Australian Dental Journal

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1 Australian Dental Journal The official journal of the Australian Dental Association Australian Dental Journal 2015; 60: doi: /adj The shortened dental arch concept: awareness and opinion of dentists in Victoria, Australia MA Abuzar,* AJ Humplik, N Shahim* *Melbourne Dental School, The University of Melbourne, Victoria, Australia. Royal Dental Hospital, Melbourne, Victoria, Australia. ABSTRACT Background: The occlusion of a complete dental arch is generally desirable but not necessary nor always achievable in many individuals. It is, however, relevant for dentists to consider what minimum number of teeth is required by individuals for oral function. This study investigated dentists awareness and opinion of the shortened dental arch (SDA) concept in an Australian context. Methods: A self-administered voluntary and anonymous questionnaire was mailed to a sample of 434 dentists, randomly selected from both rural and metropolitan locations in Victoria, Australia. The information collected included awareness of the SDA concept and its application as a treatment option. Results: More than half of the respondents (61%) were aware of the SDA concept. All respondents agreed or strongly agreed with the seven criteria of SDA proposed in this study based on K ayser (1989). The majority (78.4%) believed that the SDA concept is useful in clinical practice. Dentists with <20 years of experience expressed more awareness compared to others (v 2 test, p = 0.004). Conclusions: Most dentists who responded to this survey agreed that the SDA is a practical and useful treatment modality for older adults with limitations to complex restorative care. However, application of the SDA varied considerably among dentists. Keywords: Dentist awareness, older adults, oral function, patient acceptance, shortened dental arch. Abbreviations and acronyms: FPDPs = fixed partial dental prostheses; OHRQoL = oral health-related quality of life; PRDPs = partial removable dental prostheses; SDA = shortened dental arch. (Accepted for publication 15 October 2014.) INTRODUCTION The shortened dental arch (SDA) has been described as a minimum of four occlusal units which provide functional satisfaction to older adults with sufficient adaptive capacity. 1 It is a problem based treatment approach that meets the functional, biological, social and psychological needs of the older adult to an acceptable level and potentially reduces costs of treatment. 2 5 Evidence indicates older individuals with a reduced dentition of four intact premolars and one occluding pair of molars have adequate masticatory function and are able to maintain satisfactory levels of occlusal stability. 6,7 The decision to replace missing posterior teeth may depend on various factors including patient s perception of need for the prosthesis and/or diagnosis by the clinician for maintenance of oral health. The traditional approach of replacing posterior missing teeth has been with partial removable dental prostheses (PRDPs). Although benefits from PRDPs have been reported by patients with perceived impaired function, 8 optimal oral hygiene is required to maintain the remaining dentition. 9 Provision of most PRDPs appears to be driven by patients demands to satisfy aesthetics 10 and social function. 11 Subjects with a SDA have reported enhanced oral health-related quality of life (OHRQoL) from PRDPs only if missing anterior teeth were also being replaced. 12 Significant overestimations of prosthetic treatment needs have been reported if dentists rely exclusively on clinical diagnosis without incorporating psycho-social dimensions of oral health. 13,14 Further evidence indicates the SDA status as a viable long-term option whereas the SDA with PRDP intervention option was not found to be successful. 15 A large number of PRDPs are provided globally through the public and private sectors in many countries with a potential cost to health care systems, perhaps without any benefit to the patient. Unfortunately in most instances it may be Australian Dental Association

2 Dentists awareness of shortened dental arch concept a potential waste of resources if patient acceptance rates and usage of PRDPs are low. 16 Fixed dental prostheses can also be considered to replace missing posterior teeth in individuals with less than four occlusal units. Cantilever resin bonded bridges have been used satisfactorily to replace the first or second premolars to provide the four occlusal units required for a SDA. 17,18 Thomason et al. concluded that cantilever resin bonded fixed partial dental prostheses (FPDPs) were as effective as using PRDPs. 17 FPDPs have the advantage of lower caries prevalence of abutment teeth, are comfortable and acceptable to patients compared to PRDPs. 19,20 A recent investigation of FPDPs to restore a group of patients to SDA status concluded positive results regarding prognosis of abutment teeth. 21 However, these studies reviewed their study samples for up to five years only. Participants were recalled for review at different times depending on the study design and some study participants had complete dentures in the opposing arch. 20 Clinicians should be aware of the inclusion and exclusion criteria used for selection of patients in these studies and interpret results carefully prior to implementing procedures in their own clinical practice. Recent research on implant supported prostheses for restoration of posterior missing teeth show promising results. 22 Implant supported single crowns or FPDPs have the advantage of not requiring the preparation of the adjacent natural tooth. However, complications associated with implant supported prostheses such as implant loss, peri-implantitis, fracture of the prostheses and loss of bone around implants have also been reported. 23 Australia has an ageing population. However, it is projected that only about 1% of the population will be edentulous by the middle of this century. 24 Older adults are expected to retain their natural teeth in varying numbers and it is expected that there will be a large cohort of people requiring and/or requesting replacement of some missing natural teeth. With increasing availability of oral health information and improved treatment options, it is likely that this group of people will have higher expectations in relation to oral function and quality of life. The demand on health care systems, especially the public sector, would be potentially greater. While some patients may require PRDPs, suitability of alternative treatment options such as the SDA need to be considered. Although the SDA concept has been discussed considerably since its introduction by K ayser, 1 dentists awareness and application of this treatment option varies between parts of the world Data on Australian dentists awareness of the SDA concept is sparse and its acceptance by patients has not been investigated. In this context the present study aimed to: (a) assess the awareness and application of SDA by dentists in the Australian state of Victoria; and (b) investigate dentists assessment of patients level of acceptance of the SDA as a treatment option. Findings of this study could be used to manage SDA awareness among clinicians and patients. MATERIALS AND METHODS A self-administered voluntary anonymous questionnaire was mailed to a stratified random sample of general dentists in Victoria, Australia. For an adequate representation of dentists from both rural and metropolitan areas, the survey was stratified. Stratification was carried out to differentiate metropolitan and rural areas according to postcode zones using the Australian Standard Geographical Classification. 28 As there were no previous studies conducted in Australia in this context, the sample size was calculated based on the assumption that 50% of the total population of dentists registered with the Victorian Dental Board would report positive attitudes/ perceptions on the SDA concept. A sample size of 334 would be required for a p-value of 0.05 according to the formula by Dillman. 29 Based on previous studies of questionnaire surveys of Victorian dentists, the anticipated non-response rate is 30%. 30 Hence the adjusted sample size (with a 30% non-response) was estimated as 434. Postcodes were randomly selected. All dentists within the selected postcodes were included in the survey. The randomly selected postcodes were systematically followed until the required numbers of participants were achieved for both metropolitan and rural. The sample represented proportionately 78% dentists from metropolitan and 22% non-metropolitan. Questionnaires were sent out in April 2010 along with a plain language statement (PLS) explaining the aim of the study and a concise text on the SDA as a problem oriented treatment approach as follows: You are invited to assist us by completing a survey regarding the shortened dental arch concept. Whilst the science of dentistry has provided us with the means to replace missing posterior teeth through a variety of treatment options, the question still remains as to whether it is appropriate in all circumstances to replace these teeth. The quality of care, functionality, oral hygiene and comfort should be weighed against costs of ongoing care and longevity of treatment. In 1992, the World Health Organization iterated that the retention throughout life, of a functional, aesthetic natural dentition of not less than 20 teeth and not requiring recourse to prostheses should be the treatment goal for oral health care for older adults Australian Dental Association 295

3 MA Abuzar et al. The questionnaire consisted of 18 structured questions (supporting information, Appendix A). The first part of the questionnaire consisted of questions related to socio-demographic profile of dentists and their awareness of SDA. Those who answered yes to the awareness of SDA question were requested to respond to further questions regarding their practice of the SDA and the patients responses. The principles used by dentists for provision of the SDA as a treatment option was investigated using criteria adapted from K ayser 1 consisting of seven items. A second mail-out was carried out after three weeks. Ethics approval for this project was obtained from the University of Melbourne Human Ethics Advisory Committee (Ethics ID ). Statistical analysis The solicited responses to all formal structured questions were analysed using SPSS (Version 20) statistical software package. Non-parametric tests were used for the analyses. Differences were considered significant with p < Differences in the SDA awareness according to their qualifications were tested using Fisher s exact test. Awareness differences based on dentist s experience (assessed as the number of years after graduation) were tested using v 2 test. To evaluate the differences in dentists assessment of patient s responses, Kruskal Wallis H Test was used. The question on criteria for the SDA, dentists opinion of the SDA and their reasons for replacing missing posterior teeth, was structured with a 5-point Likert scale. Arithmetic mean, median and mode were calculated to interpret and qualify the overall responses. RESULTS Attributes of the responding dentists There were 175 respondents (70% males, 44% rural) which amounted to a 40.3% response rate. The majority of respondents were private general dental practitioners (86%) with a few dentists working solely in the government sector (9%). The remaining respondents were involved in both private and government or teaching. The majority of respondents (59%) have been in practice for more than 20 years; 17.1% responding dentists had a postgraduate qualification (postgraduate diploma or Master s degree e.g. DCD, MDSc). SDA awareness There were four non-respondents (out of 175) to the question How would you rate your current awareness about the SDA as proposed by K ayser (1989). Even though 61% were aware of the SDA concept, a substantial proportion (39%) was unaware of it. No significant difference was found between the awareness of those in rural (64%) and metropolitan (62%). Dentists holding postgraduate qualifications indicated more awareness than those with only the basic dental degree though the difference was not significant (Table 1). There were interesting observations in the dentists awareness and the years of experience. Participants with >20 years of clinical experience demonstrated less awareness of the SDA whereas participants with <20 years of experience demonstrated more awareness. The overall differences in awareness due to the years of experience were statistically significant (p = 0.004, Table 2). Of the aware participants, 96.1% considered application of the SDA in their clinical practice during the preceding one year and 3.9% never considered it. Those who were aware of the SDA indicated they learned the concept during undergraduate and postgraduate studies (40%), through self-education (23%) or by continuing education programmes (21%). SDA criteria and dentists opinions The question on the SDA criteria was put to all dentists in the survey irrespective of their awareness of the SDA or otherwise. For all the seven items of the criteria there was a uniform response with a median value of 4 (on a 5-point Likert scale) indicating an agreement with the criteria (Fig. 1). Most respondents (78.4%) answered in the affirmative to the question: In your opinion, does the SDA concept have a useful place in clinical practice?. Dentists opinion to the statement All missing molar teeth Table 1. Dentists awareness of SDA Highest qualification Aware % (N) Unaware % (N) Total (N) Graduate 59.3 (84) 40.7 (57) 141 Postgraduate 71.4 (21) 28.6 (09) 30 Total 61.4 (105) 38.6 (66) 171 p = (Fisher s exact test). Table 2. Dentists awareness of SDA to their years of experience Years of experience % Aware % Unaware Total (N) < > p = (v 2 test) Australian Dental Association

4 Dentists awareness of shortened dental arch concept Criteria of SDA Concept Q2,Q3 Absence of any oral pathological manifestations / craniomandibular dysfuction Sound maxillomandibular jaw relationship Other limitations to dental care (eg.accessibility, patient s mobility) Financial limitations to dental care Progressive caries and periodontal disease confined mainly to molars Good long term prognosis of anterior teeth and premolars Age of patient (>50 years) 1 Strongly Disagree Fig. 1 Dentists opinion of SDA criteria Disagree Not sure Agree Strongly Agree Dentists Opinion should be replaced in all patients was investigated on a 5-point Likert scale with an overall mean response of 1.88, indicating that the respondents disagreed with the suggestion (1 = Strongly disagree, 2 = Disagree). The reasons given by respondents, irrespective of their awareness of the SDA for replacing missing molar teeth, were mainly related to restoration of posterior teeth and improvement of masticatory function (Table 3). Dentists assessment of patients acceptability of the SDA The patients response to the suggestion of the SDA as a treatment option was assessed by those dentists who are aware of the SDA as follows: initial objection but compliance after explanation was provided (43.7%); no objections (28.2%); no opinion (19.4%); and objections (8.7%). Cost was thought as the main influencing factor for the acceptance of this treatment option by patients as reported by 63.1% of responding dentists (n = 103). The dentists assessment indicated 72% of patients were satisfied with the oral comfort and 23% thought it was sufficient. Only <6% of responding dentists reported their patients were overall dissatisfied with the treatment provided (Table 4). Few responding dentists (6%) treated about half of their 50+ year old patients with the SDA during the preceding one year (Table 5). DISCUSSION According to some recent studies, the response rate of dentists to surveys has been >70% in Victoria and higher (>80%) at a national level. 30,31 However, in Table 3. Reasons given by dentists for replacing missing first, second and/or third molars in older patients (50+ years) Reasons Responses % To restore posterior support 78.3 Prevention of anterior wear 72.6 Improve masticatory function 77.7 For patient s desire 66.3 To maintain health of TMJs 37.1 Aesthetics 25.1 Other reasons 9.1 Note: All respondents of the survey answered this question and multiple answers were recorded. Table 4. Dentists assessment of patients responses on application of SDA Patient s responses Distribution of dentists reporting on patient function (%) Chewing (n = 100) Appearance (n = 101) Oral comfort (n = 101) Unsatisfactory/ Unacceptable Sufficient Satisfactory Don t know Total % p = (Kruskal Wallis test). Table 5. Percentage of patients (50+ years) treated with SDA in the last one year Proportion of patients 50+ years % Dentists <10% % % 12 >50% 6 n = Australian Dental Association 297

5 MA Abuzar et al. this investigation, the response rate was lower than expected which may be due to the nature of the subject matter investigated. The PLS, which was provided to each participant along with the questionnaire, included a concise text on the SDA as a treatment. Though the content of PLS was meant to provide a context to the investigation, it could have been burdensome for some and possibly had an adverse effect on the response rate. This study investigated dentists opinions of the SDA criteria and their awareness in an Australian context. A large proportion of respondents (79%) in this study agreed with the SDA as a practical treatment option for older adults, which is similar to previous studies conducted in other countries, e.g. the UK 77%, 25 the Netherlands 98%, 26 and Tanzania 89%. 27 The present study consisted of a crosssectional sample of general dentists, mostly engaged in private general dental practice in Victoria, Australia, whereas the previous studies consisted of specialists and dentists at hospital health services and university dental schools About 39% of respondents were not aware of the SDA concept. This can be considered as a high proportion even though the SDA has been described as a viable treatment option in the dental literature for the past two decades. Recent graduates were more aware of the SDA concept than those who graduated 20 or more years ago (significant difference, p = 0.004). This difference may be due to Australian dental schools incorporating the SDA concept into their curricula in the last two decades. The majority of those who were aware of SDA (92%) agreed that it is a useful treatment option for the older adults. A large percentage of dentists unaware of the SDA concept were also in agreement with this treatment option. Among those dentists aware of the SDA, the frequency of application varied considerably. Most of the dentists aware of the SDA (82%) applied the concept regularly or occasionally to less than 25% of their older patients. A similar rate of application of the SDA by dentally qualified staff in restorative dentistry in Netherlands was reported by Witter et al. 26 According to the assessment of dentists in the present study, patients generally responded well to the application of the SDA as an alternative treatment once benefits were explained to them. Informed decision making by patients for management of missing posterior teeth may provide better outcomes with patient acceptance. It would also prevent over-estimation of treatment requirement with fixed or removable prostheses. Cost has been mentioned by 63% of responding dentists as a possible influencing factor for acceptance of the SDA by their patients. When posterior tooth replacement was deemed necessary by the dentists in the present study, it was mainly to restore posterior support, improve masticatory function and/or to prevent anterior tooth wear. It was not possible to discern if the respondents were referring to those patients with less than four occlusal units due to the limitation of the survey question. However, they all disagreed that all missing molar teeth should be replaced in all patients. A recent study demonstrated that fewer posterior occluding units were associated with more anterior tooth wear. 32 It is recognized that management of those older adults with extremely shortened dental arches with less than four occluding units and dissatisfied with function is a challenge. Traditionally, conventional PRDPs have been commonly used in this situation and it has remained the choice of treatment for most patients at present. Distal extension PRDPs lack retention and support distally, and often cause discomfort and dissatisfaction to patients. Torque on the mesial abutments cannot be prevented even with carefully designed PRDPs. Subject to availability of bone, this problem could be managed with a single short implant distally, to support and retain a PRDP as an overdenture. 33 Alternatively, one or two implant supported fixed crowns in the premolar region could be used to provide a minimum of four occlusal units, although the cost may be an issue to most patients. With the success rate of implant prosthodontics, the manner in which clinicians achieve a SDA has altered since it was first proposed by K ayser 1 but the concept will remain a practical and useful treatment modality for the older adult in the future. The National Oral Health Survey of Australia in 2007 reported that 11.4% of dentate adults had less than 21 teeth. 24 The year age group had 10.2 missing teeth per person which may or may not require replacement depending on patients perception, the condition of remaining dentition, cost, general health and ability to maintain good oral hygiene. Older adults with reduced dexterity and inability to perform good oral hygiene may be disadvantaged with complex fixed or PRDPs to replace missing posterior molars. It is important that clinicians are able to provide appropriate advice and practical treatment options (including the SDA) to older adults. This would involve restoration and maintenance of strategic teeth, avoidance of complex restorative treatment of posterior teeth and achieving longevity of the remaining anterior dentition. The findings of this preliminary study demonstrate that clinicians require further education regarding application of the SDA concept. The SDA treatment option is considered generally for older adults of 50+ years of age as suggested by K ayser in Presently people live longer, enjoy Australian Dental Association

6 Dentists awareness of shortened dental arch concept relatively better general and oral health, and have higher expectations from oral health services. The majority of older adults, especially in developed countries, expect to maintain good oral function even beyond years of age. Considering the changes in psycho-social dimensions of ageing and increased attention to OHRQoL by older people, it would be necessary to redefine the age of older adults to be considered suitable for the SDA status. The SDA concept should also be applicable to those patients who are medically compromised and have special needs irrespective of their age. It is desirable to extend this study to a larger sample of dentists to confirm the inferences drawn in this study. Caution is required on the findings related to patients satisfaction of function with the SDA since researchers did not solicit direct responses from the patients. Surveys designed to solicit responses directly from patients regarding acceptability of the SDA are required to confirm the initial information reported in this study. CONCLUSIONS A substantial proportion (39%) of responding dentists in Victoria, Australia, were unaware of the SDA concept. Most respondents agreed with the criteria for the SDA status and considered it a viable alternative treatment option especially for older adults. There is a need to increase the SDA awareness and acceptance among both dentists and patients in Victoria, Australia. ACKNOWLEDGEMENTS The authors would like to thank the Australian Dental Research Foundation (ADRF) for financial assistance. The authors appreciate the participants for their efforts in responding to this survey. SUPPORTING INFORMATION Additional supporting information may be found in the online version of this article: Appendix A. Questionnaire REFERENCES 1. Kayser AF. 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7 MA Abuzar et al. 24. Roberts-Thomson K, Do L. Oral health status. In: Slade GD, Spencer AJ, Roberts-Thomson KF, ed. Australia s dental generations: the National Survey of Adult Oral Health AIHW cat. no. DEN 165. Canberra: Australian Institute of Health and Welfare (Dental Statistics and Research Series No. 34), 2007: Allen PF, Witter DF, Wilson NH, Kayser AF. Shortened dental arch therapy: views of consultants in restorative dentistry in the United Kingdom. J Oral Rehabil 1996;23: Witter DJ, Allen PF, Wilson NHF, Kayser AF. Dentists attitudes to the shortened dental arch concept. J Oral Rehabil 1997;24: Sarita PTN, Witter DJ, Kreulen CM, Creugers NHJ. The shortened dental arch concept attitudes of dentists in Tanzania. Community Dent Oral Epidemiol 2003;31: Australian Bureau of Statistics. Australian Standard Geographical Classification (ASGC). Canberra: Australian Bureau of Statistics, Dillman DA. Mail and Internet Surveys: The Tailored Design Method. 2nd edn. Hoboken, New Jersey: John Wiley & Sons, Hopcraft M, McNally C, Ng C, et al. Attitudes of the Victorian oral health workforce to the employment and scope of practice of dental hygienists. Aust Dent J 2008;53: Parashos P, Morgan MV, Messer HH. Response rate and nonresponse bias in a questionnaire survey of dentists. Community Dent Oral Epidemiol 2005;33: Zhang Q, Witter DJ, Bronkhorst EM, Bartlett DW, Creugers NHJ. Occlusal tooth wear in Chinese adults with shortened dental arches. J Oral Rehabil 2014;41: Shahmiri RA, Atieh MA. Mandibular Kennedy Class I implanttooth-borne removable partial denture: a systematic review. J Oral Rehabil 2010;37: Address for correspondence: Associate Professor MA Abuzar Melbourne Dental School The University of Melbourne 720 Swanston Street Melbourne Vic maabuzar@unimelb.edu.au Australian Dental Association