Background
Oral lichen planus (OLP) is a chronic inflammatory oral disease whose symptoms vary from a mild burning sensation to severe pain [
1]. In the OLP literature, pain perception is used as a primary measure and a proxy for patient-based outcomes [
2,
3]. Various pain measurement tools have demonstrated good correlations with the clinical severity of OLP lesions, such as the Numeric Rating Scale (NRS), McGill pain questionnaire, Visual Analogue Scale (VAS), and Change in Symptom Scale (CSS) [
3,
4]. Patient-centered approaches have used the Oral Health-related Quality of Life (OHRQoL) measures [
5]. Most studies on the OHRQoL of OLP patients used a generic measure, the Oral Health Impact Profile (OHIP), while some used a specific questionnaire designed for chronic oral mucosal diseases, the Chronic Oral Mucosal Disease Quality of Life index (COMDQ) [
4,
6‐
9]. However, the required cross-cultural adaption and validation processes limit the use of these indexes in Thailand. In our study, the Oral Impact on Daily Performances (OIDP) index was chosen because the index was developed and systematically validated in all age groups of the Thai population, i.e., primary school children, teenagers, adults, and elderly [
10‐
14]. In addition, the OIDP was used as a part of 6
th to the present (9
th) Thailand National Oral Health Surveys [
12,
15] and has been found to be a valid measure for use in many clinical trials, including patients with a prosthesis, dental implants, cleft lip and palate, and OLP [
16‐
20]. Moreover, the conceptual framework of the OIDP is different from the OHIP index because the OIDP assesses only the ultimate impacts, that are, difficulties in daily life performances which are the consequences of intermediate impacts of pain, discomfort, functional limitation and change in appearance [
11]. The OIDP considers the assessment of intermediate impacts as repetitive. However, this consequential issue is not taken into consideration of OHIP. In addition, pain measurement is already a standard patient-based outcome in OLP patients and was included as another measure in our study.
The OIDP index assesses oral impacts during the past six months on 8 daily performances and focuses on the change in behaviors in daily life, which is the ultimate impact according to its conceptual framework [
11]. The method of collecting the OIDP data is based on the frequency and the severity of the impacts on each of the eight performances, resulting in 16 answers for each patient [
11]. Therefore, some studies reduced the time-consuming data collecting procedure by using only the frequency or the severity score [
11,
21‐
27]. The OIDP frequency scale is a valid shortened version for use in Tanzania, Uganda, India, Sudan, Nigeria, Norway, and Sweden [
21‐
26]. The advantage of using the frequency score rather than the severity score is the objectivity of the patient’s answers. However, some studies considered personal feelings, although subjective, as crucial to a patient’s perceived problems. In these cases, the severity score was used [
27].
A previous study in Thai patients demonstrated that the OIDP was a valid and reliable instrument to use with OLP patients. It was well associated with the oral pain and the clinical severity of OLP, indicating the criterion and construct validity of the index, respectively [
20]. Furthermore, the OIDP differentiated between the clinical severity differences in OLP, indicating the discriminative ability of the index. However, the time-consuming interview process limits the practicality of using the OIDP. A shortened version that compromises on the comprehensive understanding of a patient’s OHRQoL, while retaining its discriminative ability would be an alternative tool for integrating the OHRQoL concept into the routine treatment of OLP patients.
The objectives of this study were, first, to assess the clinical characteristics and OHRQoL of OLP patients using the OIDP index. Second, Thai version of shortened OIDP index was developed, and its association with the original OIDP, oral pain, and the clinical severity of OLP were determined. In addition, the discriminative ability of the shortened versions was compared with that of the original version.
Results
Patient characteristics
The distribution of the patients’ characteristics is illustrated in Table
2. Out of 69 patients, ~ 80% were female. The mean age was 55.1 ± 13.9 years old (range 21–86 years old). The mean disease duration was 45.0 ± 49.6 months (range 1–264 months). Fifty out of 69 patients (72.5%) had one or more systemic conditions, whereas 19 patients (27.5%) had no systemic condition. The most common systemic disease found among the OLP patients was dyslipidemia (40.6%), followed by hypertension (39.1%) and diabetes mellitus (17.4%). About 7.2% of the OLP patients had heart diseases, thyroid diseases, or gastrointestinal diseases. Other systemic conditions were allergy (5.8%), anxiety/depression (2.9%), and 1.4% of the OLP patients had systemic lupus erythematosus, psoriasis, migraine, seborrheic dermatitis, or prostate gland disease.
Table 2
Distribution of the sociodemographic, clinical characteristics, and patient’s perception in OLP patients (N = 69)
Sociodemographic |
Sex |
Female | 55 (79.7) |
Male | 14 (20.3) |
Age | Mean ± SD: 55.1 ± 13.9 years, range 21–86 years |
Systemic conditions | No | 19 (27.5) |
Dyslipidemia | 28 (40.6) |
Hypertension | 27 (39.1) |
Diabetes mellitus | 12 (17.4) |
Heart diseases | 5 (7.2) |
Thyroid diseases | 5 (7.2) |
Gastrointestinal diseases | 5 (7.2) |
Allergy | 4 (5.8) |
Anxiety/depression | 2 (2.9) |
Systemic lupus erythematosus | 1 (1.4) |
Psoriasis | 1 (1.4) |
Migraine | 1 (1.4) |
Seborrheic dermatitis | 1 (1.4) |
Prostate gland disease | 1 (1.4) |
Clinical characteristics |
Disease duration | Mean ± SD: 45.0 ± 49.6 months, range 1–264 months |
OLP localization | Buccal mucosa | 61 (88.4) |
Tongue | 10 (14.5) |
Lip | 10 (14.5) |
Gingiva | 42 (60.9) |
Floor of the mouth | 3 (4.3) |
Soft palate | 2 (2.9) |
Number of OLP affected sidesa | 1 affected side | 5 (7.2) |
2 affected sides | 28 (40.6) |
3 affected sides | 13 (18.9) |
4 affected sides | 15 (21.7) |
5 affected sides | 4 (5.8) |
6 affected sides | 4 (5.8) |
OLP clinical severity (Thongprasom sign score) | Score 1 | 3 (4.4) |
Score 2 | 22 (31.9) |
Score 3 | 27 (39.1) |
Score 4 | 12 (17.4) |
Score 5 | 5 (7.2) |
Patient’s perception |
Pain scoreb | Presence of pain | 66 (95.6) |
Mean ± SD: 2.6 ± 2.3, range 0–8 |
Overall impact (any performance) | 67 (97.1) |
Impact on daily performances | Eating | 61 (88.4) |
Speaking | 5 (7.2) |
Cleaning | 45 (65.2) |
Sleeping and relaxing | 4 (5.8) |
Emotional stability | 43 (62.3) |
Smiling | 10 (14.5) |
Working | 6 (8.7) |
Social contact | 12 (17.4) |
The OLP clinical characteristics evaluation indicated that the buccal mucosa was the most prevalent (88.4%) affected site, followed by gingiva (60.9%), tongue and lip (14.5%), floor of the mouth (4.3%), and soft palate (2.9%). The most frequent number of OLP affected sides were two sides (40.6%), four sides (21.7%), and three sides (18.9%). The OLP clinical severity as classified by the Thongprasom sign score, based on the most severe lesion of each patient, was score 1 (4.4%), score 2 (31.9%), score 3 (39.1%), score 4 (17.4%), and score 5 (7.2%).
The pain perception results indicated that almost all of the patients (95.6%) complained of pain with a mean NRS pain score 2.6 ± 2.3 (range 0–8). The OHRQoL questionnaire revealed that the prevalence of the overall impacts of OLP to any performance was 97.1%.
Characteristics of the oral impacts on daily performances
The percentages of patients experiencing oral impacts on each of the eight daily life performances are shown in Table
2. Most OLP patients experienced difficulties on three performances, Eating, Cleaning, and Emotional stability with percentages of 88.4%, 65.2%, and 62.3%, respectively. In contrast, oral impacts on the other five performances were reported by less than 20% of OLP patients, Speaking (7.2%), Sleeping and relaxing (5.8%), Smiling (14.5%), Working (8.7%), and Social contact (17.4%).
The extent and intensity of the oral impacts are displayed in Table
3. Among the 97.1% of patients having any kind of oral impact assessed by the original OIDP index, the majority (70%) reported affected impacts on 1–3 performances, while the remaining reported oral impacts on 4 performances (15.9%), 5 performances (5.8%), and 6–7 performances (2.9%). The intensity of oral impacts results demonstrated that 33.3% had an impact at a moderate intensity, followed by 18.9% with a severe and very severe intensity, and 13% with little and very little intensity.
Table 3
The extent and intensity of oral impacts assessed by the original OIDP, OIDP-3, and OIDP-2 and their associations with oral pain and clinical Thongprasom sign score (N = 69)
Extent of oral impacts (PWI)c |
0 performance | 2 (2.9) | 2 (2.9) | 4 (5.8) |
1 performance | 16 (23.2) | 16 (23.2) | 26 (37.7) |
2 performances | 16 (23.2) | 20 (29.0) | 39 (56.5) |
3 performances | 16 (23.2) | 31 (44.9) | - |
4 performances | 11 (15.9) | - | - |
5 performances | 4 (5.8) | - | - |
6 performances | 2 (2.9) | - | - |
7 performances | 2 (2.9) | - | - |
8 performances | 0 | - | - |
Intensity of oral impacts |
No | 2 (2.9) | 2 (2.9) | 4 (5.8) |
Very little | 9 (13.0) | 9 (13.0) | 12 (17.4) |
Little | 9 (13.0) | 10 (14.5) | 9 (13.0) |
Moderate | 23 (33.3) | 21 (30.4) | 23 (33.4) |
Severe | 13 (18.9) | 15 (21.8) | 9 (13.0) |
Very severe | 13 (18.9) | 12 (17.4) | 12 (17.4) |
Correlation coefficient with OIDP | - | rs = 0.965 | rs = 0.911 |
P value | | P < 0.001 | P < 0.001 |
Paind |
Correlation coefficient | rs = 0.400 | rs = 0.372 | rs = 0.387 |
P value | P = 0.001 | P = 0.002 | P = 0.001 |
OLP clinical severityd |
Thongprasom sign score | N (%) | | | |
Score 1 | 3 (4.4) | Severe | Severe | Severe |
Score 2 | 22 (31.9) | Little‡ | Little‡ | Little‡‡ |
Score 3 | 27 (39.1) | Moderate‡‡ | Moderate‡‡ | Moderate‡‡ |
Score 4 | 12 (17.4) | Severe to Very severe‡ | Severe‡ | Severe‡ |
Score 5 | 5 (7.2) | Very severe | Very severe | Very severe |
Correlation coefficient | rs = 0.490 | rs = 0.461 | rs = 0.426 |
P value | P < 0.001 | P < 0.001 | P < 0.001 |
The results described above revealed that three performances, Eating, Cleaning, and Emotional stability, were impacted in most OLP patients. Moreover, the analysis of the extent of impacts demonstrated that most OLP patients had impacts on 1–3 daily performances. Therefore, we developed a shortened version, OIDP-3, that consisted of the 3 performances (Eating, Cleaning, and Emotional stability). In addition, a shortened version, OIDP-2 that consisted of 2 performances (Eating and Emotional stability) was developed. Cleaning was excluded from OIDP-2 because Cleaning and Eating conceptually belong to the same dimension (physical dimension), whereas Emotional stability is conceptually considered a psychological dimension. The evaluation of the homogeneity of the OIDP indicated that the standardized Cronbach’s alpha coefficient was 0.81. The corrected item-total correlations ranged from 0.24 (Working) to 0.70 (Emotional stability) (Table
4). All eight items had correlation coefficients higher than the recommended threshold of 0.2 [
32]. However, Cronbach’s alpha reduced to below the recommended threshold of 0.8 when Eating (0.74) or Emotional stability (0.73) was deleted. For the item of Cleaning, the deletion would slightly reduce Cronbach’s alpha to 0.79 which remained very close to the recommended threshold of 0.8. In addition, among the eight performances, Eating and Emotional stability had higher corrected item-total correlations compared with the others (0.66 and 0.70 respectively), while Cleaning revealed a lower corrected item-total correlation (0.44). These findings implied the importance of including Eating and Emotional stability in the index, and supported the conceptual possibility to exclude Cleaning from the index, resulting in the OIDP-2.
Table 4
Corrected item-total correlation, Cronbach’s alpha if item deleted from the OIDP index
Eating | 0.66 | 0.74 |
Speaking | 0.58 | 0.77 |
Cleaning | 0.44 | 0.79 |
Sleeping and relaxing | 0.56 | 0.76 |
Emotional stability | 0.70 | 0.73 |
Smiling | 0.51 | 0.76 |
Working | 0.24 | 0.80 |
Social contact | 0.54 | 0.77 |
Comparing OIDP-3 and OIDP-2 with the original OIDP
We calculated the extent and intensity levels of OIDP-3 and OIDP-2 (Table
3). OIDP-3 captured the 97.1% of patients having oral impacts assessed by the original OIDP. The patients who had oral impacts on more than 3 performances had impacts on Eating, Cleaning, and/or Emotional stability. Therefore, the performance of OIDP-3 in differentiating between patients with and without oral impacts was the same as that of the original OIDP. For OIDP-2, 97% of the patients having oral impacts assessed by the original OIDP were considered as having oral impacts (94.2% out of 97.1%). Thus, ~ 3% of patients with oral impacts would be excluded if OIDP-2 was used.
The OIDP-3 and OIDP-2 intensity distribution patterns were similar to that of the original OIDP. The highest proportion, approximately one-third of OLP patients, had oral impacts at the moderate level assessed by the original OIDP, OIDP-3, or OIDP-2. Comparing the proportions of patients with severe or very severe oral impacts, the 37.8% assessed by the original OIDP (18.9% with severe and 18.9% with very severe impacts) increased slightly to 39.2% when the OIDP-3 was used. However, this percentage markedly decreased to 30.4% when the OIDP-2 was used. These results implied that although very few patients with oral impacts would be excluded if OIDP-2 was used, they would consist of patients experiencing severe or very severe impacts. The overall associations between the intensity of the oral impacts assessed by the original OIDP and those of OIDP-3 and OIDP-2 were strongly significant (P < 0.001). The OIDP-3 obtained a very high correlation coefficient compared with the original OIDP (0.965), whereas, although the coefficient of OIDP-2 was slightly lower, it remained very high (0.911).
Associations between OIDP, OIDP-3, and OIDP-2 and oral pain and clinical Thongprasom sign score
The association analyses of oral pain that indicated the criterion validity of the OIDP index revealed similar results for the three OIDP versions. The original OIDP and OIDP-2 were strongly significantly associated with oral pain (r
s = 0.400,
P = 0.001 and r
s = 0.387,
P = 0.001, respectively). Whereas, OIDP-3 obtained a slightly lower significance level (r
s = 0.372,
P = 0.002) (Table
3).
The association analyses of the clinical Thongprasom sign score indicating the construct validity of the OIDP index are illustrated in Table
3. The intensity levels of the oral impacts assessed by the original OIDP increased step-wise in relation to the clinical severity of the Thongprasom sign score 2–5. The intensities of oral impacts were little, score 2; moderate, score 3; severe to very severe, score 4; and very severe, score 5. However, those assessed by OIDP-3 and OIDP-2 were almost the same as that of OIDP, except for score 4. Compared with the 1-step less clinically severe category of the Thongprasom sign score, there were significant differences in the intensity of the oral impacts assessed by the original OIDP, between score 1 and 2 (
P < 0.05), score 2 and 3 (
P < 0.01), and score 3 and 4 (
P < 0.05). There was no significant difference between score 4 and 5. This pattern was also found for OIDP-3 and OIDP-2, revealing that the 2 shortened versions had the same discriminative ability as the original OIDP. The overall association between the clinical Thongprasom sign score and intensity of oral impacts assessed by the original OIDP (r
s = 0.490,
P < 0.001) was similar to that of OIDP-3 (r
s = 0.461,
P < 0.001) and OIDP-2 (r
s = 0.426,
P < 0.001). However, three patients (4.4%) with Thongprasom sign score 1 reported a severe level of impacts, assessed by the original OIDP, OIDP-3, and OIDP-2, which was inconsistent with the pattern of positive associations between oral impacts and clinical severity.
Associations between OIDP frequency and OIDP severity and the original OIDP, oral pain, and clinical Thongprasom sign score
The other shortened versions, OIDP frequency and OIDP severity, were associated with the original OIDP as well as the oral pain and clinical severity scores (Table
5). The OIDP frequency and OIDP severity scales were strongly significantly associated with the original OIDP (
P < 0.001), however, the correlation coefficients of both versions (r
s = 0.768 and 0.880, respectively) were much lower than those of OIDP-3 and OIDP-2. Similarly, the associations with oral pain, although significant, had lower correlation coefficients and lower levels of significance (r
s = 0.354,
P = 0.003 and r
s = 0.326,
P = 0.006, respectively), compared with those of the original OIDP, OIDP-3, and OIDP-2.
Table 5
Associations between the intensity of oral impacts, the highest frequency score, and the highest severity score with oral pain and clinical Thongprasom sign score (N = 69)
Correlation coefficient with OIDP | - | rs = 0.768 | rs = 0.880 |
P value | | P < 0.001 | P < 0.001 |
Pain |
Correlation coefficient | rs = 0.400 | rs = 0.354 | rs = 0.326 |
P value | P = 0.001 | P = 0.003 | P = 0.006 |
Thongprasom sign score | N (%) | | | |
Score 1 | 3 (4.4) | Severe | 3–4 times/week | Severe |
Score 2 | 22 (31.9) | Little‡ | 1–2 times/week | Little‡ |
Score 3 | 27 (39.1) | Moderate‡‡ | 1–2 times/week | Moderate‡‡ |
Score 4 | 12 (17.4) | Severe to Very severe‡ | Every day‡ | Moderate to Severe |
Score 5 | 5 (7.2) | Very severe | Every day | Severe |
Correlation coefficient | rs = 0.490 | rs = 0.365 | rs = 0.378 |
P value | P < 0.001 | P = 0.002 | P = 0.001 |
Regarding the association with the clinical Thongprasom sign score, the medians of OIDP frequency were 3–4 times/week for Thongprasom sign score 1, 1–2 times/week for Thongprasom sign scores 2 and 3, and every day for Thongprasom sign scores 4 and 5. Although the frequency scores tended to increase with increasing clinical severity, no significant differences were detected compared with the 1-step less clinically severity score, except between score 3 and 4 (P < 0.05). For OIDP severity, the associations with Thongprasom sign scores were significant for 2 pairs, between scores 1 and 2 and scores 2 and 3. These findings indicated the lower discriminative ability of OIDP frequency and OIDP severity compared with the original OIDP, OIDP-3, and OIDP-2. The overall associations between OIDP frequency and OIDP severity and Thongprasom sign score were significant. However, the strengths of the associations and levels of significance for OIDP frequency (rs = 0.365, P = 0.002) and OIDP severity (rs = 0.378, P = 0.001) were lower than those of the original OIDP, OIDP-3, and OIDP-2.
Discussion
Generally, OIDP data are collected through individual interview questionnaires. Some versions of the OIDP were modified to be self-administered questionnaires to reduce the burden on the interviewers and time consumption [
33,
34]. Deciding on which mode of data collection would be appropriate also depends on the objective of using the index. The present study did not consider developing a self-administered version because our purpose was to develop patient-centered treatment services where the patients’ OHRQoL is taken into account. To achieve this, a positive relationship and trust between the dentist and patient are important. Patients should feel that they are respected, comfortable, and listened to about their problems. This is particularly important for older patients, including most OLP patients. Moreover, an interview elicits unarticulated thoughts, such as attitudes, feelings, and opinions, as well as patients’ desires [
35]. Thus, we believe that the individual interview mode is the strength of the original OIDP index. Keeping the mode of individual interview unchanged, we, therefore, developed shortened versions of the OIDP and investigated their qualities compared with the original OIDP.
Our findings demonstrated that OIDP-3 and OIDP-2 might be alternatives to the original OIDP in measuring OHRQoL in OLP patients. Both versions’ findings were strongly associated with the original OIDP which established a convergent validity. Moreover, they demonstrated strong associations with oral pain and the clinical severity of OLP, as did the original OIDP, which confirmed their criterion and construct validity. Moreover, the discriminative ability of OIDP-3 and OIDP-2 was also similar to that of the original OIDP. Both shortened versions differentiated between different clinical severities assessed by the Thongprasom sign scoring system. However, OIDP-2 could not capture all patients with oral impacts assessed by the original OIDP. Although very few patients (~ 3%) were excluded, some of them had experienced severe oral impacts. Deciding whether this loss is acceptable or not might depend on the available resources. In case of limited time and personnel, interviews using OIDP-3 and OIDP-2 might be considered a practical option that could provide important information on oral impacts on daily performance. However, the original version of OIDP remains recommended to comprehensively understand OLP patients’ quality of life, if there are no chair time or interviewer constraints.
The present findings were consistent with previous studies investigating patients’ perception related to their OLP and other oral mucosal lesions, i.e., Eating, Cleaning, and Emotional stability were the most three frequently affected performances [
24,
28,
36,
37]. A previous study that used the OIDP index found that Eating was the most often reported affected performance among patients with various types of oral mucosal lesions [
24]. Consistent with our results, Emotional stability was the second most frequently reported and almost equal to that of Cleaning, whereas, Working and Social contact were the least impacted [
24]. Furthermore, the highest prevalence of Eating and Emotional stability in the present study was consistent with those of an elderly Swedish population [
26]. Likewise, studies using other OHRQoL indexes demonstrated that the majority of responses to the OHIP-14 in erosive/ulcerative OLP lesions were uncomfortable to eat, presence of a painful aching, followed by feeling less satisfied with life because of their oral health [
6]. Moreover, Vilar-Villanueva et al. found that OLP patients with a worse OHRQoL gave higher OHIP scores in the dimensions of psychological discomfort and physical pain compared with the control group [
38]. As mentioned above, these findings reaffirmed that the physical and psychological dimensions were the most affected in OLP patients. Therefore, Emotional stability was supported by earlier findings in which OLP patients had higher levels of stress, anxiety, and depression compared with healthy individuals [
39‐
43]. The development of psychological change is thought to be influenced by issues regarding treatment limitations, side effects of some medications, frustration with the unpredictable nature of the lesions, and the potential for malignant transformation [
9,
44,
45]. However, it is beyond the scope of the OIDP to identify detailed psychological issues. When further psychological assessment is required, validated tools, such as the Hospital Anxiety and Depression Scale, a screening test for anxiety and depression, and the 10-item Perceived Stress Scale are recommended as suggested by Wiriyakijja et al. [
45]. Social dimension was not included in OIDP-3 and OIDP-2 because it is the consequence of the physical and psychological dimensions. Therefore, the use of only 2 dimensions, physical and psychological aspects, in OIDP-3 and OIDP-2 could be sufficient and better than a single measure, such as oral pain perception to complement OLP clinical measures and understand the patient’s problem related to OLP.
Our results demonstrated that OIDP frequency associated less strongly with oral pain and clinical severity compared with that of the original OIDP. Furthermore, OIDP frequency is unable to significantly discriminate between the clinical severities of OLP lesions. These results differ from Sulliman et al. who demonstrated the evaluative property of the OIDP frequency index of eight items [
24]. The possible reasons for the discrepancy might be attributed to differences between the participants. Sulliman et al. assessed the OHRQoL impairment in dermatological patients who had different types of oral mucosal diseases, such as oral infections, vesiculo-bullous, and ulcerative lesions, as well as benign and malignant tumors. In addition, the varying nature of the clinical course between remission and exacerbation of OLP lesions might lead to an irregular pattern of oral impacts during a six-month period. Interestingly, typically OIDP severity demonstrated similar outcomes to that of the original OIDP, however, the difference was not significant. This finding agreed with those of Amilani et al. who demonstrated the promising psychometric properties of OIDP severity among adolescents in Sri Lanka [
27]. However, the considerations for the use of a specific measure will vary depending on the specific objective. To fully assess the oral impacts on a patient’s life in a systematic way, 8 items covering all important daily performances in the physical, psychological, and social dimensions are needed. As discussed earlier, our shortened versions were purposed to be a quick tool for understanding the main oral impacts and evaluating the treatment response of OLP patients during the follow-up period.
Regarding the severity level of the oral impacts in three OLP patients with only white reticular lesions (score 1), this finding challenges the common belief that the reticular type of OLP is usually asymptomatic. This paradigm-challenging finding was supported by Adamo et al. and Vilar-Villanueva et al. in which patients with symptomatic reticular type reported higher levels of anxiety and depression compared with patients with asymptomatic reticular OLP [
38,
46]. However, this finding should be interpreted with caution due to the small sample size of the reticular OLP group. Regarding other limitations in this study, statistical regression-based approaches to determine significance could not be performed due to the small sample size. Lastly, the sensitivity to change or the responsiveness to determine the minimal clinically important difference (MID) in relation to OLP treatment cannot be assessed in a cross-sectional study. Thus, it would be interesting to evaluate its use in a longitudinal study in OLP patients. If we could follow patients with OLP after treatment and assess their oral impacts relating to OLP when their OLP has changed, we would get more understanding on the association of OLP and oral impacts relating to OLP. Further studies using a larger sample size are recommended to confirm whether reticular lesions affect patients’ OHRQoL, and whether OIDP-3 or OIDP-2 is more appropriate for evaluating OHRQoL in OLP patients. Moreover, further studies to simply the OIDP or other OHRQoL indexes for using with patients having other dental problems, such as patients with tooth loss, would be very interesting. Although a simplified shortened version might lose some qualities as compared to a full original version, its practicality would make the integration of OHRQoL concept into dental practices possible.
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