TMD and occlusion part II. Damned if we don't? Functional occlusal problems: TMD epidemiology in a wider context

Abstract

Objectives To review studies investigating how functional occlusion may relate to TMD and how bruxism may relate to TMD; to review the epidemiology of TMD and relate this to the context of clinical occlusal studies and other aetiological factors. Defi ciencies in study design are highlighted and suggestions made to improve future study designs in order to provide an evidence-base for clinical practice. Design Review article. Methods Electronic databases (MEDLINE and the Cochrane Database of Systematic Reviews) were used to select relevant and frequently cited studies (mean: 40 citations). Citation rate was confi rmed using the Web of Science. Study designs are reviewed and weaknesses and implications discussed. Results Evidence is lacking to suggest functional occlusal factors cause TMD. Investigation of other aetiological factors has been relatively neglected. Conclusions Neither static nor dynamic occlusal factors (including orthodontics) can be said to 'cause' TMD. However, other potential aetiological factors exist which would benefi t from more investigation. This, together with improved study designs, would help provide a stronger evidence-base for clinical practice in the future.

The association between Occlusion Time and Temporomandibular Disorders

“…Because of the different methods used to assess TMD symptoms, which are often subjective, literature reports that the world-wide prevalence of TMD varies between 7% and 84% of the population within an age range of 3-74 years (Luther, 2007). Mostly it seems to afflict 10% of the population over 18 years of age, where chronic pain is experienced in the Temporomandibular region (LeResche, 1997).…”

“…Recent review articles (Luther, 2007;Türp and Schindler, 2012) underline that the evidence supporting a relationship between occlusion and TMD is still not voluminous, such that the authors suggested that the occlusion played a minor role in the development of the signs and symptoms Temporomandibular Disorders, noted that it would be important to establish evidence that a true cause and effect relationship exists between occlusion and TMD (Tecco et al, 2011).…”

TMD and occlusion part I. Damned if we do? Occlusion: the interface of dentistry and orthodontics

“…However, this is not to say that any links with malocclusion are entirely spurious -it may be that more complex interpretation is required, as described below and in Part II. 4 It is also necessary to investigate facial growth, as this will infl uence the type of malocclusion seen.…”

“…(For a critique of this study, see the 14 pages of letters subsequently printed in an issue of the same journal). 22 The problem of distinguishing causality from correlation is returned to in Part II, 4 but the possibility that TMD causes malocclusion rather than malocclusion causing TMD should at least be considered.…”

“…Part I of this paper will examine the possibilities in terms of malocclusion, TM disc position, facial growth and orthodontic treatment. Part II 4 will examine relationships between functional occlusion and bruxism, but will also examine important epidemiological aspects and place TMD in a wider context. • Reviews and investigates evidence relating malocclusion to TMD.…”