David MacDonald

Professor

Relevant Degree Programs

Affiliations to Research Centres, Institutes & Clusters

 
 

Graduate Student Supervision

Master's Student Supervision (2010 - 2021)
Accuracy of commercially available implant planning softwares (2021)

Objectives: Cone-Beam Computed Tomography (CBCT) was first developed 29 years ago and came into commercial use in 1999 and has over the last decade been increasingly applied to almost every area of dental practice. This is due to 3D visualization of teeth and supporting tissues, high spatial resolution, low radiation, and minimal operating time compared to medical computed tomography. The CBCT images are read by an accompanying viewer or a treatment planning software. Currently, there is little information on comparing accuracy of commercially available implant planning softwares. Therefore, the aim of this study was to assess the accuracy of four popular implant planning software (coDiagnostix, DTX, Simplant, and BlueSkyPlan) by identifying the mandibular canal using the free hand nerve marking tool.Methods: Two De-fleshed human mandibles were acquired for study. Various regions of the mandibles were evaluated including canine, premolars, and molars. Gutta-percha was fixated in buccal and lingual aspects of the aforementioned regions. Mandibles were scanned in low (.30mm voxel size) and high (.18mm voxel size) resolution along with variation of mA values including 3.2, 4, and 5. DICOM files were imported into the four implant planning softwares for analysis. After image analysis, specimen were sectioned with a reverse-cutting saw in all evaluated regions. For gold standard measurements, a digital caliper was used in anatomical sections to measure comparable areas.Results: ANOVA analysis demonstrated that there is no statistical significance between the gold standard and different softwares when calculating for accuracy. When calculating for sensitivity, it appears that coDiagnostix has the highest value out of the four softwares.Conclusions: Varying mA and voxel size values does not impact the accuracy of four different softwares. It appears that coDiagnostix has the highest sensitivity values when using the most common settings for CBCT image acquisition.

View record

Dental panoramic radiograph position and preparation errors for mixed dentition patients (2021)

Objectives: To determine whether patient age or patient sex affects the number of errors on dental panoramic radiographs (DPR) in the mixed dentition population. Methods: All DPRs taken at the UBC dental student clinic, during the study period, on 6 to 12-year-old patients were examined. The consecutive case series of 178 DPRs were obtained over a 4.5-year period. The primary reviewer was calibrated on 30 DPRs. Intra- and inter- reviewer reliability was assessed upon completion by examining a random sample of 20 DPRs. A total of 14 errors were examined for on each DPR. Results: A linear regression analysis showed that the number of DRP errors decrease as the patient age increases, but with a p-value of 0.102 this is not statistically significant so we cannot conclude that age has a significant relationship with the number of errors in a DPR. A p-value of 0.44 was obtained when evaluating the difference in the average number of errors per DPR for males and females. We failed to reject the null hypothesis and did not conclude that sex had a significant relationship to the number of errors. When errors were grouped, we rejected the null hypothesis up to 0.011% significance level and concluded that age has a significant relationship to the number of errors in a DPR. Trends for head tilting left and rotating right is likely due to the DPR room design and the door location. Conclusions: Patient age and sex do not significantly affect the number of errors in a DPR in the mixed dentition population. Communication between the operator and patient likely contributes to the presence of DPR errors.

View record

Investigating the prevalence of taurodontism in an adolescent population using dental panoramic radiographs (2021)

Purpose: Taurodontism was thought to be associated mainly with oro-facial syndromes butstudies in normal Chinese and Brazilian adult populations have shown that this trait is relativelycommon. We hypothesize that taurodontism is a variation of normal root morphology that maybe present in an adolescent population as an incidental finding.Methods: Digital dental panoramic radiographs (DPRs) taken of 124 adolescents aged between15 and 20 years old (male: female; 59:65), attending the University of British Columbia’sFaculty of Dentistry Clinic between July 2006 and June 2019 were examined. Unrestored firstand second permanent molars with closed apices were measured digitally and a taurodont ratioindex was obtained using the Shifman and Chanannel criteria.Results: The total number of teeth examined was 992 and the proportion of taurodont teeth was16.6%. Of the 124 cases, 68 (54.8%) had at least one taurodont tooth. There were 43 cases withbilateral taurodont teeth. Taurodontism had a higher predilection for females (63.1%) ascompared to males (45.8%). This difference was significant for all molars with a P valueranging from P = .003 to P = .043, where P
View record

Prescriptive pattern and clinical decision making in complicated endodontic cases using cone-beam computed tomography (2017)

Purpose: Cone Beam Computed Tomography (CBCT) is an advanced but new imaging technique used in dentistry. Although it already has acquired a substantial literature, that literature does not include evidence-based evidence both for its indications-for-use and for its efficacy in comparison to the conventional approach to diagnosis and treatment planning. Aims: To determine the pattern of prescription of CBCT by all UBC dental programs with particular regard to the field-of-view (FOV). To determine whether the CBCT prescriptions by the Graduate Endodontics Program were compliant with the joint American-Academy-of-Oral-and-Maxillofacial-Radiology and American-Academy-of-Endodontics (AAOMR/AAE) position statement (viz guidelines). To determine by reference to the EPR whether CBCT changed the original diagnosis and/or treatment plans based on the initial clinical examination and the conventional radiographic.Methods: Ethics approval certificates H14-02191 and H15-03507 were granted for this retrospective study. All CBCT prescriptions were audited. The audit revealed that CBCT prescriptions by the Graduate Endodontics program were for a wide range of clinical reasons and worthy of further study. The pattern of prescription of CBCT was reviewed, by reference to electronic patient record (EPR), to determine whether it was compliant with the AAOMR/AAE guidelines. The statistical test, Chi-square was used. Results: All but one CBCT in the audit were for small and medium-sized FOVS. All 128 CBCT prescriptions (in 110 consecutive patients) were AAOMR/AAE-guidelines compliant. CBCT identified significantly more features than conventional radiography (p
View record

The use of cone beam computed tomography for implant treatment planning at UBC (2020)

Purpose: Cone beam computed tomography (CBCT) has become the standard of care for many applications in the specialty of periodontics. CBCT is now taken for almost all implant related cases and there is also a clear shift towards higher resolution images. However, the increased radiation dosage from a higher resolution images must be accompanied by valid clinical justification. Aims: The first aim was to conduct an audit of all CBCT prescriptions at the UBC Faculty of Dentistry with a focus on implant related prescriptions. Concurrently, all implant related prescriptions were evaluated for compliance with the current guidelines. The second aim was to evaluate whether altering the mA and kVp values will result in measurement differences on CBCT images. Materials and Methods: Ethics approval was granted for the retrospective portion of this study (Certificates H18-01536 and H19-02001). All CBCT prescriptions were audited from Jan. 1, 2015 to Aug. 31, 2018. However, the prescriptions originating from the Graduate Periodontics and Prosthodontics programs were examined more thoroughly. A major finding from the audit was a shift towards higher resolution images for the small FOV. An in vitro experiment was conducted to determine whether changing the imaging parameters and scatter would affect the measured distance between two adjacent implants placed in a model. Results: Almost all the CBCT scans prescribed in the Periodontics and Prosthodontics departments were prescribed for the purposes of implant treatment planning. In Graduate Periodontics and Prosthodontics, 95% and 94% of the prescriptions, respectively, were compliant with the guidelines published by the AAOMR and the AAP. Manipulation of the imaging parameters did affect the measured distance between the two implants when specific mA and kVp values were compared. The scatter and metal artifacts from the addition of a third implant did not have any effect on the measured distance.Conclusion: CBCT was used judiciously for implant treatment planning in both the Graduate Periodontics and Prosthodontics department. Manipulation of CBCT parameters had a statistically significant effect on the measured distance between two adjacent implants but the potential scatter and metal artifacts from the addition of third implant did not.

View record

The effect of the mode of reconstruction of the CBCT on the orthodontic diagnosis and treatment planning of impacted teeth (2019)

Introduction: Cone-beam computed tomography (CBCT) became commercially available 20 years ago and has been applied to almost every area of dental practice. This is due to its better spatial resolution, lower radiation dose, and smaller footprint than computed tomography (CT). However, the current CBCT unit still has much higher radiation dose than the standard conventional 2D dental imaging. Since there is no known safe lower radiation dose limit, radiation must be ‘as-low-as-reasonably-achievable’ (ALARA).Aims: To profile the orthodontic patient pool since the inception of the Orthodontics Graduate Program at UBC to determine the number and the reason for whom CBCTs were prescribed. To compare the orthodontic diagnostic efficiency of two different 3D reconstruction methods of the CBCT images. Methods: Ethics was approved for a retrospective review of orthodontic cases and for review by orthodontic instructors of randomized multiplanar reformatting (MPR) and curved CBCT image sets. 15 datasets of similar appearing impacted maxillary canines were reconstructed into MPR and curved screenshots. The instructors were asked to disclose their length of orthodontic service and prior experience reviewing CBCT datasets. They were asked to review the screenshots to determine factors that could affect treatment such as the position of the impacted canine, presence of root resorption and dilacerated roots. Results: The review revealed 35 prescribed CBCTs that were mostly taken to investigate impacted teeth (29 cases). Of the 15 orthodontists, although the 6 females had on average 16 years of experience to their 9 male colleagues (on average of 26 years), this was not significant (P = 0.142). Furthermore, they all have some experience at reviewing MPR reconstructions which was almost identical for either sex, around 6 years; 2 males and 2 females had considerably more experience. All appeared more comfortable with the MPR rather than the curved reconstructions.Conclusions: The number of prescribed CBCT images is low because the program policy follows the “Image Gently” guidelines and the ALARA principles. So far, orthodontists are more comfortable with the MPR rather than the more panoramic-like curved reconstruction. This simply may reflect the fact that the former is the default reconstruction for most CBCT units.

View record

Prescriptive pattern and clinical decision making in complicated endodontic cases using cone-beam computed tomography (2017)

Purpose: Cone Beam Computed Tomography (CBCT) is an advanced but new imaging technique used in dentistry. Although it already has acquired a substantial literature, that literature does not include evidence-based evidence both for its indications-for-use and for its efficacy in comparison to the conventional approach to diagnosis and treatment planning. Aims: To determine the pattern of prescription of CBCT by all UBC dental programs with particular regard to the field-of-view (FOV). To determine whether the CBCT prescriptions by the Graduate Endodontics Program were compliant with the joint American-Academy-of-Oral-and-Maxillofacial-Radiology and American-Academy-of-Endodontics (AAOMR/AAE) position statement (viz guidelines). To determine by reference to the EPR whether CBCT changed the original diagnosis and/or treatment plans based on the initial clinical examination and the conventional radiographic.Methods: Ethics approval certificates H14-02191 and H15-03507 were granted for this retrospective study. All CBCT prescriptions were audited. The audit revealed that CBCT prescriptions by the Graduate Endodontics program were for a wide range of clinical reasons and worthy of further study. The pattern of prescription of CBCT was reviewed, by reference to electronic patient record (EPR), to determine whether it was compliant with the AAOMR/AAE guidelines. The statistical test, Chi-square was used. Results: All but one CBCT in the audit were for small and medium-sized FOVS. All 128 CBCT prescriptions (in 110 consecutive patients) were AAOMR/AAE-guidelines compliant. CBCT identified significantly more features than conventional radiography (p
View record

 
 

If this is your researcher profile you can log in to the Faculty & Staff portal to update your details and provide recruitment preferences.

 
 

Read tips on applying, reference letters, statement of interest, reaching out to prospective supervisors, interviews and more in our Application Guide!