Tooth surface loss (TSL) is a progressive phenomenon, arising from erosion, abrasion, attrition or abfraction. It may present as a normal physiological process occurring throughout life  (e.g. attrition) or as a gradual progressive pathologic process. It has a multifactorial cause and is rarely seen in isolation . It can affect individuals of any age group: children, young adult, adults or the elderly . The prevalence of TSL varies around the world. In Nigeria, a prevalence of 53% was reported by Ibiyemi et al.  among rural dwellers in the southwest region of the Country while a study in Trinidad, West Indies by Rufeek et al.,  reported a prevalence of 72% and a study among elderly population in Iraq  reported 100% prevalence.
The health of individual tooth or the entire dentition can be compromised by tooth surface loss with manifestations ranging from dentine hypersensitivity to severe loss of tooth structure, abnormal occlusion and reduced facial height . At the early stage of development, patients with tooth wear lesion may have no symptom, but if left untreated, it brings discomfort especially during eating, drinking or tooth brushing and this may progress to spontaneous pain or the pulp may become necrotic . The patients seek help because of problems of pain, altered function and unsatisfactory appearance especially when the anterior teeth are involved .
The management of patients with TSL has caused great challenges for dental professionals for many years and the problem is on the increase due to the fact that more of the population is retaining their natural teeth into old age . It was therefore the aim of this study to determine the patterns of tooth surface loss among adult patients who presented at the conservation unit of the Dental Centre of a Nigerian University Teaching Hospital and to assess the effects of tooth wear lesions on their quality of life.
2. Material and Method
The participants for this cross-sectional study were drawn from patients attending conservation clinic of the Dental Centre, in a Nigerian teaching Hospital. A convenience sampling method was adopted for the study. All consecutive patients that presented at the clinic with TSL during a period of one year (April 2017 to April 2018) and were willing to participate were recruited. After obtaining consent, the patients were assessed and examined clinically and those that satisfied the inclusion criteria were recruited into the study. The inclusion criteria were: willingness to participate, mental wellbeing and presence of TSL on any tooth. A self-administered questionnaire (Appendix 1) was used to obtain information from the participants. The questionnaire consisted of two parts. The first part asked about patients’ age, gender, occupation, types of TSL and teeth affected. Patients were classified into five occupational groups using the modified classification of socio-economic strata devised by Famuyiwa et al.;  Class 1 included executive managers, bankers, large scale business men; Class 2: senior civil servants, Nurses, University and Polytechnic lecturers; Class 3: semi-skilled workers like artisans, junior civil servants; Class 4: unskilled workers, retiree and house wives, and class 5: students and the unemployed. The second part asked about the effect of TSL on oral health related quality of life using Oral Health Impact Profile-14 (OHIP-14) questionnaire. The OHIP-14 questionnaires consist of 14 questions subdivided into seven domains: functional limitations, physical discomfort, psychological discomfort, physical disabilities, psychological disabilities, social disabilities, and handicaps. For each question on the OHIP-14, the subjects were asked how frequently they had experienced the problem during the preceding 12 months. Responses were recorded using a 5-point Likert scale: 0 = never, 1 = hardly ever, 2 = occasionally, 3 = fairly often and 4 = very often. Total OHIP score was calculated for each subject by adding the score for each question, while the mean score was calculated by dividing the total score by fourteen. The prevalence, extent and severity of oral health impact were calculated as suggested by Slade et al. . Prevalence is the percentage of respondents reporting 1 or more “fairly often” or “very often.” This variable identifies those whose oral health impacts are chronic rather than transitory; Extent is the number of items reported “fairly often” or “very often.” while severity is the sum of the response codes for the 14 items (Total OHIP scores). The severity score can range from 0 to 56, higher values indicating more frequent impacts. The OHIP questionnaire has been validated and found reliable in our environment (Lawal et al.) .
Oral examination was carried out in the dental clinic using probe and dental mirror with gloved hands by a calibrated senior resident doctor that was appointed for data collection. Prior to the recruitment of the patients and data collection, the criteria for categorizing the type of TSL into attrition, abrasion, erosion and abfraction were set out for him using the guidelines of Kelleher and Bishop .
Data were analyzed using IBM Statistical package for the social sciences (SPSS) version 20. Descriptive statistics, such as percentages, means and standard deviations, were used to describe basic information including sex, age, marital status, education level, occupation and type of tooth wear lesion. Chi-square test was employed to assess relationship between the outcome variable (total OHIP-14 scores) and socio demographic variables and types of tooth wear lesion. A p-value < 0.05 was considered significant.
Table 1 shows the socio-demographic characteristic of the patients. One hundred and twenty-five patients participated in the study. There were 72 (57.6%) males and 53 (42.4%) females. The age range was 15 to 90 years with a mean of 52.58 (17.84 S. D) years. The majority 54, (43.2%) were in the age range 41 - 60 and 61 - 80 years and 40 (32%) of the respondents were low income earners, while 35 (28%) were executive officers.
The most common type of tooth surface loss presented was attrition (40%) followed by abrasion (23.2%) while the least common was abfraction 6% (Figure 1).
Table 1. Socio-demographic characteristic of the patients.
Figure 1. Distribution of types of tooth surface loss.
Table 2 shows the distribution of the items on OHIP with fairly often and very often responses. Fairly or very often responses by the patients were recorded for all items of the OHIP questions. However, painful sensation had the highest impact, 39 (31.2%) patients in which 22 (17.6%) and 17 (13.6%) patients reported very often and fairly often respectively to the question: “Have you had painful aching anywhere in your mouth?” This was followed by problem with chewing 26 (20.8%) in which 11 (8.8%) and 15 (12%) patients stated very often and fairly often respectively to the question “Have you had difficulty chewing any food because of problem with your teeth?” while the least impact, 1 (0.8%) was for inability to perform usual function with the response very often 0 (0%) and fairly often 1 (0.8%) to the question “Have you been unable to perform the usual functions because of problems with your teeth?”
The severity of impact of TSL on quality of life of the patients ranged from 0 to 34 with a mean of 11.65 (SD = 6.27), while the extent ranged from 0 to 7 and the prevalence of impact i.e. percentage of respondent reporting fairly often or very often for one or more items was 57.6%, (Table 3).
Table 2. Distribution of item on OHIP questionnaire with very/fairly often responses.
On domain mostly affected by TSL, physical pain domain had the highest mean, 3.10 ± 1.52 followed by functional limitation 2.14 ± 1.50 and the domain least affected was handicap domain with a mean score of 0.97 ± 1.36 (Table 4).
Table 5 shows the relationship between gender and total OHIP score: Higher proportion of females (47.2%) when compare with males (44.4%) had total OHIP score above the population mean. However, the relationship between patients’ gender and impact of TSL on quality of life was not statistically significant (p = 0.452). Also, the relationship between patients’ ages and impact of TSL on quality of life was not statistically significant (p = 0.763), though higher percentage (53.3%) of patients in age group 20 - 40 years had total OHIP scores that
Table 3. Distribution of severity and extent of impact of TSL on quality of life of patients.
*The severity of impact range from 0 to 34 with a mean of 11.65 (std = 6.27). *Seventy-one (56.8%) had one or more items with very/fairly often responses given a prevalence of impact of 56.8%.
Table 4. Distribution of OHIP scores according to domains.
Table 5. Relationship between demographic variables and severity of impact of TSL on quality of life.
were above the population mean.
Table 6 shows the relationship between type of TSL and total OHIP score: Greatest proportion of patients with erosion (53.3%) had total OHIP scores above the mean (greater severity of impact) while the least proportion 6.7%, were patients with abfraction. However, the relationship between types of TSL and severity of impact on quality of life was not statistically significant (p = 0.534).
TSL is a complex biological process with varying etiological factors. Various types have been identified which includes attrition, abrasion, erosion and abfraction . Attrition is tooth wear resulting from tooth to tooth contact and is more prevalence in population where the diet has greater abrasive components and also in individual with parafunctional habits such as grinding and clenching habits . Abrasion is tooth wear due to frequent contact of tooth surface with other hard substances such as hard tooth brushes, and abuse of dental scaling. Erosion is tooth surface loss resulting from biochemical action. It is more prevalent among people with gastric reflux, vomiting and high consumption of gastric juice .
Previous studies ,  reported differences in the incidence of TSL in relation to the genders of the participants. In this study, the incidence of TSL is higher among male (57.6%) than female. This is similar to the findings of Oginni and Olusile  that TSL is more prevalent among males in Nigeria. The reason for this could be that males are more involved in habits that result in tooth wear lesions such as clenching and grinding of teeth and also the possibility of males having higher bite forces than females .
This study also reveals that TSL affects individuals in all age groups but the prevalence is higher among middle age and the elderly. This is in agreement with the findings of higher incidence of TSL in the older age group by Ibiyemi et al.  and Taiwo et al., . This is however, contrary to Rubby  report that it was more prevalent among patients less than 26 years old. The difference in
Table 6. Relationship between types of TSL and severity of impact on quality of life (total OHIP scores).
the prevalence in relation to age in Rubby and our study could be due to dissimilarity in the predominant type of TSL in the two studies. Attrition which increases in prevalence with increase in age because of the cumulative effect of teeth contact was more prevalent in our study while erosion was predominant in Rubby’s study .
The most common type of tooth surface loss presented in this study was attrition (40%) and this is similar to result of previous studies in Nigeria  . This is however, contrary to report of a study in Saudi-Arabia  and a European’s study  in which erosion accounted for 90% and 70% of tooth surface loss respectively. The disparity in the findings could be due to differences in the main etiological factors of TSL in different part of the world. In this environment, the dietary habits of crushing bone, taking fibrous food and the use of chewing stick for oral hygiene care was a common practice  and this can be the reason for the predominant attrition type of TSL in this study.
Our findings show the prevalence of impact to be 57.6% and the highest impact of TSL (39) was on painful sensation followed by problem with chewing. Daly et al.  also reported painful sensation and discomfort as the most common negative effect of TSL on the quality of life of their patients. However, Bardsley  reported problem with aesthetic as most impact of TSL on quality of life of the population studied. Painful sensation was responsible for the highest impact on OHQL in this study possibly because of the poor dental awareness of the patients leading to late presentation in the clinic for treatment.
There was a greater impact of tooth surface loss among females than males and this could be due to the fact that females are more concerned about their oral health than males . Also a higher proportion (53.3%) of the patients in age group 20 - 40 years (young adult) had total OHIP score above the population mean indicating greater severity of impact of TSL in this age group than other. This might be explained that people in this age group are more critical about their quality of life, more concern with respect to their appearance and oral functions and less tolerant to changes in their dental status.
In this study, the domain least affected was handicap domain (which asks about patient’s inability to perform usual functions and found life less satisfying because of TSL). This finding agreed with report of previous study that common dental diseases although have negative impact on quality of life of patients, it rarely incapacitate the patients .
A possible limitation in this study is failure to categorize tooth surface loss according to its severity. Severity of oral diseases has been reported to be closely related with the impact on quality of life of patients. Vargas-Ferreira et al.  reported that low levels of TSL severity did not cause pain or any other psychosocial discomfort for children and this was corroborated by Pires de Andrade et al. .
Attrition is the most common form of TSL in this study and TSL affected individuals belonging to different age groups. The prevalence of impact of TSL on oral health quality of life was high. Pain and inability to chew were the major effects of TSL on oral health related quality of life.
Appendix 1: Questionnaire
This questionnaire is to assess the impact of tooth surface loss on the quality of life of patients seen in a Nigerian Teaching Hospital. Kindly provide honest answers based on your personal experience. The information you provide will be used for the above study without making any reference to you personally. (Are you willing to grant the interview? Yes …………….. No ………….)
1) Age …………
2) Gender ………………
3) Occupation ……………..
4) Level of education ………………..
5) Religion ……………………
6) For how long have you had problem with your tooth/teeth? …………
7) Teeth with tooth surface loss …….
8) Types of tooth surface loss…………
What is your experienced in the last 6 months in regard to the following questions?
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