Tooth loss and oral health-related quality of life: a systematic review and meta-analysis

Abstract

Background: It is increasingly recognized that the impact of disease on quality of life should be taken into account when assessing health status. It is likely that tooth loss, in most cases being a consequence of oral diseases, affects Oral Health-Related Quality of Life (OHRQoL). The aim of the present study is to systematically review the literature and to analyse the relationship between the number and location of missing teeth and oral health-related quality of life (OHRQoL). It was hypothesized that tooth loss is associated with an impairment of OHRQoL. Secondly, it was hypothesized that location and distribution of remaining teeth play an important role in this.

Methods: Relevant databases were searched for papers in English, published from 1990 to July 2009 following a broad search strategy. Relevant papers were selected by two independent readers using predefined exclusion criteria, firstly on the basis of abstracts, secondly by assessing full-text papers. Selected studies were grouped on the basis of OHRQoL instruments used and assessed for feasibility for quantitative synthesis. Comparable outcomes were subjected to meta-analysis; remaining outcomes were subjected to a qualitative synthesis only.

Results: From a total of 924 references, 35 were eligible for synthesis (inter-reader agreement abstracts κ = 0.84 ± 0.03; full-texts: κ = 0.68 ± 0.06). Meta-analysis was feasible for 10 studies reporting on 13 different samples, resulting in 6 separate analyses. All studies showed that tooth loss is associated with unfavourable OHRQoL scores, independent of study location and OHRQoL instrument used. Qualitative synthesis showed that all 9 studies investigating a possible relationship between number of occluding pairs of teeth present and OHRQoL reported significant positive correlations. Five studies presented separate data regarding OHRQoL and location of tooth loss (anterior tooth loss vs. posterior tooth loss). Four of these reported highest impact for anterior tooth loss; one study indicated a similar impact for both locations of tooth loss.

Conclusions: This study provides fairly strong evidence that tooth loss is associated with impairment of OHRQoL and location and distribution of tooth loss affect the severity of the impairment. This association seems to be independent from the OHRQoL instrument used and context of the included samples.

Figure 1

Flow chart outlining the search strategy and results along various steps.

Figure 2

Synthesis of two studies presenting differences in mean OHIP total scores. Forest plots presenting differences in mean OHIP total scores of categories of number of present teeth for three samples (total n = 12,965) [25,43]. The category 25-32 teeth was used as reference. Relative box size indicates the weight of the study: (a) 1-8 teeth (heterogeneity Q = 16.75; df = 2), (b) 9-16 teeth (heterogeneity Q = 17.80; df = 2), (c) 17-20 teeth (heterogeneity Q = 22.06; df = 2), (d) 21-24 teeth (heterogeneity Q = 15.51; df = 2).

Figure 3

Synthesis of two OHIP studies presenting Odds Ratio's. Forest plot presenting Odss Ratio's (OR) for having OHIP impacts (fairly/very often) of two categories of number of present teeth (incomplete vs. complete [26] and ≤ 24 vs. ≥ 25 [25]) in two samples (total n = 6821). Relative box size indicates weight of the study (heterogeneity Χ² = 0,00; df = 1).

Figure 4

Synthesis of three OIDP studies presenting Odds Ratio's. Forest plots presenting Odss Ratio's (OR) for having any impact on OIDP of three categories of number of present teeth in three samples (total n = 2204) [5,24,45]. Relative box size indicates weight of the study. (a) ≤ 10 vs. ≥ 21 (heterogeneity Χ² = 0.08; df = 2), (b) >10 and < 21 vs. ≥ 21 teeth (heterogeneity Χ² = 0.46; df = 2).

Figure 5

Synthesis of two OIDP studies presenting Odds Ratio's in relation to occluding pairs and location. Forest plots presenting Odss Ratio's (OR) for having any impact on OIDP of two categories of number of natural occluding pairs (NOPs) and posterior occluding pairs (POPs) and unrestored anterior spaces (UAS) in two samples (total n = 1184) [5,45]. Relative box size indicates weight of the study. (a) NOPs 0-8 vs. 9-16 (heterogeneity Χ² = 1.17; df = 1), (b) POPs 0-3 vs. 4-8 (heterogeneity Χ² = 0.06; df = 1), (c) UAS yes vs. no (heterogeneity Χ² = 5.03; df = 1).

Figure 6

Synthesis of two studies presenting differences in mean GOHAI total scores. Forest plot presenting differences in mean GOHAI total scores between two categories of number of present teeth: 0-19 teeth vs. 20+ teeth in two samples (total n = 435) [38,46]. Relative box size indicates weight of the study (heterogeneity Q = 2.00; df = 1).

Figure 7

Synthesis of two studies presenting differences in mean OHQoL-UK^© total scores in four samples. Forest plot presenting differences in mean OHQoL-UK^© total scores between two categories of numbers of present teeth: 0-19 teeth vs. 20 and more teeth in four samples (total n = 2738) described in two studies [31,35]. Relative box size indicates weight of the study (heterogeneity Q = 0.15; df = 3).