Objective: The objective of this in vitro study is to compare measured values of pre-treatment tooth sizes and the Bolton overall and anterior analyses for fast-set plaster dental casts versus computer-based dental models made from a dual pour alginate impression.
Materials and Methods: Maxillary and mandibular alginate impressions were made for a sample of thirty-six patients with permanent dentitions from first molar to first molar. Impressions were poured in fast-set orthodontic plaster within one hour and allowed to set for 8-10 minutes. Casts were removed from the impressions, cleaned of any observable plaster and re-examined for quality. Impressions were packaged and sent to OrthoCAD for generation of digital models.
Measurements of mesiodistal tooth width were made using digital calipers or OrthoCAD proprietary software. Overall and anterior Bolton analyses were performed for all models. Measurements were repeated no less than two weeks later. Results were statistically analyzed for correlation coefficients and 2 x 2 MANOVA.
Results: Correlations showed very high intrarater reliability for measurements made on both plaster and digital casts. Statistical significance was found for differences between plaster and digital casts in mesiodistal measurements of maxillary and mandibular anterior segments and total arch circumference, Bolton overall ratio and Bolton anterior ratio. Values of mean difference between plaster and digital casts for the anterior segment were 0.33 mm in the maxillary arch and 0.70 mm in the mandibular arch. Mean differences over the total arch were 0.68 mm in the maxillary arch and 1.35 mm in the mandibular arch. Value of mean difference between plaster and digital casts was 0.89% for the anterior Bolton ratio and 0.80% for the overall Bolton ratio.
Conclusions: The results of this study show statistical differences for tooth size measurements between plaster casts made from the initial pour of alginate impressions and digital casts generated from the second pour. Statistical differences were also demonstrated for both the anterior Bolton ratio and total arch Bolton ratio, indicating differences between measurements were not the result of a uniform distortion occurring between the first and second pour. The small absolute value of mean differences may or may not have clinical significance. Individual practitioners should decide whether the absolute value for these small differences have clinical significance to their practice.
| Identifer | oai:union.ndltd.org:PITT/oai:PITTETD:etd-06072010-154033 |
| Date | 16 June 2010 |
| Creators | Berman, Gregory J |
| Contributors | John Close, MA, Janet Robison, PhD, DMD, Robert Robison, DMD |
| Publisher | University of Pittsburgh |
| Source Sets | University of Pittsburgh |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.library.pitt.edu/ETD/available/etd-06072010-154033/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Pittsburgh or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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