Psychometric properties of the Albanian version of the Orofacial Esthetic Scale: OES-ALB

A sample of 169 subjects, aged from 19 to 86 years participated in this study. The study was approved by the Ethics Committee of the University Dentistry Clinical Center of Kosovo. The written consent was obtained from each subject after explanation of the aim of the study. The sample was divided into three groups. One convenience group comprised prosthodontics patients (PP, n = 57) with no treatment need. They had prosthetic restorations not older than one year and were satisfied. Twenty-seven of them had fixed partial dentures (FPD’s) and 30 had removable dentures (RD’s). The second convenience group included prosthodontics patients with treatment need (PPTN, n = 51), they came to a dental office asking for treatment. A specialist of prosthodontics assessed that 31 patients needed FPD’s and 20 patients needed RD’s. The two sample groups (PP and PPTN) were selected at the Department of Prosthodontics, School of Dental Medicine, University of Prishtina and Private Dental Clinic GS, Prishtina in Kosovo. The third consecutive group comprised of dental students (DS, n = 61) with natural teeth, without any need for dental treatment, and without orthodontic or dentofacial anomalies (malocclusion, anomalies of jaw size, jaw relationship, dental arch relationship, tooth position, etc.).

The OES English language version was translated into the Albanian language according to the conventional methodology, following the procedure already used in previous adaptation and validation studies in other countries [31‐33].

The English version with 8 items was translated by a qualified translator, with excellent knowledge of dental vocabulary. For the translation of some expressions in the Albanian language, three other dentists with excellent proficiency in the English language were also included. The translated version was edited by two other dentists, with excellent comprehension of English language (Dental School, Faculty of Medicine, University of Prishtina). The translation was done individually and in the end the final editing was integrated into the definitive one. Further, the final version was back-translated into the English language by an independent qualified translator, together with three other dentists with excellent comprehension of English language. The final version, translated back to the English language, was evaluated independently by one native English language speaker and two professors from the Dental School, University of Zagreb, with excellent expertise in English. They confirmed that there was no significant differences from the back translated and the original version. The final translation was considered to be satisfactory for its further use.

Prior to this study, the clarity of the OES in the Albanian language was tested in 30 prosthodontic patients (age range 27–63 years) who were not involved in the study. Feedback regarding any problems of understanding and answering the questionnaire was obtained and addressed. Consequently for avoiding misunderstanding of overall face aesthetic, as face wrinkles, shape of nose or eyes, as the OES has been designed exclusively for assessing the esthetics of the lower third of the face and teeth, the items “Your facial appearance” and “Appearance of your facial profile” were slightly revised and specified as “Appearance of the lower third of your face” and “Appearance of the lower third of your facial profile”. The original OES version utilized the 11 point rating scale (10 = very satisfied and 0 = very dissatisfied) [28]. As suggested in the Croatian study [31], the Likert 5 point scale (1 = unsatisfactory; 5 = excellent), and also applied in the Chinese OES version [32] was used in this study because of the traditional evaluation in primary and secondary schools in Kosovo uses the 5 point scale (1 = unsatisfactory; 5 = excellent). The first seven items face frontally, profile, mouth (lips, visible of teeth, smile line), tooth position, tooth form, tooth color and gum indicate to exclusive esthetic components and scores of these first seven items can comply to form an OES summary score. The last eighth item appraises respondents general satisfaction with their esthetic and together with other first seven components can be combined to form an OES total summary score. The lower scores characterized dissatisfaction with orofacial esthetics and in contrary, higher scores represented higher satisfaction. Besides the OES questionnaire items, the subjects also answered three questions from the Albanian version of the OHIP-49 questionnaire which were related to esthetics (questions number 3, 22 and 31) [35]. The PP and PPTN groups were interviewed and the DS group self-administered the OES questionnaire but, they were supervised by three dentists.

The reliability (internal consistency and test-retest), validity (construct, convergent, discriminative) and responsiveness of the OES-ALB were assessed.

Two categories of reliability were measured; the internal consistency and test–retest reliability (the consistency of the scores through a reasonable period of time). The internal consistency was tested by using the average inter-item correlation and Cronbach’s alpha coefficient [37]. Average inter-item correlation should be more than 0.40. According to guidelines, Cronbach’s alpha values > 0.75 correspond to excellent outcome, values from 0.40 to 0.75 are considered satisfactory and the value of < 0.40 are considered as poor outcome [37]. Test–retest reliability was assessed as temporal stability, which was tested by calculating the interclass correlation coefficient (ICC) using the one-way analysis of variance [38]. The test-retest reliability was performed only in the group of Dental Students, who filled-in the OES questionnaire twice within a period of 14 days between trials. Participants did not receive any dental or oral treatment during the observed period. The values of ICC <0.40 indicated poor interclass correlation, 0.41- 0.60 moderate, 0.61 – 0.80 good and the values > 0.80 indicated excellent interclass correlation [38].

The construct, convergent, and discriminative validities were tested [39]. All participants were included. The exploratory factor analysis (EFA) was used for assessing the number of factors of the OES-Alb. The Kaiser-Mayer-Olkin (KMO) test, Bartlett’s test of sphericity and the scree plot were used [40, 41]. The eigenvalue above 1 was set as criteria for factor with a drawl; also significant factor loadings > 0.30 were defined. The convergent validity was tested by Spearman’s rank correlation between a self-reported general satisfaction with orofacial esthetics and the OES summary score. It was also tested by the Spearman’s rank correlation between the OES summary score and the sum of three questions from the OHIP-ALB49 related to esthetics (items 3, 22 and 31) [35]. Discriminative validity assumes that unrelated measures are in reality not related. It was predicted that dental students without orofacial anomalies would have better esthetics than prosthodontics patients with a treatment need. The discriminative validity was tested by comparing the OES total summary score between the three sample groups (PP, PPTN, and DS) using the one-way analysis of variance and the Sheffe post-hoc tests.

It was tested in 51 prosthodontic patients with treatment requirements [42]. They completed the questionnaire twice; prior to treatment and a month later after they had received new dentures. Thirty-one of them received fixed partial dentures (FPDs) and twenty of them received removable denture (RDs). A month period was considered sufficient for adaptation to new dentures and new esthetical appearance. The difference of the OES total summary scores between the baseline and the follow-up was tested using the paired t-test and by calculating the effect size and the standardized response mean [43]. According to Cohen the effect size of > 0.80 is considered large, 0.50 moderate and 0.20 small [44]. The standardized effect size was determined using the formula [44]:

Statistical analyzes were computed using MS Excel (Microsoft Office, Windows 2007, USA) and SPSS 19 for Windows (SPSS Inc., Chicago, Illinois, USA) software.