Swati Ahuja

Fracture strength of CAD/CAM composite and composite-ceramic occlusal veneers.

PURPOSEnTo determine the effect of material type and restoration thickness on the fracture strength of posterior occlusal veneers made from computer-milled composite (Paradigm MZ100) and composite-ceramic (Lava Ultimate) materials.nnnMETHODSn60 maxillary molars were prepared and restored with CAD/CAM occlusal veneer restorations fabricated from either Paradigm MZ100 or Lava Ultimate blocks at minimal occlusal thicknesses of 0.3, 0.6, and 1.0mm. Restorations were adhesively bonded and subjected to vertical compressive loading. The maximum force at fracture and mode of failure were recorded. 2-Way ANOVA was used to identify any statistically significant relationships between fracture strength and material type or thickness. Spearmans rank correlation coefficient was used to analyze mode of failure with regard to fracture strength.nnnRESULTSnThe average maximum loads (N) at fracture for the Paradigm MZ100 groups were 1620 ± 433, 1830 ± 501, and 2027 ± 704 for the material thicknesses of 0.3, 0.6, and 1.0mm, respectively. The Lava Ultimate groups fractured at slightly higher loads (N) of 2078 ± 605, 2141 ± 473, and 2115 ± 462 at the respective 0.3, 0.6, and 1.0mm thickness. Statistical analyses revealed that, while no significant difference existed among the various restoration thicknesses in terms of fracture strength (P>0.05), the material type was found to be influential (P=0.04). The maximum load at fracture (N) for Lava Ultimate averaged over all thicknesses (2111 ± 500) was significantly higher than that of the Paradigm MZ100 (1826 ± 564). No correlation between mode of failure and fracture strength was found.nnnCONCLUSIONSnUnder the conditions of this study, the maximal loads at fracture for these non-ceramic occlusal veneer restorations were found to be higher than human masticatory forces. Occlusal veneers made from the two materials tested are likely to survive occlusal forces regardless of restoration thickness, with those fabricated from the composite-ceramic hybrid material being more likely to survive heavier loads.

Classification and management of restorative space in edentulous implant overdenture patients

A classification system of available vertical restorative space (from the crest of the soft tissue edentulous ridge to the proposed occlusal plane) is introduced for edentulous arches to be restored with implant overdentures. The Class I arch has available vertical restorative space equal to or greater than 15 mm. An arch with 12 to 14 mm of available vertical restorative space is categorized as Class II. Class III represents an arch with 9 to 11 mm of available space, while an arch with less than 9 mm of vertical restorative space is categorized as Class IV. A review of clinical procedures designed to improve vertical space availability is provided, including alveoloplasty, intentional increase of occlusal vertical dimension, occlusal plane repositioning and management of overdenture attachment selection. The authors stress the importance of considering vertical restorative space and its management for implant overdenture patients during treatment planning prior to implant placement.

Defining available restorative space for implant overdentures

It is important to diagnostically evaluate available restorative space prior to implant placement. Failure to accurately assess restorative space may result in esthetically and structurally compromised prostheses and patient dissatisfaction. This article describes various techniques for evaluating restorative space in edentulous patients. Information gained will help dentists during treatment planning, attachment selection, and prosthesis design prior to surgical implant placement.

Comparison of polymerization shrinkage of pattern resins

STATEMENT OF PROBLEMnThe dimensional stability, in particular polymerization shrinkage, of pattern resins affects the accuracy of implant prosthesis fabrication. Recently introduced photopolymerizing pattern resins are easy to use, but their shrinkage needs to be determined and compared with traditional autopolymerizing pattern resins.nnnPURPOSEnThe purpose of the study was to compare the polymerization shrinkage of photopolymerizing pattern resins with autopolymerizing pattern resins.nnnMATERIAL AND METHODSnTwo autopolymerizing (DuraLay, GC Pattern resin) and 2 photopolymerizing (Primopattern LC Gel, Primopattern LC Paste) pattern resins were tested. The sample size was 10 for each group. Polymerization shrinkage was determined by measuring the change in area dimensions with image analysis. The percentage of volumetric shrinkage was calculated, and the results were statistically analyzed with ANOVA, followed by the Student-Newman-Keuls post hoc test (α=.05).nnnRESULTSnThe volumetric shrinkage values (%; mean ± standard deviation) for Duralay were [corrected] 5.72 ± 0.89; for GC pattern resin, [corrected] 5.07 ± 1.36; for Primopattern LC Gel, 5.42 ± 1.83; and for Primopattern LC Paste, 7.43 ± 0.62. The volumetric shrinkage of the Primopattern LC Paste was significantly higher than that of the other 3 materials.nnnCONCLUSIONSnThe photopolymerizing pattern resin in gel form (Primopattern LC Gel) had a similar shrinkage value to the autopolymerizing pattern resins (DuraLay and GC Pattern Resin). However, the photopolymerizing pattern resin in paste form (Primopattern LC Paste) shrank significantly more than the other 3 materials tested.

Accuracy and reliability of stitched cone-beam computed tomography images

Purpose This study was performed to evaluate the linear distance accuracy and reliability of stitched small field of view (FOV) cone-beam computed tomography (CBCT) reconstructed images for the fabrication of implant surgical guides. Materials and Methods Three gutta percha points were fixed on the inferior border of a cadaveric mandible to serve as control reference points. Ten additional gutta percha points, representing fiduciary markers, were scattered on the buccal and lingual cortices at the level of the proposed complete denture flange. A digital caliper was used to measure the distance between the reference points and fiduciary markers, which represented the anatomic linear dimension. The mandible was scanned using small FOV CBCT, and the images were then reconstructed and stitched using the manufacturers imaging software. The same measurements were then taken with the CBCT software. Results The anatomic linear dimension measurements and stitched small FOV CBCT measurements were statistically evaluated for linear accuracy. The mean difference between the anatomic linear dimension measurements and the stitched small FOV CBCT measurements was found to be 0.34 mm with a 95% confidence interval of +0.24 - +0.44 mm and a mean standard deviation of 0.30 mm. The difference between the control and the stitched small FOV CBCT measurements was insignificant within the parameters defined by this study. Conclusion The proven accuracy of stitched small FOV CBCT data sets may allow image-guided fabrication of implant surgical stents from such data sets.

Defining the posterior palatal seal on a definitive impression for a maxillary complete denture by using a nonfluid wax addition technique

The posterior palatal seal area is defined as the soft tissue area at or beyond the junction of the hard and soft palates on which pressure within physiologic limits can be applied by a removable complete denture to aid in its retention. The retention of the maxillary denture is affected by the extent and the design of the posterior palatal seal. This article discusses a method of defining the posterior palatal seal on a definitive impression for a maxillary complete denture by using microabrasion and a nonfluid wax addition technique.

Fabricating a Mandibular Implant Supported Overdenture with a Suspended Framework

The introduction of implant-supported overdentures as a clinical alternative has improved the quality of life of the edentulous population. Implant-supported overdentures have diminished many of the problems associated with conventional dentures by providing improved retention, stability, function, esthetics and physical and emotional health. Greater support and stability of the implant borne prosthesis is associated with improved bite force and oral function for overdentures when compared to conventional complete dentures. An adequate amount of restorative space is required when fabricating implant-supported overdentures. This space must accommodate a denture base of sufficient dimensions, appropriately positioned denture teeth, and an implant attachment system. Insufficient space may lead to reduced structural integrity of the prosthesis and/or compromised oral function. Typically a mandibular removable prosthesis is more vulnerable to fracture due to its shape and overall dimensions. Incorporation of a metal framework, metal reinforcing mesh, or woven or fiberglass-impregnated mesh have been recommended to improve resistance to denture fracture during function. This article presents a method for fabricating a framework that is specifically and predictably suspended within the denture base in order to decrease fracture susceptibility of implant-supported overdentures.

Diagnosis and treatment of orofacial pain in a patient with unserviceable complete dentures: A clinical report

An ill-fitting complete denture has the potential to create pain and discomfort as well as conceal or confound the diagnosis of other primary sources of orofacial pain such as trigeminal neuralgia. Guidelines of the American Academy of Orofacial Pain offer an evidence-based approach for the assessment, diagnosis, and management of orofacial pain. A complete and accurate differential diagnosis is paramount to the success of treatment as well as to the circumvention of unnecessary therapy. The purpose of this clinical report was to emphasize an evidence-based approach to the diagnosis and treatment of orofacial pain in a patient with edentulism and a history of prolonged denture wear.

Fabrication of new restorations with a consideration of oral hygiene.

Maintenance of adequate and effective oral hygiene is crucial for the long-term success of any dental therapy. This article discusses a case that failed due to the poor oral hygiene of the patient. Fabrication of uncomplicated restorations, patient education, motivation, maintenance and recall are important factors to be considered when treatment planning patients with poor oral hygiene.

Managing maxillary proclination with novel designed angulated implants

Implant-supported removable dental prostheses may be supported by a variety of splinted (bar and clip) attachment systems or nonsplinted abutment-based attachments (ball, magnets, and resilient stud attachments such as locators [Zest Anchors], ERA [Sterngold], and nonresilient-stud attachments such as ANKYLOS SynCone [Dentsply Implants]). Nonsplinted attachments are preferred as they are more economical, less technique sensitive, easier to clean, repair, and maintain than splinted (bar and clip) attachment systems, but they work favorably only when implants in the arch are placed parallel to each other. Often implants in the anterior maxilla have to be placed with a labial inclination (due to the proclination of the premaxilla), resulting in lack of parallelism between the anterior and posterior implants, making it challenging to fabricate a removable dental prostheses supported by nonsplinted attachments, and necessitating the use of angled abutments. Recently, a novel implant design with a 12° restorative platform angulation has been introduced by Southern Implants (Co-axis, Keystone Dental, Inc., Burlington, MA, USA). These new angulated implants aid in minimizing the divergence between the anterior and posterior maxillary implants without using angled abutments. The purpose of this article was to report a case utilizing the novel angulated implants (Co-axis, Keystone Dental, Inc., Burlington, MA, USA) in the premaxilla for fabrication of maxillary removable dental prostheses supported and retained by nonsplinted attachments.