The Shortened Dental Arch Concept: Awareness, Knowledge, and Practice of Dentists in Dubai and the Northern Emirates, United Arab Emirates

Methods This is a cross-sectional study utilizing an online questionnaire anonymously to investigate the awareness and views of dentists about SDA. The questionnaire was sent to all 901 dentists registered with the Emirates Medical Association (EMA). The questionnaire consists of 17 questions, which comprise demographics, awareness, and application in dental practice, preferred treatment modality, and risks and benefits associated with SDA. The data were analyzed using SPSS Statistics. Results The response rate reported was 40.3%. Two-thirds of the respondents (65.8%) were aware of the SDA concept; however, it was not usually applied in clinical practice (n = 196, 54.7%). Specialists were more aware of the concept (p ≤ 0.001) and applied it more frequently in their clinical practice (p=0.041) than general dental practitioners (GDPs). Respondents agreed that SDA was associated with the risks of teeth migration (n = 211, 59.9%), tooth wear (n = 196, 55.8%), and/or temporomandibular disorder (TMD) (n = 163, 45.3%). The implant was the treatment of choice for many of the participants (n = 169, 46.6%) to replace missing molars, followed by the acrylic removal partial denture (RPD) (n = 129, 35.5%). Conclusions Most dentists who responded to this survey were aware of the SDA concept and had a positive attitude about it. However, they did not apply it frequently in their clinical practice.


Introduction
A normal healthy person with no developmental disorders develops a total number of 28 to 32 permanent teeth (the third molars may not always form or erupt) [1]. When several posterior teeth are missing, the dentist must take several variables into account when caring for partially dentate patients. Maintaining oral functionality, or masticatory ability, is one of the most critical elements to address, which leads dentists to wonder how many teeth are needed to suit a patient's functional needs [2]. Traditional restorative dentistry treatment planning is based on the morphological approach which suggests that in a broken-down dentition, as many teeth as technically possible should be saved or replaced. From this point of view, to meet oral functional needs, complete dental arches or at least 28 teeth were deemed necessary [3]. However, individuals' functional demands and the number of teeth required to meet them varies; hence, we should tailor our restorative care to each person's unique demands and adaptive capacity [2].
Te problem-oriented method, developed in the 1980 s by the Dutch prosthodontist Arnd Kayser, is another way to establish a treatment plan for partially dentate individuals [3]. Tis functional approach focuses on maintaining a natural, functioning, and healthy dentition with sound biological criteria to provide the patient with satisfactory function and adaptive capacity [4,5]. Te shortened dental arch (SDA) is an example of this problem-oriented approach aimed to minimize complex restorative treatments. Te SDA can be defned as "a dentition where the most posterior teeth are missing" [6].
In many cases, the replacement of all missing teeth is possible, keeping in mind the cost associated with and the real need for complete dental arches [7,8]. Since the modern diet does not require a complete and functionally intact dentition, and occlusal stability and functional requirements can be met with the presence of the anterior and bicuspid teeth, it is debated that the replacement of lost molars is not necessary unless there is a functional and/or aesthetic requirement that justifes this replacement [1,2,9]. Tis means in certain cases, replacing missing molars with cantilevers, implant-supported prosthesis, resin-bonded bridge (RBB) or distal extension removable partial denture (RPD) can be considered as overtreatment [2].
Te SDA concept focuses on providing partially dentate patients with the advantages of oral functionality, improved oral hygiene, and comfort, while avoiding overtreatment and its unnecessary costs and questionable benefts [2,10]. Te efect of SDA on patients' masticatory ability, signs, and symptoms of temporomandibular joint disorders (TMD), remaining teeth migration, oral comfort, and periodontal support has been investigated. Studies found no clinically signifcant diferences between people with SDA and those with complete dental arches regarding the abovementioned criteria [4,[10][11][12]. Tese results indicate that the classical morphological approach to restoring all missing teeth and providing the patient with complete dental arches is not scientifcally supported [11].
In 1992, the World Health Organization (WHO) stated that: "when it is not functionally or aesthetically necessary, and if occlusal disharmonies are not causing myofascial pain or problems of the temporomandibular joint, teeth should not be replaced" and "Prostheses that endanger the remaining dentition and/or supporting tissues are to be discouraged" [13]. Yet, many studies have shown that although the SDA is accepted by a great number of dentists, they do not always apply the concept in their practice [10,[14][15][16][17][18][19].
Te application of the SDA concept among dentists in the United Arab Emirates (UAE) and patients' responses to this type of treatment has not yet been investigated. Terefore, the aims of this study were as follows: (1) Evaluate the awareness of dentists about SDA concept and its application in their practice. (2) Investigate the preferred treatment modality for SDA patients and the factors that afect this decision among dentists in the UAE.

Data Collection.
A voluntary anonymous modifed questionnaire used in a previous study in Saudi Arabia by Alammari [15] was sent through emails to all dentists registered in EMA. Permission was granted by Alammari to use her validated structured questionnaire [15]. Te original questionnaire consisted of 6 demographic questions and 13 questions about SDA. Te current questionnaire was altered to contain 6 demographic and 11 questions about SDA, excluding consent-related questions, which were not counted in the total number of questions. Te diferences between the original and the current questionnaire on demographic questions were limited to replacing the questions on nationality and location of practice with questions on the country of the last academic degree taken and years of experience. Moreover, in the SDA-related section, the two original questions regarding the number of cases treated based on the SDA concept and whether dentists will lose income if SDA is implemented have been removed. Hence, modifcations were implemented to the current questionnaire, a small pilot study involving ten participants was conducted to ensure that participants understood the questions and to identify any issues with these questions. A sample size was calculated based on adopting 95% power and 5% error. A representative sample size of 542 participants was calculated for inclusion. To account for possible nonresponse, a total of 901 EMA registered dentists were included.
An e-mail explaining the aim of the study and providing brief information about the SDA concept being a problemoriented approach as described by Kayser was provided with the online questionnaire. Besides consent-related questions, the questionnaire consisted of demographic questions about gender, working sectors type, education level and specialty, years of experience, and country of last academic degree, followed by questions about dentists' knowledge of SDA, their use of the SDA concept and the treatment they typically provide to patients with pre-existing SDA conditions, the primary goal of treatment, dentists' attitude toward statements about SDA, and dentists' opinion regarding the benefts and drawbacks of SDA (supporting information, Appendix A). Te data collection took place from 9 November 2020 till 28 February 2021. Te frst e-mail was followed by a reminder e-mail after 2 weeks and a second reminder after 2 months.

Statistical Analysis. Data were analyzed using Statistical
Package for Social Sciences (SPSS) for Windows (IBM-SPSS) version 25.0 (SPSS Inc., Chicago, IL, USA). A measure of percentage was performed as descriptive statistics for categorical variables. Te data were described and analyzed in contingency and frequency tables, means and standard deviations were calculated using the independent Student's t-test for analyses of groups of dentists with respect to gender, specialty, country of last academic degree, years of experience, and dental organization. To study explanatory patterns regarding the variables (gender, type of dental practice, specialty, country of last academic degree, and years of experience) infuencing dentists' choice of treatment in an SDA and the frequency of SDA usage, a chi-square analysis was used. Tese categorical variables were cross-tabulated to examine the independency between variables. For such variables, the χ2-square test or Fisher's exact test, as appropriate, was used. A p value of less than 0.05 is considered signifcant in all statistical analyses.

Attributes of the Responding Dentists.
A total of 363 out of 901 recipients responded to the questionnaire, which accounts for a 40.3% response rate. Tere were more males (n � 239, 66.9%) among the respondents than females (n � 118, 33.1%). Te majority of the respondents were UAE graduates (n � 204, 56.2%) and 36.1% (n � 131) were international graduates. It is important to note that the questionnaire permitted nonresponses, and as a result, the total number of responses for some questions did not equal 363. Table 1 contains more information about the sample under investigation.

Awareness about SDA and Selected Mode of Treatment for
SDA. Even though two-thirds of the dentists in the survey (n = 237, 65.8%) had heard of SDA, more than half of them did not use it (54.7%) or only used it sometimes (14.2%) in their practice. Tose who preferred to replace missing molars chose implant-supported prosthesis (n = 169, 46.6%), followed by acrylic RPD (n = 129, 35.5%). Te most common reason for replacing molars was to improve mastication (n = 160, 44.3%), followed by improving both mastication and aesthetics (n = 159, 44.3%) ( Table 2). A substantial proportion (n = 123, 34.2%) of the surveyed dentists were unaware of the concept and came to know about it only when reading this survey.

Gender.
Generally, both male and female practitioners had some background knowledge of the SDA concept. However, female dentists (n � 71, 60.7%) seem to replace missing molars more frequently in their practices than male dentists do (n � 109, 45.8%) (p � 0.006). Implants were the frst choice for molar replacement for both groups, followed by acrylic RPDs.

UAE Vs Non-UAE Graduates.
A signifcant diference was detected (p � 0.010) when the application of the SDA concept in practice was compared between UAE and non-UAE graduates. Most UAE graduates did not use the SDA concept in their practice (n � 121, 59.9%), while the majority of non-UAE graduates applied it in their practice (n � 71, 54.6%).

Years of Experience.
A statistically signifcant association (p � 0.018) was found when years of clinical experience was compared with awareness of SDA. Te awareness of the concept increased with the increase in the years of experience. However, no association was found between the years of experience and applying concept in the clinical practice (p � 0.118). Most dentists with less than 3 years of experience (n � 35, 52.2%) preferred to replace missing molars with acrylic RPD, while implants were the preferred treatment option for dentists with more years of experience, (p � 0.004).

Type of Dental Practice.
A higher percentage of private sector dentists (n � 94, 58.8%) chose to replace missing molars, while dentists in the government sector preferred not to replace missing molars (n � 108, 56.0%) (p � 0.004).

Dentists' Opinions Related to Risks and Benefts of the SDA Concept.
Great variation was observed in reviewing the dentists' opinions towards the SDA concept regarding appearance, chewing function, speech, and oral comfort. Te general opinion among the participating dentists was that there were some risks associated with SDA. Most respondents stated that SDA is associated with teeth migration (n � 211, 59.9%), teeth wear (n � 196, 55.8%), and/or TMD (n � 163, 45.3%). In the evaluation of the advantages associated with SDA, there was a high agreement score for: "simplify oral hygiene," "allows for simpler treatment planning", "allows the patient to keep their own natural teeth longer" and "allows better patient economy." Specialists and GDPs from both genders agreed that SDA contributes to TMDs and teeth migration. Both also disagreed that SDA is associated with any speech problems. Similarly, the comparison between diferent years of experience with dentists' attitudes towards risks and benefts of SDA showed that as years of experience increases there is a higher agreement that SDA provides better patient economy (p � 0.04). Tere was a signifcant agreement among dentists working in the government and private sectors that SDA provides acceptable chewing function and dental appearance (p � 0.031, 0.023, respectively).

Dentists' Opinion of Criteria for Proposing the SDA Concept.
Most of the responding dentists chose to propose SDA to patients with low economic incomes (n � 207, 57.0%), followed by medically compromised and old patients (n � 157, 43.3% and n � 143, 39.4%).

Dentists' Assessment of Patients' Acceptance of the SDA Concept.
A high percentage of dentists reported that they do not propose the SDA concept to their patients (n � 165, 46.3%). Te patients' response to the suggestion of the SDA as a treatment option were assessed by the respondents as follows: agreed after an explanation was provided (38.5%); agreed immediately (7%); and objections (8.1%). A low percentage of dentists expressed that patients would agree to SDA immediately without an explanation (n � 25, 7%). Years of dental experience showed an association with the reported patient reaction towards SDA (p � 0.011). Dentists with more than 10 years of clinical experience indicated that their patients agreed to SDA as a treatment option when it was explained to them (n � 71, 48.6%), while the majority of dentists with less than 3 years or 3 to 10 years of experience did not propose SDA to their patients, 52.2% (n � 35) and 51.1% (n � 72), respectively. Although 45.8% (n � 160) of the participating dentists, whether working in private or governmental sectors, reported not proposing SDA to their patients, this percentage for private sector dentists (n � 85, 53.1%) was signifcantly higher than government dentists (n � 75, 39.7%) (p 0.006).

Discussion
Tis cross-sectional study surveyed dentists in the UAE with diferent specialties, backgrounds, and work environments to determine their understanding and application of the SDA concept in their practice.
Te 40.3% response rate was in accordance with and, in some cases, higher than the response rates of other similar studies conducted on SDA in the UK (42%) and Australia (40.3%) [14,20], however, it is considered lower than other studies conducted in KSA, Malaysia, and Jordan, which had response rates of 72.1%, 84%, and 70.7%, respectively [15,21,22]. Te low response rate could be due to the usage of an online survey distributed via e-mail, as electronic surveys have lower response rates than physical ones [23]. Te response rate may also be afected by the nature of the subject matter being investigated, since people who are uninterested in the subject are less likely to respond to the survey.
Te majority of dentists in the UAE (65.8%) were aware of the SDA concept, which is comparable to dentists' awareness in a similar study in Australia (61%) [14], but higher than another study in Saudi Arabia (34.4%) [15] and signifcantly lower than dentists' awareness in Jordan (82.1%) [21]. On the other hand, 34% of respondents were not aware of the SDA concept, which can be considered a high proportion even though the SDA has been described as a viable treatment option in the dental literature for over three decades. Furthermore, among those dentists who were aware of the SDA, the frequency of application was considerably low. Te same was found in other studies in various countries [10, 14, 16-19, 24, 25].
Dentists who had graduated from non-UAE countries were more aware of SDA and used it more frequently in their practice than UAE graduates. Tis can be attributed to the incorporation of the SDA concept in their dental school curriculums. Abu-Awwad et al. [21] reported no link between levels of education and awareness of SDA; in fact, the opposite was shown in this study, with the majority of GDPs learning about SDA only after getting the survey, whilst specialists had prior knowledge. Tis diference could be due to the fact that dental schools do not include the SDA concept in their undergraduate curricula, and the specialists are frst introduced to the concept in their postgraduate studies. Our results also showed that as the number of years of experience increased, so did the level of awareness about SDA. Tis could be related to the fact that dentists with more years of experience have learned about it through continuing education programs. Te fnding that dentists with more years of experience were more aware of SDA than dentists with fewer clinical experience contradicts the fndings of similar studies in Australia and Jordan, which found that dentists with fewer years of experience were more aware of SDA than dentists with more clinical experience [14,21]. However, despite the increase in knowledge with advanced years of experience, our study found no link between years of experience and the application of the concept in clinical practice.
GDPs reported replacing missing molars more frequently than specialists, which can be related to the lack of knowledge about SDA among GDPs in the UAE. In the present study, female dentists were more likely to select posterior tooth replacement for SDA patients than male dentists. Tis result is in agreement with a previous study conducted in Sweden [25]. Fifty percent of the participating dentists voted in favor of replacing missing molars, stating that this will improve the masticatory function and aesthetics of SDA patients. Tis outcome was in accordance with a previous study conducted in Australia [14], where 77% of participating dentists preferred to replace missing molars.
Implants were the treatment of choice for posterior teeth replacement for most of the participants, followed by acrylic RPDs. In a similar study, dentists in Jordan (84.9%) [21] agreed with UAE dentists on the implant option. Implants have become the trend for the replacement of missing teeth because of their high survival rates and the ability to provide the fxed option that is preferred by most patients [26]. However, dentists in KSA [15] and the UK [27] selected metallic RPD as the preferred treatment modality for SDA cases, while in Tanzania the majority favored using acrylic RPD for SDA cases [17]. Lack of retention and support distally in distal extension RPDs often causes discomfort and dissatisfaction to patients. When compared with RPD, implants provide better occlusal stability, simpler prostheses and more bone preservation [28]. Interestingly, the majority of dentists with less than 3 years of experience (52.2%) preferred to replace missing molars with acrylic RPD, while implants were the selected option for dentists with more years of experience. Tis could be because the provision of acrylic RPD is a simple, safe nonsurgical option and can be done by dentists with less experience, but with more clinical training and experience, dentists gradually move to implants that require more clinical skills and training.
A high percentage of GDPs preferred to replace missing molars (57.4%), while specialists mostly preferred not to (59.1%). Tis is in accordance with the fact that specialists showed better awareness of SDA than that of GDPs and, therefore, is more likely to think of SDA as a treatment option. Tis result is comparable with the results of the Abuzar study in Australia, in which the postgraduate dentists were more aware of the concept than the basic dental degree holders, though the diference was not signifcant [14].
A higher percentage of private sector dentists (n � 94, 58.8%) chose to replace missing molars, while the opposite was found in the government sector (n � 108, 56.0%). Tis can be attributed to the business elements of dental practice interfering with private dentists' decision-making on the replacement of missing molars. Most private dentists are compensated for their work through a commission-based method of payment, where a fee-per-item payment system delivers them a percentage of the fee collected from the patient. Generally, treatment in the government sector is free of charge. Tis suggests that dentists in the government sector are keen on keeping the patient's own natural teeth for longer periods of time, while the proposal of SDA can have a negative economic impact on dentists working in the private sector.
Generally, the current results showed a positive attitude towards SDA as a treatment option by the participating dentists. Dentists in this study believed that SDA provided acceptable chewing function, dental appearance, oral comfort, and speech. Tis is comparable with other studies in which dentists agreed that dental arches comprising healthy teeth up to the second premolars can serve satisfactory aesthetics, oral comfort, and function [2,11,29]. In the present study, dentists considered SDA a practical treatment option since it can simplify oral hygiene, allow for simpler treatment planning, improved patient economy as well as allowing patients to keep their natural teeth longer. Tese results are in accordance with other studies that also showed a positive attitude to the SDA concept [11,14,18,27]. Overall, participating dentists considered that there were only a few risks resulting from SDA, such as teeth migration, wear, and TMD. Although the dentists who took part in the study agreed that SDA provides satisfactory chewing function, dental appearance, oral comfort, and speech, they still consider that it is not optimal and that molars should be replaced to improve mastication and International Journal of Dentistry aesthetics. Tis is why half of the participants (n � 183, 50.8%) always replace missing molars.
A high percentage of UAE dentists did not propose SDA to their patients (n � 165, 46.3%), despite the fact that they were aware of it (n � 237, 65.8%). Tis could indicate that knowing about SDA does not necessarily imply having a thorough understanding of it, which is why most dentists did not consider recommending it to their patients. Clinicians must be able to provide patients with appropriate advice and treatment options, including SDA. Furthermore, it is generally accepted from an ethical standpoint that all treatment options, including no treatment, should be discussed with patients. Tis highlights the signifcance of continuing medical education courses and workshops to raise dentists' awareness of this ethical obligation in the UAE. Most dentists with more than 10 years of clinical experience indicated that their patients agreed to SDA as a treatment option when it was explained to them, while most dentists with fewer years of experience did not propose this option. Tis is likely because dentists with less expertise were less familiar with the concept, or young dentists were more enthusiastic about providing teeth replacement treatment.
Most of the respondents selected to propose SDA to patients with low economic incomes, followed by medically compromised patients. Patients' fnancial status played a critical role in accepting treatment with SDA as reported by 63% of dentists in a study in Australia and 45.2% of dentists in a study in Malaysia [14,30]. Tis seems sensible since providing SDA as an option can reduce the fnancial burden on the patients as well as reduce the medical risks on medically compromised patients caused by complex restorative treatments, and the subsequent needed maintenance care by both the patient and the clinician. Cost was reported as the main reason to propose SDA to patients in a similar study in Jordan [21]. After receiving sufcient explanation, approximately 38.5 percent of the participating dentists reported that their patients agreed to SDA. Tis indicates the importance of patients being well-informed and that dentists have efective communication skills.
Some clinical options, such as SDA, are more challenging than others because of controversies, search strategies, and the availability of variable recommendations, as well as the background of clinicians [31]. Generally, SDA provides a less complicated type of treatment that is also less expensive and less time-consuming. Based on the outcomes of this study, it seems that SDA is not being taught in UAE undergraduate dental universities. Its incorporation will provide a more ethical and functional way of treating patients while minimizing the risks on older and medically compromised group of patients, reducing waiting lists for prosthetic rehabilitation cases, and providing an economically positive impact by reducing the chances of overtreatment.

Limitations of the Current Study.
Although using an online questionnaire is considered a cost-efective, fast, and simple method that can cover a large group of people, it is associated with certain limitations. Tese include the inability to explain the questions to the respondents when it is not clear, as well as not being able to control who answers the questions.
In addition, only EMA-registered dentists were invited to participate, which did not necessarily include comparable representatives from various Emirates in the UAE. Terefore, the results cannot be generalized to dentists in the UAE. Lastly, the specialties included in this study include orthodontists and pediatric dentistry specialists, where one can argue that their type of work may not involve rehabilitation of SDA cases. However, in the private sector, many of the specialists are practicing restorative dental treatment along with their own specialty, and this sometimes includes treatment planning of SDA cases.

Future Studies.
Further investigations are required to study the efects of diferent treatment modalities for SDA cases on patient satisfaction and oral health. Surveying patients treated with SDA will provide an adequate level of knowledge on the level of patients' satisfaction and their oral health-related quality of life (OHRQoL).

Conclusions
Within the limitations of the present study, it can be concluded that UAE dentists are generally aware of the SDA concept and have a positive attitude about it, yet they do not usually apply it in clinical practice. Te preferred treatment modality for SDA cases are implants, followed by acrylic RPD.
Dentists in the UAE believe that SDA provides acceptable chewing function, dental appearance, oral comfort, and speech. On the other hand, participating dentists associated SDA with some risks including tooth wear, teeth migration, and TMD.
A good percentage of respondents observed that patients accepted SDA after proper explanation. Furthermore, dentists in this study believe that SDA is a good treatment option for patients with low economic status, followed by medically compromised patients. However, there is a need to increase SDA awareness and acceptance among UAE dentists and patients.

Data Availability
Te data used to support the fndings of this study are available from the corresponding author upon request.

Conflicts of Interest
Te authors declare that they have no conficts of interest. and approved the manuscript. Fatemeh Amir-Rad: conceived the concept/designed the study, performed data interpretation, wrote the original draft, and reviewed and approved the manuscript.