Christopher Wyatt

Professor

Relevant Degree Programs

 

Graduate Student Supervision

Master's Student Supervision (2010 - 2018)
In-vivo comparison of digital and conventional inter-occlusal records (2018)

Purpose: The objectives of this study were to evaluate the clinical accuracy and reproducibilityof virtual inter-occlusal records of the CEREC intraoral scanning system. The presence orabsence of inter-occlusal contacts on multiple virtual occlusal records will be compared withconventional polyvinyl siloxane (PVS) inter-occlusal records.Materials and Methods: Three conventional inter-occlusal records followed by three virtualinter-occlusal records per side per participants were taken. Then three sites of close proximity(SCP) and three sites of clearance (SC) per side per participant were identified on the transilluminatedconventional PVS inter-occlusal records. A total of sixty SCP and SC were identifiedfor ten participants using the conventional PVS inter-occlusal records. The presence or absenceof these sites were analyzed using CloudCompare Software.Result: Sensitivity for the three-different virtual inter-occlusal records was between 82% and87%. Specificity was higher with values between 93% and 97%. Positive predictive values forthe three scans were 95%, 96%, and 93%, and the negative predictive values 84%, 86% and88%. Only 74% of the SCP were detected consistently with all three repeated scans and 92% ofthe SC were identified accurately with all the three scans.Conclusion: Accuracy of CEREC Omnicam intra-oral scanner is clinically acceptable, whilereproducibility is fair.

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Virtual interocclusal registration using intra-oral scanning (2017)

Purpose: The aims of this study were to assess if virtual interocclusal records taken at different locations on the arch have an effect on the alignment of the virtual casts, and to assess whether quadrant scans and full arch scans have an effect on the alignment of the virtual casts when articulated using virtual interocclusal records. Materials and Methods: Three sites of close proximity (SCP) and three sites of clearance were identified in each sextant on mounted zirconia master models. SCP and SC were confirmed using shimstock foil and transillumination of an interocclusal impression. Full arch and quadrant scans of the master models were taken using an intra-oral scanner and different virtual interocclusal record were taken. SCP and SC on each virtual alignment produced by the intra-oral scanner were compared to each other, and to an independent software. Sensitivity, specificity, and predictive values were utilized for the comparison Results: A change in the location of the SCP was found depending on the location of the virtual interocclusal record. The intra-oral scanner software displayed contacts showed higher sensitivity and negative predictive value (92.86% and 84.21% respectively) when compared to the contacts displayed on the independent software (69.05% and 70.45% respectively). However, the intra-oral scanner software had lower specificity and PPV (41.03% and 62.90% respectively) compared to the independent software (79.49% and 78.38% respectively). Quadrant scans showed higher sensitivity when compared to full arch scans. Conclusion: There is a significant difference in occlusal contacts obtained from bite scans of different segments. This difference is more obvious in full arch scans, in which a “tilting effect” towards the site of the bite scan can be observed. Occlusal contacts obtained from bite scans taken for quadrant virtual arches exhibited higher sensitivity when compared to those obtained from bite scans taken for full virtual arches.

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The oral health-related lifestyle of Vancouver inner city elementary school-aged children (2013)

Objectives: To describe the oral health-related lifestyle of Vancouver inner city elementary school-aged children and relate different aspects of their oral health-related lifestyle with demographic and socioeconomic factors. Methods: This cross-sectional study used a structured questionnaire with some open-ended items to survey 424 school-aged children in Vancouver inner city elementary schools (53.3% boys and 46.7% girls). There were two versions of the questionnaire: the shortened version was used for grades 1-3 and included only multiple choice questions while the comprehensive version for grade 4-7 comprised both structured and open-ended questions. In the questionnaire, different items were used such as ordinal, interval and qualitative to acquire information about different aspects of oral health-related knowledge, attitudes and behaviours. Results: Overall, there was a deficiency in oral-health related knowledge and corresponding behaviours in all age groups and both genders. Thus awareness about oral health in this cohort of children needs to be improved. The oral health-related lifestyle did not differ between boys and girls except for the interdental cleaning behaviour (P=0.033). Oral health-related lifestyle did not differ according to socio-demographic characteristics except for the difference in consumption of sugar-containing drinks among age groups (P
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Exploring the views of relatives of frail elderly patients about the UBC geriatric dentistry program (2014)

Elderly residents of long-term care facilities (LTC) have difficulty accessing dental services. Aiming to improve access for this population, the Geriatric Dental Program (GDP) was established by the UBC Faculty of Dentistry in 2002. Within the GDP, elderly LTC residents receive fee-for-service dental treatment. The objective of this research is to explore whether having access to the GDP services had an impact on the life of the patients’ relatives (family members). This research hopes to better understand how quality of health in relation to dental health extends to relatives who are responsible for the frail elderly patients who receive the dental care. Such understanding will contribute to our recognition of a more holistic and widespread impact of dental care access to all segments of our society.Methods: Data was collected through semi-structured, face-to-face, audio-recorded interviews with family members of elderly patients from the UBC-GDP. A purposive criterion sampling method was used to select the family members to participate in this study. The final number of participants was determined according to saturation procedures. Interview transcription and data coding procedures were conducted following Saldaña1. All interviews were transcribed verbatim. In a second step, NVivo software was used to code and organize the transcripts into different categories to develop themes. The analysis of the data followed a qualitative, interpretive Thematic Analysis.Results: Final analysis shows that family members are worried about their relatives’ oral health; they believe that it is difficult to find private dentists with geriatric expertise and to make appointments for their family members outside of UBC, and that the UBC program helped them in fulfilling this task. Moreover, the UBC-GDP made their life less stressful and relieved the burden of setting up appointments for their relatives making their life easier. Thus, the UBC GD program positively affected the life of relatives by improving access to dental care services for the growing geriatric segment of our Canadian society. Furthermore, this study shows that the UBC GD program not only improved the perceived oral health but also impacted the relatives’ life in a positive way.

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A comparison of crown marginal fit fabricated using digital and conventional methods (2013)

Purpose. The aim of this study was to determine and compare the marginal fit of crowns fabricated using digital and conventional methods.Materials and Methods. A maxillary right second bicuspid, set in a typodont (Frasaco, Greenville, N.C., USA), was prepared for a ceramic crown. The maxillary typodont was then digitized, using a 3Shape D700 lab scanner (3Shape Inc., New Jersey, N.Y., USA) and the digital file was used to mill a replica of the maxillary arch out of a monolithic block of yttria-stabilized zirconia, to serve as master model. Digital impressions of the prepared maxillary right second bicuspid were recorded using a 3M LAVA C.O.S. scanning unit. Scan files were exported as .STL files and e-mailed to the dental lab. Files were inputed (Core3dcentres®; Las Vagas, Nevada, USA) into a digital design workflow for digital articulation, digital wax-up, and design of the final crown. Fifteen crowns were produced by 5-axis milling IPS e.max® CAD (Ivoclar Vivadent, Liechtenstein) lithium disilicate glass-ceramic blocks. An additional fifteen IPS e.max® Press (Ivoclar Vivadent, Liechtenstein) lithium disilicate glass-ceramic crowns were produced using a conventional impression and laboratory fabrication methods. The original zirconia die was removed from the zirconia master model for evaluation of crown margins. Circumferential marginal gap measurements were taken at eight measurement locations: mesial, distal, buccal, palatal, and associated line angles. The marginal gap measurements were made to determine the vertical component of marginal gap, according to the definition of marginal fit.Results. A total of 240 images (2 groups, 15 crowns per group, 8 sites per crown) were recorded and measured. The overall mean vertical gap measurement for the digitally made crowns was (48 +/- 25) μm, which was significantly smaller than that for the conventionally made ones (74 +/- 47) μm. Conclusion. The fully digital fabrication methodology provides a better fitting crown margin than the conventional methodology.

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Micro-CT measurement of the internal fit of lithium disilicate crowns (2013)

The introduction of digital impressions into the field of dentistry has begun the era of entirely computer assisted crown fabrication. The aim of this study was to assess the internal fit of lithium disilicate crowns fabricated using this novel impression technology and to compare their fit to the fit of crowns obtained by traditional elastomeric impressions. Thus, 15 lithium disilicate crowns were fabricated using an entirely digital workflow (impression and fabrication), 15 lithium disilicate crowns were fabricated manually from digital impressions, and 15 lithium disilicate crowns were fabricated using a “traditional” manual process. For the fabrication of the crowns, tooth #15 was prepared for an all-ceramic restoration on an ivorine typodont, which in turn was digitized and a replica milled in zirconia. This master zirconia model and die were then utilized for the impression procedures. Duplicate dies of the master zirconia die were made in polyurethane, enabling the internal fit of each crown to be evaluated via micro CT analysis, due to the contrast in radioopacity between the ceramic, die and internal space. The total volume of the internal space (gap), the mean and maximum thickness of the gap, and the percentage of the gap that was at or below 120um thickness were calculated and evaluated statistically via one-way ANOVA, with post-hoc Scheffé analysis. The results demonstrated that the lithium disilicate crowns fabricated from digital impressions resulted in a smaller internal space, and therefore more intimate fit, in comparison to the lithium disilicate crowns fabricated via the traditional manual approach. Three-dimensional renderings of the internal space were also created, allowing for a descriptive analysis of the distribution of this internal space.

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The oral health-related lifestyle of Vancouver inner city elementary school-aged children (2013)

Objectives: To describe the oral health-related lifestyle of Vancouver inner city elementary school-aged children and relate different aspects of their oral health-related lifestyle with demographic and socioeconomic factors. Methods: This cross-sectional study used a structured questionnaire with some open-ended items to survey 424 school-aged children in Vancouver inner city elementary schools (53.3% boys and 46.7% girls). There were two versions of the questionnaire: the shortened version was used for grades 1-3 and included only multiple choice questions while the comprehensive version for grade 4-7 comprised both structured and open-ended questions. In the questionnaire, different items were used such as ordinal, interval and qualitative to acquire information about different aspects of oral health-related knowledge, attitudes and behaviours. Results: Overall, there was a deficiency in oral-health related knowledge and corresponding behaviours in all age groups and both genders. Thus awareness about oral health in this cohort of children needs to be improved. The oral health-related lifestyle did not differ between boys and girls except for the interdental cleaning behaviour (P=0.033). Oral health-related lifestyle did not differ according to socio-demographic characteristics except for the difference in consumption of sugar-containing drinks among age groups (P
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Factors that Influence Dentists' Decitions to Treat Patients in Long-term Care (2010)

No abstract available.

 
 

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