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The importance of occlusion in oral function and dysfunction

The importance of occlusion in oral function and dysfunction. A. De Laat Copenhagen 2007. Introduction. Aim of dentistry and orthodontics in particular : maintenance and restoration of masticatory function Other goals : speech, esthetics, ….

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The importance of occlusion in oral function and dysfunction

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  1. The importance of occlusion in oral function and dysfunction A. De Laat Copenhagen 2007

  2. Introduction • Aim of dentistry and orthodontics in particular : maintenance and restoration of masticatory function • Other goals : speech, esthetics, …. • ? Preventive action concerning development of dysfunction (and pain)

  3. Outline • Dental occlusion and normal jaw function :- mastication, forces - swallowing (and speech)- mastication and development of occlusion • (Mal)occlusion and Temporomandibular Disorders - etiological role ?- management of TMD- other orofacial pains

  4. Mastication Lundeen, Gibbs, 1972-1985

  5. Influence of food

  6. Influence of tooth morphology

  7. Influence of age

  8. Influence of jaw relationshipP. Proeschel (1988, 2006) • Different chewing patterns :

  9. Soft food – Tough food

  10. Angle Class

  11. Cross bite

  12. Reversed sequencing

  13. Conclusion • Differences between groups with different (mal)occlusions or tooth morphology DO exist…..But are they important …?

  14. Bite forceM. Bakke (2006) • “Objective measure” of one parameter • Relatively simple measurement

  15. Maximum Bite Force • Unilateral molars : 300-600 N • Premolars : 70 % • Front teeth : 40 % • Bilateral molars : 140 % - 200 % (PVDF) • Maximum (Eskimo’s) : 1750 N (Waugh 1937) Hagberg 1987, Bakke et al 1989, Ferrario et al 2004, Tortopidis et al 1998

  16. Maximum bite force • Depends on number of teeth • Gender difference • Importance of motivation and cooperation Rugh and Solberg 1972

  17. Maximum bite force • Influence of pain : arthritis or TMD results in decrease of 40 % (Wenneberg et al 1995, Stohler 1999) • Correlated to PPT (Hansdottir and Bakke 2004)

  18. Maximum bite force • Influence of age (constant from 20-50 y, decreases later, Bakke et al 1990) • Decreases with increasing facial height, gonial angle,… (Ingerval & Helkimo 1978, Throckmorton et al 1980, Proffitt et al 1983, Braun et al 1995) • No influence of tooth decay or loss of periodontal support (Miyaura et al 1999, Morita et al 2003)

  19. Maximum bite force • Dentures.... ..and implant-support helps… (Bakke et al 2002, Van Kampen et al 2002)

  20. Malocclusion and bite force • Negative influence of : • overjet on incisal MBF (Ahlberg et al 2003) • unilateral cross-bite (Sonnesen et al 2001) • open bite (Bakke & Michler 1991)

  21. Conclusions • Occlusal contact area seems most correlated, more than malocclusion • But…does it matter,since- only 10-20 % of variation explained(while e.g. thickness of masseter explains 55 %...)- normal chewing forces are only 15-30 % of MBF….

  22. Masticatory ability and performanceP.H. Buschang • Anatomical (occlusal contact area, malocclusion …); physiological (muscle strength, training, gender,…) and psychological components interplay in mastication, and deficiencies in one part can be compensated for by others • “Masticatory performance” is an objective measure, directly linked to food breakdown, nutrition, digestion

  23. Masticatory performance • Particle size distribution of (test-)food, chewed a standard number of cycles • Methodology : fractional sieving • Typical food (peanuts, carrot, bread,…) Optosil, or specially developed test-foods

  24. Masticatory performance is influenced by : • Number of teeth/occluding units (but subjects with missing teeth do not chew longer…)( Helkimo et al 1978, Yurkstas et al 1965, Henrikson et al 1998) • Patients with dentures increase the number of chewing strokes and wait longer to swallow (? Corrected for age ) • Mixed dentition : increase in early, decrease in late phase

  25. MP and malocclusion • Less potent effect than mutilated dentition • In cross-sectional studie, MP of Class III patients is up to 60 % lower (English et al 2002, Lundberg et al 1974, Zhou and Fu 1995). MP of Class II is 30 to 40 % lower (Henrikson et al 1998) but Median Particle Size (MPS) was not significantly different (Toro et al 2006)

  26. MP and malocclusion • After a predetermined number of chewing cycles (20,30,40) , the Median Particle Size is larger in subjects with ICON (index for complexity, outcome,need) < 43 than > 43 • but no differences in particle distribution or masticatory frequency (Ngom 2007)

  27. MP and digestion • Animal experiments clearly indicate relation between food particle size and digestion (Gyimesi et al 1972) • In man, also incompletely chewed food is digested. In elder persons, MP has been linked to GI-problems : 49 % of patients without posterior teeth have gastritis vs 6 % when no teeth are missing (Mumma 1970)

  28. Mastication and developing occlusion • Over the centuries, malocclusion seems to have increased 10-fold and modern life-style and nutrition have been suggested as cause (Corrucini 1984, Varrela 1990,1992), even more than genetics (Townsend et al 1998) • Nutrition influences elevator muscle development and muscle function influences transverse and vertical facial dimensions (Kiliaridis 2006)

  29. CONCLUSIONS • Malocclusion influences the chewing cycle • Number of occlusal contacts and units influences the maximum bite force • Class II and III patients have a lower masticatory performancebut…. • Probably not of clinical significance in non-compromised patients

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