and strength under single-visit crowns. These are crowns that can be made chairside in one appointment. These unknowns steered our investigation.
- Academic Unit
- Oral Pathology, Radiology and Medicine
- Record Identifier
- 9983776752502771
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