Implant-retained prostheses have demonstrated

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1 Training Needs for General Dentistry Residents to Place and Restore Two-Implant-Retained Mandibular Overdentures Hans Malmstrom, DDS; Jin Xiao, DDS, MS, PhD; Georgios E. Romanos, DDS, PhD; Yan-Fang Ren, DDS, PhD, MPH Abstract: Implant therapy is rapidly becoming a standard of care for replacing missing dentition. Predoctoral dental curricula include some training in the implant restorative phase but offer limited exposure to the surgical phase, so it is important for postdoctoral general dentistry residency programs to provide competency training in all phases of implant therapy. The aim of this study was to determine the training needed for general dentistry residents to achieve competence in this area, specifically by defining the number of clinical experiences necessary in both the surgical and prosthetic phases of implant-retained mandibular overdenture construction (IRMOD). Fifteen Advanced Education in General Dentistry (AEGD) residents at one academic dental institution placed two implants in a total of 50 patients with edentulous mandibles and subsequently restored them with IRMOD. The supervising faculty member and the residents evaluated the competency level on a five-point scale after each implant placement and prosthetic case completion. According to the faculty evaluations, the residents achieved surgical competence after placing two implants in four to six cases and prosthetic management competence after restoring two to four cases of IRMOD. All 50 patients were satisfied with the treatment outcomes of IRMOD. This study concluded that general dentistry residents could potentially achieve competence in both the surgical and prosthetic phases of implant therapy while enrolled in an AEGD program. Dr. Malmstrom is Director, Division of General Dentistry, Eastman Institute for Oral Health, University of Rochester; Dr. Xiao is Assistant Professor, Eastman Institute for Oral Health, University of Rochester; Dr. Romanos is Professor, School of Dental Medicine, Stony Brook University; and Dr. Ren is Professor, Eastman Institute for Oral Health, University of Rochester. Direct correspondence to Dr. Hans Malmstrom, Eastman Institute for Oral Health, University of Rochester, 625 Elmwood Ave., Rochester, NY 14618; hans_malmstrom@urmc.rochester.edu. Keywords: postdoctoral general dentistry, general dentistry residents, advanced dental education, clinical research, implantology, dental implants, mandibular overdenture Submitted for publication 4/7/14; accepted 6/23/14 Implant-retained prostheses have demonstrated remarkable predictability and long-term success due to recent advances in osseointegration technologies. These prostheses have also been shown to provide better functional outcomes and improved quality of life when compared with conventional prostheses. 1 These factors have encouraged dental practitioners and patients to adopt implant-retained prostheses as preferred options for replacing missing dentition. 1 Dental schools worldwide have also recognized such trends and broadened their training curricula in implant therapy. 2 The Commission on Dental Accreditation (CODA) has updated its standards for dental education programs and is now mandating that U.S. dental school graduates must be competent, within the scope of general dentistry, in providing dental implant prosthetic therapies for their patients. 3 As a result of these factors, dental schools in the United States have strengthened their implant dentistry curricula. However, the scope of training in implant therapy at the predoctoral level is often limited to the prosthetic phase and includes diagnosis, treatment planning, and prosthetic management of single implants or implant-retained overdentures. 4,5 Although some dental schools include the surgical phase of implant therapy in their curricula, commonly this opportunity is offered to only a small, selective group of students. 6,7 The current European consensus on implant dentistry in university education states that the fundamental principles of implant dentistry should be taught in the predoctoral curriculum; however, surgical placement of implants should not be expected at this stage but rather should be comprehensively delivered at the postgraduate level. 8 For all these reasons, it is clear that most dental school graduates need additional training in the surgical placement of implants and prosthetic management before they can competently provide this service to their patients. Many dental school 72 Journal of Dental Education Volume 79, Number 1

2 graduates in the United States choose to complete a one- or two-year Advanced Education in General Dentistry (AEGD) or General Practice Residency (GPR) program before going into practice. CODA standards require that AEGD and GPR programs offer training in dental implant therapy. The objective is to have such training programs include both surgical and prosthetic phases of implant therapy in their curricula. Currently, there is a lack of information on the training needs for general dentistry residents to achieve competence in both surgical and prosthetic phases of implant therapy. A significant number of mandibular complete denture wearers have difficulty adapting to this treatment modality due to poor retention and psychological factors The McGill and York consensus recommended that a two-implant-retained mandibular overdenture (IRMOD) should be the first choice for edentulous patients. 12,13 A study in the United States substantiated that recommendation and suggested that IRMOD education should be offered to dental students and dentists. 14 IRMOD is an ideal model for trainees to master both the surgical and prosthetic skills of implant therapy, and recent studies indicate that novice general dentists and students in U.S. and European dental schools can be trained to provide the prosthetic management of IRMOD with outcomes comparable to those of experienced practitioners Until now, there have been no studies investigating whether trainees could achieve an acceptable level of competence in both implant surgical placement and prosthetic management in a postdoctoral general dentistry program. The aims of this study were therefore to evaluate the number of clinical experiences and the didactic and hands-on training needed for AEGD residents to achieve competence in both the surgical and prosthetic phases of IRMOD and to assess the feasibility of implant training in the context of a postdoctoral general dentistry residency program. Methods This study was approved by the research subject review board at the University of Rochester, and informed consent was obtained from each participant at enrollment. Fifteen AEGD residents with no previous experience in placing and restoring dental implants with overdentures volunteered to enroll in the study. The supervising faculty member and the AEGD residents evaluated the competency level after each implant placement and prosthetic reconstruction. A total of 50 adult subjects who had recently received mandibular complete dentures but were dissatisfied with the outcome were also enrolled in the study. At baseline, all these subjects were asked to evaluate their prosthesis for retention, comfort, speech, overall satisfaction, and other health-related quality of life issues using a Visual Analog Score (VAS) scale. 18,19 If they were not satisfied, the denture was relined, and the subjects were reevaluated six weeks later using the same evaluation questionnaire. If satisfaction was still not achieved, AEGD residents under direct supervision of a general dentistry faculty member placed two dental implants in the anterior mandible between the mental foramina. Three to four months after implant placement, the residents placed overdentures on the two implants. To determine success, the bone loss, mobility, gingival index, pocket depth, and plaque index were measured, and the patients were asked to complete a questionnaire regarding satisfaction with the prosthesis at two-week, three-month, one-year, and two-year follow-up visits. Selection of Residents and Patients Novice AEGD residents meeting the following criteria were included: 1) having no previous experience in dental implant placement and restoration; 2) agreeing to limit their clinical experience in placing and restoring dental implants to this study until study completion; 3) being able to understand and respond to questionnaires used in the study; and 4) being willing to accept the protocol and provide consent. As the length required for completion of the study was not clear, only the first-year residents in a two-year AEGD program were selected to ensure study completion. Besides direct supervision during the surgical and restorative procedures, the residents also received the following training. They first participated in a didactic course in basic dental implantology that included principles of placement and restoration of dental implants. This course was followed by handson training in both the surgical and prosthetic phases using the selected implant system on an artificial mandible, hands-on training in placing ten implants in pig jaws using the selected implant system, and clinical observation of five cases, each with two dental implants between the mental foramina and an IRMOD restoration. January 2015 Journal of Dental Education 73

3 Inclusion criteria were also defined for the patients to participate in the study. Each patient was evaluated by a general dentistry resident and a faculty member to ensure that he or she met these criteria: 1) 18 years of age and older with an edentulous mandible; 2) dissatisfaction with a mandibular complete denture that was recently made and relined; 3) ability to understand and respond to questionnaires used in the study; 4) willingness to give consent; and 5) in generally good health. Patients who met the following exclusion criteria were not allowed to participate: insufficient bone to place two implants between the mental foramina of the mandible, being severely immunocompromised or pregnant, or having psychological or psychiatric conditions that could influence treatment. Treatment Procedures and Evaluation All surgeries were performed by AEGD residents under the direct supervision of an experienced general dentistry faculty member who had extensive training and more than 25 years experience in placing and restoring dental implants and who was involved in the training and implementation of competency-based curricula in postdoctoral general dentistry. The surgical and prosthetic procedures have been described in detail elsewhere. 20 Briefly, a surgical guide was fabricated on study casts by duplicating the existing mandibular complete denture. A midcrestal incision was made, and a full thickness flap was raised. Two Zimmer tapered screw-vent implants (Zimmer Dental Inc., Carlsbad, CA, USA) (3.75 mm diameter; 10 mm, 11.5 mm, or 13 mm length) were placed in the intraforaminal area in either the canine or the lateral incisor locations. All implants were placed in a crestal position. A healing abutment was placed, and interrupted sutures were used to achieve primary closure. Immediately following implant placement, panoramic and periapical radiographs were taken. Three to four months after implant placement, the original dentures were connected to the two implants using locator attachments (Zimmer Dental Inc.) (tapered screw-vent 3.5 mm D, 0-3 mm cuff). Medium force locator male attachments (pink) (Zimmer Dental Inc.) were chosen for the overdenture delivery appointment. The supervising faculty member and the AEGD residents evaluated the competency level after each implant placement and prosthetic reconstruction. Both the residents self-evaluation and the faculty evaluation of resident competence were based on a five-point novice-to-expert scale according to Chambers 21 using the Dreyfus model 22,23 (Table 1). The competent level in this model is defined by having good background and working knowledge of placing and restoring IRMOD, the ability to achieve most tasks without faculty input, the ability to cope with complex situations through logical analysis and planning, using the experience as a basis for future tasks, and judging the outcomes as successful but needing further refinement. This level of competence is viewed as the beginning of the independent practice of the procedure. 21 Clinical competence was evaluated in regard to surgical and restorative phases of IRMOD including treatment planning, patient assessment, radiographic evaluation, surgical skill, suture skill, knowledge of the implant system, and overdenture construction. Implant success was assessed using a combination of criteria defined by Albrektsson et al., 24 adapted by others, and reported in our previous publication. 20 In brief, the surgical phase of the IRMOD was considered successful if there was absence of mobility, absence of persistent subjective complaints (pain, foreign body sensation, and/or dysesthesia), absence of recurrent peri-implant infection with suppuration, absence of a continuous radiolucency around the implant, no pocket probing depth 5 mm, and no bleeding on probing. During the first year, 1.5 mm of vertical bone resorption was accepted, and after the first year of insertion, the annual vertical bone loss should not exceed 0.2 mm. 24,29 Patient satisfaction was evaluated at two weeks, three months, 12 months, and 24 months after overdenture delivery and was based on the following three criteria: prosthesis retention, chewing function, and speech ability. Rating of each category was based on a 100 mm VAS scale from 0 mm representing extremely difficult or not at all satisfied to 100 mm representing not at all difficult or extremely satisfied. The higher the score, the better the prosthesis as perceived by the patient. The non-parametric Kruskal-Wallis test was used to compare data between time points at two weeks, three months, 12 months, and 24 months after IRMOD delivery. When significant differences were detected, pairwise comparisons were made between the groups using a Wilcoxon signed-rank test. The chosen level of significance for all statistical tests was p<0.05. Statistical computation was performed using SPSS 12.0 software (SPSS Inc., Chicago, IL, USA). 74 Journal of Dental Education Volume 79, Number 1

4 Table 1. Novice to expert determination and evaluation scale Level Knowledge Standard of Work Autonomy Coping with Complexity Perception of Context Novice Minimal, or textbook knowledge without connecting it to practice Unlikely to be satisfied unless closely supervised Needs close supervision or instruction Little or no conception of dealing with complexity Tends to see actions in isolation Beginner Basic working knowledge of key aspects of practice Straightforward tasks likely to be completed to an acceptable standard Able to achieve some steps using own judgment, but supervision needed for overall task Appreciates complex situations but only able to achieve partial resolution Sees actions as a series of steps Competent Good working and background knowledge of area of practice Fit for purpose, though may lack refinement Able to achieve most tasks using own judgment Copes with complex situations through deliberate analysis and planning Sees actions at least partly in terms of longer term goals Proficient Depth of understanding of discipline and area of practice Fully acceptable standard achieved routinely Able to take full responsibility for own work (and that of others where applicable) Deals with complex situations holistically; decision making more confident Sees overall picture and how individual actions fit within it Expert Authoritative knowledge of discipline and deep tacit understanding across area of practice Excellence achieved with relative ease Able to take responsibility for going beyond existing standards and creating own interpretations Holistic grasp of complex situations; moves between intuitive and analytical approaches with ease Sees overall picture and alternative approaches; vision of what may be possible Note: Scale is modified from the professional standards for conservation, Institute of Conservation (London) 2003 based on the Dreyfus model of skill acquisition. Results All fifteen AEGD residents completed the study and reached the competent level in both the surgical and prosthetic phases of IRMOD during their residency training period. A total of 100 implants were placed in 50 subjects. Of these, two implants were lost in one subject, and one subject died during the follow-up period for reasons unrelated to the study. The 48 remaining subjects had their implants restored with overdentures by the residents. The implant success rate was 97.8% at the two-year follow-up visit. The number of surgical cases needed for the AEGD residents to achieve competence in placing mandibular intraforaminal implants is shown in Figure 1. Evaluations by the faculty member were compared with those by the residents themselves. In general, the faculty member was more conservative in rating the surgical competency level than were the residents. According to the faculty evaluation, 56% of the residents were rated as novice and 44% were rated as beginner after the first surgery; 22% were novice and 78% were beginner after the second sur- gery; and 100% had reached the beginner level after the third surgery. In the faculty member s evaluation, 11% of the residents reached the level of competent after the fourth surgery, 75% reached this level after the fifth surgery, and 100% were rated as competent after the sixth surgery, having each placed a total of 12 implants. In their self-evaluation, the residents tended to rate themselves at a higher level than the faculty evaluation after each surgery, and all the residents rated themselves as competent after the fourth surgery, having each placed a total of eight implants. The number of clinical cases needed for the AEGD residents to achieve competence in overdenture construction and delivery is shown in Figure 2. Again, the faculty member was more conservative in rating the prosthetic competency level than were the residents. According to the faculty evaluation, 29% of the residents were rated as novice and 71% as beginner after the first IRMOD delivery. After delivery of the second IRMOD, the faculty member rated 71% of the residents as competent. This number increased to 75% after the third IRMOD delivery and reached 100% after the fourth delivery. The residents tended to rate themselves at a higher level than the January 2015 Journal of Dental Education 75

5 Figure 1. Residents (n=15) and faculty member s assessment of training needed for achieving competence in surgical phase of mandibular intraforaminal implant placement Figure 2. Residents (n=15) and faculty member s assessment of training needed for achieving competence in restorative phase of two-implant-supported overdenture restoration faculty evaluation after each IRMOD delivery, and all the residents rated themselves as competent after the third delivery. Figure 3 shows the cases needed for 100% of the AEGD residents to achieve specific surgical and restorative technical proficiency related to IRMOD fabrication competence as evaluated by the supervising faculty member. In the faculty evaluation, 100% of the residents achieved competence in the fabrication of surgical guides after completion of two cases. Achieving competence in abutment locator selection and fitting required at least three cases. After four cases, 100% of the residents achieved competence regarding knowledge of implant components, instruments/instrumentation/equipment, suturing techniques, and overdenture abutment pick-up and delivery techniques. Treatment planning/ patient evaluation/radiograph assessment and soft 76 Journal of Dental Education Volume 79, Number 1

6 Figure 3. Number of cases needed for 100% of the residents to achieve competence as evaluated by supervising faculty member tissue management competence was achieved after five cases. Competence in implant placement was achieved by 100% of the residents after six surgeries. As compared to the other aspects of the technique, this area required the most experience. The patients satisfaction with retention, speech, and the ability to bite and chew hard food with their mandibular dentures improved significantly (p<0.05) after the dentures were attached to the dental implants (Figure 4). The patients rated their satisfaction in denture retention as 27.6 at baseline on the VAS scale; this level increased nominally to 32.7 after denture reline, but reached 76.7 two weeks after IRMOD delivery and remained high at around 80 during the 24-month follow-up period (Figure 4, panel A). Similarly, the patients satisfaction in chewing ability was rated as 26.7 at baseline, increased to 38.5 after denture reline, reached 74.8 two weeks after IRMOD delivery, and remained high at about 80 during follow-up (Figure 4, panel B). The patients satisfaction in speech was rated as 43.1 at baseline, increased to 48.9 after denture reline, rose to 81.5 two weeks after IRMOD delivery, and remained high at about 80 during the follow-up (Figure 4, panel C). Discussion The findings of this study indicate that a novice general dentist in a general dentistry residency program could be successfully trained to place implants in edentulous mandibles and restore them with IRMOD. The success rate of implants placed by the AEGD residents was 97.8% in a 24-month period, which is comparable to studies in which the implants were placed by experienced practitioners. 1,18,19 The patients satisfaction in chewing, retention, and speech for the IRMOD was very good and remained high at the 24-month follow-up. This study found that novice general dentists may reach a competent level in implant surgery after placing eight to 12 implants in four to six cases when supervised by an experienced general dentistry faculty member. Competence in the prosthetic phase of IRMOD was achieved earlier than competence in the surgical phase as a majority of the residents needed only two to four prosthetic cases as compared to four to six surgical cases. There were disagreements between the faculty member and residents regarding the number of clinical exposures needed to achieve competence, a finding that should be further evaluated. In our AEGD program, the IRMOD curriculum was carefully designed to include didactic courses in basic dental implantology and hands-on training using an artificial mandible for the surgical and prosthetic phases of the procedure. This training also includes direct supervision and instruction by an experienced clinician during implant placement and overdenture fabrication. The evaluation of resident performance in this study was modified from the Chambers competency-based dental education concept 30 and the Dreyfus model. 22,23 Competence is the midpoint on the continuum of professional growth from novice to expert. 21 Competence is defined as the performance supported by understanding and appropriate professional values necessary to begin the independent practice of dentistry and to assume responsibility for completing one s professional growth. Competence is a transitional stage and not an end-point. 30 January 2015 Journal of Dental Education 77

7 Figure 4. Patients satisfaction regarding two-implant-supported mandibular overdentures (n=48) *Statistically significant at p<0.05 Researchers and professional organizations have been defining competency standards for dentistry in the United States for about 20 years; however, this study is the first to use the novice-expert system to evaluate the training necessary for novice AEGD residents to achieve competence in placing implants and restoring them with IRMOD, thus providing valuable data on implant therapy from an educational point of view. The findings suggest that, considering the high demands and patient availability for this service, it should be feasible to include implant surgery as part of one- or two-year AEGD or GPR programs. These program settings provide a learning environment conducive to enhancing residents surgical and restorative experiences as the advice and support provided to them are greater than that available to most dentists in a general practice setting. Further studies are warranted to explore the training needed to achieve competence in implant therapy with IRMOD in other educational settings or in private practice. IRMOD appears to be an ideal model for assessing surgical and prosthetic competence in implant therapy for general dentistry residents. The surgical aspect requires that operators have the basic skills to make a crestal incision, raise buccal and lingual full-thickness flaps, protect vital structures, prepare implant sites for receiving implants at acceptable inclinations, place the implants with parallelism, assess primary stability, and suture the flaps. These 78 Journal of Dental Education Volume 79, Number 1

8 basic competency skills are essential for a novice operator to acquire in a controlled educational setting before becoming an independent practitioner. For the prosthetic aspect, the general dentistry residents are required to first fabricate a conventional complete mandibular denture; assess the stability, retention, and patient satisfaction of the conventional denture; and then provide the option of IRMOD to patients who are dissatisfied with the outcome, further modify the complete denture, and manage its transition to IRMOD if the patient elects the option. These are competency skills that are essential in general dentistry practices. A limitation of this study is that the competency evaluation was performed by one faculty member. Although it could be argued that two calibrated evaluators would be preferable in the study design and would make the data more statistically significant, it would be difficult to have two available faculty members to view the entire surgical and restorative procedure and rate each resident s performance during the two-year study period. Another limitation is that the study was conducted at one academic dental institution with one group of residents, so the results may not be generalizable to all AEGD residents and programs. Conclusion The results of this study suggest that general dentistry residents can potentially achieve competence in both the surgical and the prosthetic phases of implant therapy while enrolled in an AEGD program. This study should add valuable information for incorporating dental implant education into pre- and postdoctoral general dentistry curricula. Acknowledgments The study and related implant materials were supported by a grant from Zimmer Dental Inc., Carlsbad, CA, USA. We also gratefully acknowledge Dr. Michael Alan Yunker for critical reading and language revision of the manuscript. REFERENCES 1. Thomason JM, Lund JP, Chehade A, Feine JS. Patient satisfaction with mandibular implant overdentures and conventional dentures 6 months after delivery. Int J Prosthodont 2003;16: Kido H, Yamamoto K, Kakura K, et al. Students opinion of a predoctoral implant training program. J Dent Educ 2009;73(11): Commission on Dental Accreditation. Accreditation standards for dental education programs. Chicago: American Dental Association, Afsharzand Z, Lim MVC, Rashedi B, Petropoulos VC. Predoctoral implant dentistry curriculum survey: European dental schools. Eur J Dent Educ 2005;9: Petropoulos VC, Arbree NS, Tarnow D, et al. Teaching implant dentistry in the predoctoral curriculum: a report from the ADEA implant workshop s survey of deans. 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