Implementation of a Laboratory Quality Assurance Program: The Louisville Experience Michael J. Metz, D.M.D., M.S.D., M.S., M.B.A.; Tamer Abdel-Azim, D.D.S.; Cynthia J. Miller, Ph.D.; Wei-Shao Lin, D.D.S.; Amirali ZandiNejad, D.D.S., M.Sc.; Gustavo M. Oliveira, D.D.S., M.S.; Dean Morton, B.D.S., M.S. Abstract: Remakes, or the refabrication of dental prostheses, can occur as a result of inherent inaccuracies in both clinical and laboratory procedures. Because dental schools manage large numbers of predoctoral dental students with limited familiarity and expertise as related to clinical prosthodontic techniques, it is likely these schools will experience an elevated incidence of laboratory remakes and their ramifications. The University of Louisville School of Dentistry, not unlike other dental schools, has experienced remakes associated with both fixed and removable prosthodontic procedures. Limitations in faculty standardization and variable enforcement of established preclinical protocols have been identified as variables associated with the high percentage of remakes documented. The purpose of this study was to introduce the implementation of a new multidepartmental quality assurance program designed to increase consistency and quality in both information provided to commercial dental laboratories and the prostheses returned. The program has shown to be advantageous in terms of cost-effectiveness and treatment outcomes. A statistically significant decrease in remake percentages has been recorded from inception of this program in December 2010 until December 2012. Furthermore, this program has resulted in more consistent communication between the dental school and commercial dental laboratories, among faculty members, and between faculty and students. Dr. Metz is Assistant Professor and Acting Vice-Chair, Department of General Dentistry and Oral Medicine, University of Louisville School of Dentistry; Dr. Abdel-Azim is Assistant Professor, Department of Oral Health and Rehabilitation, University of Louisville School of Dentistry; Dr. Miller is Assistant Professor, Department of Physiology and Biophysics, University of Louisville Schools of Dentistry and Medicine; Dr. Lin is Assistant Professor, Department of Oral Health and Rehabilitation, University of Louisville School of Dentistry; Dr. ZandiNejad is Assistant Professor, Department of Oral Health and Rehabilitation, University of Louisville School of Dentistry; Dr. Oliveira is Assistant Professor, Department of General Dentistry and Oral Medicine, University of Louisville School of Dentistry; and Dr. Morton is Professor and Chair, Department of Oral Health and Rehabilitation, University of Louisville School of Dentistry. Direct correspondence and requests for reprints to Dr. Michael J. Metz, Department of General Dentistry and Oral Medicine, University of Louisville School of Dentistry, 501 S. Preston Street, Louisville, KY 40202; 502-852-6168;
[email protected]. Keywords: prosthodontics, dental prostheses, laboratory remakes, quality assurance, dental education, clinical education, clinic management Submitted for publication 3/25/13; accepted 6/1/13
T
he University of Louisville School of Dentistry (ULSD) employs a comprehensive care model to provide clinical experiences to junior and senior predoctoral dental students. The dental students are assigned to one of twelve comprehensive care groups: six groups of students in their junior (D3) year and six groups of students in their senior (D4) year. A single faculty member assumes primary responsibility for the students in each comprehensive care group (as a group manager/leader) and is charged with coordinating and supervising clinical activities as well as monitoring their daily progress. Full- and part-time instructors are assigned to supervise the students as they provide patient care in the comprehensive care model. ULSD has recently established an Oral Health and Rehabilitation (OHR) clinic for the management February 2014 ■ Journal of Dental Education
of patients with more complex restorative needs. Students along with their patients are referred to the OHR clinic from the comprehensive care clinics during the treatment planning phase if the following needs exist: full mouth reconstruction, loss of vertical dimension, multi-implants, anterior/esthetic implants, and/or implant-supported removable prosthesis. The OHR clinic is staffed by full-time prosthodontists and serves as a specialty referral clinic for dental school patients to seek care with their assigned predoctoral dental students. Managing the clinical and laboratory requirements for the twelve comprehensive care groups in addition to the OHR clinic has become a challenging task. All students perform specific laboratory procedures as taught from the preclinical didactic and laboratory courses. While variation inevitably 195
occurs in the clinical environment, strict adherence to the preclinical techniques taught to the students is the cornerstone for success in patient care and also ensures a consistent educational experience. All predoctoral students are expected to complete their own laboratory work as instructed in the preclinical and clinical curricula with precision and accuracy. Contracted commercial laboratories are expected to follow laboratory authorizations as directed without approval for deviation. Of particular concern are the survey, design, master impression technique, and laboratory fabrication associated with cast removable partial prosthesis frameworks. (See Table 1 for a review of inaccuracies reported for both students/ supervising faculty and contracted commercial laboratories.) A lack of calibration in what was perceived as acceptable treatment by part-time faculty, full-time faculty, and commercial dental laboratories may be a primary factor in improving the quality of laboratorybased procedures and associated clinical treatment. A central point of contact between all clinics and the contracted dental laboratories was considered to be a key element to managing these issues. Poor communication between the clinicians and the commercial laboratories resulted in remakes that were costly to the school, laboratories, and patients in terms of treatment time, quality, and satisfaction. Therefore, a standardized protocol was developed and implemented to ensure reliable evaluation of both outgoing and incoming laboratory work, encouraging self-assessment of work quality by predoctoral dental students, the supervising faculty, and commercial dental laboratories. This laboratory quality assurance (QA) program is managed by a calibrated multidisciplinary QA team comprised of ten full-time faculty members: five general dentists with advanced restorative training from the Department of General Dentistry and Oral Medicine, and five prosthodontists from the Department of Oral Health and Rehabilitation. The laboratory QA program established the following goals actively deployed: 1) continued improvement in the quality of care provided to patients through an increase in the quality and consistency of laboratory-based clinical procedures; 2) consistent and calibrated appraisal of outgoing laboratory work to evaluate adherence to preclinical techniques, the provision of a thorough and concise work authorization, and the maintenance of quality laboratory work (casts, articulations, designs, dies, etc.); and 3) standardized evaluation of incoming laboratory work that
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would assess the compliance of dental laboratories with the work authorizations and ensure uniformity of prostheses fabricated, as well as provide calibration training for laboratories to established standards and expectations through the development of a standard operating procedure manual. A survey of dental laboratories published in 1991 identified common problems encountered by the laboratories regarding the quality of clinical and laboratory work received from clinicians for prosthetic fabrications.1 The problems identified included inadequate preparation for fixed restorations, poor impression making, and absence of rest preparations for removable partial dentures. In a more recent study,2 Christensen presented the results of a laboratory survey addressing concerns related to information provided to laboratories for prosthesis fabrication. He reported inadequate impressions, less than ideal tooth preparations, and inaccurate interocclusal records as the most common errors in fixed prosthodontics. An important finding was that up to 90 percent of final impressions for fixed prosthodontics in the United States do not accurately reproduce all of the preparation margins. This clearly identifies the outgoing laboratory work as a focus of concern regarding quality of care and accuracy. The University of Detroit Mercy School of Dentistry introduced a quality assurance program to improve the quality and consistency of clinical and laboratory work and work authorizations submitted by dental students.3 Implementation of this program resulted in a reduction in laboratory remakes over the reported three-year period. It appears that elimination of incomplete and inaccurate laboratory work authorizations, which result in compromised laboratory communication, is a major factor to be addressed in improving the consistency and quality of fixed and removable laboratory work. As reported by Lynch and Allen, limited or poorly written instructions accounted for 65 percent of remakes of porcelainfused-to-metal crowns and 25 percent of remakes for fixed dental prostheses.4 They and other researchers found that poorly written or limited instructions were responsible for more than 50 percent of cast metal removable partial prostheses framework remakes.4-6 A study by Hatzikyriakos concluded that many commercial dental laboratories do not adhere to the techniques or materials requested in dental laboratory work authorizations.7 The University of Illinois at Chicago performed an extensive overview of its predoctoral dental students to determine common
Journal of Dental Education ■ Volume 78, Number 2
Table 1. Noted laboratory quality assurance deficiencies for calendar years 2010, 2011, and 2012: 2010 is pre-QA and 2011 and 2012 are active QA University of Louisville Dental School Laboratory Quality Assurance Noted Deficiencies
Internal Remakes 2010 2011 2012
Removable Partial Dentures Inaccurate master impression/s Inadaquate rest seats Inadequate guide plans Inadequate jaw relation Poor design/ survey Unclear laboratory prescription
Removable Partial Dentures 52 10 13 14 10 7
12 3 3 4 3 2
6 2
15 3 6
10 2
8 1 2 3
4 3 2
Fixed Partial Dentures Inaccurate master impression/s Inaquate preparation/s Inadequate die fabrication Inadequate jaw relation Poor shade selection Poor material selection Unclear laboratory prescription
2 4
3 2 2 5
33 15 27 16
23 12 15 5
12 6 6 1
12 6 10 43 6 21 14
6 5 7 12 3 15 10
3 4 3 2 1 8 5
22 12
20 6
12 3
6 6 5 2 1 5
3 3 1 1
7 6 8
8 5 4
6 4 3 1
3 2 3 4
2
isregarded laboratory prescription D Inadequate margins Poor anatomical form Poor shade representation Poor final finish/polish Poor proximal contacts Poor occlusion
2 1
Complete Dentures
6 6 3 10
2 2
Implant Fixed Dentures
Inadequate wax set-up/occlusion Inadequate final process Implant Fixed Dentures
Inaccurate master impression/s Inaccurate impression technique Inadequate abutment selection Inadequate jaw relation Poor shade selection Poor material selection Unclear laboratory prescription
3 3 2
isregarded laboratory prescription D Inadequate margin placement Poor anatomical form Poor shade representation Poor final finish/polish Poor proximal contacts Poor occlusion
2 1
Implant Removable Dentures
2
Implant Removable Dentures
Inaccurate master impression/s Inaccurate impression technique Inadequate abutment selection Inadequate rest seats Inadequate guide plans Inadequate vertical dimension Inadequate jaw relation Poor shade selection Poor material selection Unclear laboratory prescription Total cases
isregarded laboratory prescription D Inadequate framework casting Inadequate wax set-up/occlusion Inadequate final process
Fixed Partial Dentures
Complete Dentures Inaccurate master impression/s Inadequate jaw relation Inadequate vertical dimension Poorly placed PPS Poor tooth selection Poor shade selection Poor base shade selection Over/under flange extension Unclear laboratory prescription
External Remakes 2010 2011 2012
1 1 1
isregarded laboratory prescription D Inadequate framework casting Inadequate wax set-up/occlusion Inadequate final process
1 2 3 1
182
91
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237
164
83
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laboratory mistakes, associated trends, and associated clinical experiences.8 That study found that senior students were more erroneous than junior students; similar errors were noted for foreign-trained students when compared to their domestically trained cohorts. The main goals of the study were to introduce a newly implemented laboratory QA program; provide an all-inclusive methodology for other dental schools to reproduce; statistically compare remake percentage data collected before the initiation of the QA review (calendar year 2010) versus active QA review (calendar year 2011); and statistically compare the progression of the active QA review process (calendar years 2011 and 2012). We hypothesized that the implementation of the laboratory QA program would significantly decrease overall remake percentages when compared to pre-QA. Additionally, we expected there would be a significant decrease in remake percentages during the active QA process in calendar years 2011 and 2012 as students and supervising faculty members were calibrated.
Methods Prior to the initiation of the laboratory quality assurance program, all contracted dental laboratories and the supervising clinical faculty participated in a day-long calibration training symposium held by the QA faculty at the University of Louisville School of Dentistry. Each discipline coordinator presented a short seminar on his or her preclinical techniques in order to educate all parties to the expected standard of care. Of particular emphasis were removable partial denture metal framework design and fabrication. The symposium awarded the commercial laboratories the opportunity to bid for thirty-six-month contracts with the university and provided crucial faculty calibration. A series of initial calibration sessions were held among the QA faculty to gauge agreement and scoring of laboratory cases. Case review was random and helped to establish agreement among the review group to the documented standards posted in preclinical course manuals. Of particular importance was the continued reproducibility of scoring among the QA review faculty members. A consistent reproducibility was achieved by the QA group prior to the implementation of the laboratory quality assurance program. The quality assurance protocol at ULSD begins with dental students submitting completed laboratory work required for individual fixed and removable procedures. All work is submitted to a
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central collection point (Figure 1). In addition to the required laboratory procedures, students are required to submit completed laboratory work authorizations in accordance with the guidelines in the preclinical course manuals for the corresponding disciplines and in compliance with the requirements of Commonwealth of Kentucky laws. The laboratory work is provided with a unique identifier, entered into tracking software (Microsoft Access 2010; PROSTRAX) as incoming or outgoing by the dispensary staff, and cleared for evaluation by the QA team. The quality assurance team is comprised of ten full-time faculty members from two departments, all of whom have advanced training in restorative and prosthetic dentistry. Two faculty members (one from each department) are assigned for each daily QA session and are charged with the review of outgoing and incoming laboratory work. Laboratory work to be reviewed is equally divided and randomly assigned to each faculty member. Fixed, removable, and implant laboratory procedures are evaluated for acceptable execution from protocols in the preclinical and clinical curriculum. All evaluations follow a standardized review form with an established checklist (available from corresponding author), for which the student must obtain 100 percent satisfaction (all acceptable check marks). For outgoing laboratory work, each reviewer determines if the published criteria required of laboratory work for the treatment being performed have been met. If so, the QA faculty member releases the work to the commercial laboratory for fabrication. If the QA faculty member identifies a deviation from the published protocol, the work is returned to the student and/or group manager with specific feedback for modification and resubmission. The corrected laboratory work is returned to the original QA reviewer who identified the problem for approval. The corrections are evaluated to confirm that each conforms to the published protocols, and the work is processed by the dispensary staff and released to the commercial laboratory. Any disagreements with QA decisions are encouraged to be resolved by the covering clinical faculty member, individual group manager, and involved QA reviewer. Final authority and conflict resolution rest with the director of laboratory QA. For incoming laboratory work (Figure 2), a similar process is followed. For each day, one of the two assigned faculty members randomly evaluates the returned work according to protocols provided and determines if it is likely to be clinically acceptable. If deemed to meet the criteria of 100 percent
Journal of Dental Education ■ Volume 78, Number 2
Figure 1. Laboratory quality assurance cycle: cases leaving for commercial laboratory
Figure 2. Laboratory quality assurance cycle: cases returning from commercial laboratory
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(all acceptable check marks) on the ULSD laboratory QA form, the case information is updated, entered into the tracking software, and released to the student for patient evaluation and delivery. In the event that quality standards are not met (checked unacceptable), the work is returned to the commercial dental laboratory with a clear explanation of the concerns along with an acceptable method for resolution. All cases involving corrections are outlined on a review form created for communication of clinical and laboratory concerns or issues (form is available from the corresponding author). The form lists the most common inadequacies encountered at the time of prostheses insertion (occlusion, shade, etc.), so that issues occurring subsequent to the QA process may also be tracked. In such instances, the supervising faculty member marks the appropriate box corresponding to the issue encountered, and the relevant data are collected. The time required for commercial laboratories to complete the requested work is posted for the students and supervising faculty member to review. They are instructed to become familiar with the posted times and observe them in addition to the required QA processing time (one to two days) when scheduling patients. This strictly enforced protocol has improved communication among all involved parties and has resulted in more efficient utilization of clinic time and a reduction in potential patient inconvenience. Individual cases are monitored by the tracking software via data entry by staff members to ensure appropriate progression of each laboratory case. The tracking software utilized is Microsoft Access (PROSTRAX) software program (Microsoft Corp., Redmond, WA) that tracks the procedure being performed, student, patient, and commercial dental laboratory. All remakes performed, internal (school faulted) or external (commercial laboratory faulted), are categorized by reason for remake (open crown margin, inadequate RPD design/retention, inadequate denture set-up, etc.). The raw data output yields monthly reports of overall case numbers, remakes per group, remakes per laboratory, and percentages for each. The percentage of remakes associated with both internal and external causes are closely monitored and reported. Thirty-six months of data were chosen (calendar years 2010, 2011, and 2012) to evaluate twelve months of pre-QA implementation (2010) against twenty-four months (2011, 2012) of active QA.
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Statistical analyses were performed using Origin software version 8.1 (OriginLab, Northampton, MA) to compare total remake percentages comparing twelve months of pre-QA (2010) against twenty-four months of active QA (2011, 2012) and to compare the progression of the first twelve months of active QA (2011) against the second twelve months (2012). Data were presented as the means ± standard deviations. Significant differences were determined by one-way analysis of variance (ANOVA) followed by Tukey HSD post-hoc t-tests, and significance was defined as p
