Importancia de la oclusion en la oclusion y disfuncion

The importance of The importance of occlusion in oral occlusion in oral

function and function and dysfunctiondysfunction

A. De Laat A. De Laat Copenhagen 2007Copenhagen 2007

IntroductionIntroduction Aim of dentistry and Aim of dentistry and orthodontics in particular : orthodontics in particular : maintenance and restoration of maintenance and restoration of masticatory functionmasticatory function

Other goals : speech, esthetics, Other goals : speech, esthetics, ….….

? Preventive action concerning ? Preventive action concerning development of dysfunction (and development of dysfunction (and pain)pain)

OutlineOutline Dental occlusion and normal jaw Dental occlusion and normal jaw function :function :- - masticationmastication, forces , forces - - swallowingswallowing (and (and speech)speech)- mastication and development of - mastication and development of occlusionocclusion

(Mal)occlusion and (Mal)occlusion and Temporomandibular Disorders Temporomandibular Disorders - etiological role ?- etiological role ?- management of TMD- management of TMD- other orofacial pains- other orofacial pains

MasticationMastication

Lundeen, Gibbs, 1972-1985

Influence of foodInfluence of food

Influence of tooth Influence of tooth morphologymorphology

Influence of ageInfluence of age

Influence of jaw Influence of jaw relationshiprelationshipP. Proeschel (1988, 2006)P. Proeschel (1988, 2006)

Different chewing patterns :Different chewing patterns :

Soft food – Tough foodSoft food – Tough food

Angle ClassAngle Class

Cross biteCross bite

Reversed sequencingReversed sequencing

ConclusionConclusion Differences between groups with Differences between groups with different (mal)occlusions or different (mal)occlusions or tooth morphologytooth morphologyDO exist…..DO exist…..

But are they important …?But are they important …?

Bite forceBite forceM. Bakke (2006)M. Bakke (2006)

““Objective measure” of one Objective measure” of one parameterparameter

Relatively simple measurementRelatively simple measurement

Maximum Bite ForceMaximum Bite Force Unilateral molars : 300-600 NUnilateral molars : 300-600 N Premolars : 70 %Premolars : 70 % Front teeth : 40 %Front teeth : 40 % Bilateral molars : 140 % - 200 Bilateral molars : 140 % - 200 % (PVDF)% (PVDF)

Maximum (Eskimo’s) : 1750 N Maximum (Eskimo’s) : 1750 N (Waugh (Waugh 1937)1937)

Hagberg 1987, Bakke et al 1989, Ferrario et al 2004, Tortopidis et al 1998

Maximum bite forceMaximum bite force Depends on number of teethDepends on number of teeth Gender differenceGender difference Importance of motivation and Importance of motivation and cooperation cooperation

Rugh and Solberg 1972

Maximum bite forceMaximum bite force Influence of pain : arthritis Influence of pain : arthritis or TMD results in decrease of or TMD results in decrease of 40 % 40 % (Wenneberg et al 1995, Stohler 1999)(Wenneberg et al 1995, Stohler 1999)

Correlated to PPT Correlated to PPT (Hansdottir and Bakke (Hansdottir and Bakke 2004)2004)

Maximum bite forceMaximum bite force Influence of age (constant from 20-Influence of age (constant from 20-50 y, decreases later, 50 y, decreases later, Bakke et al 1990Bakke et al 1990))

Decreases with increasing facial Decreases with increasing facial height, gonial angle,… (height, gonial angle,… (Ingerval & Helkimo Ingerval & Helkimo 1978, Throckmorton et al 1980, Proffitt et al 1983, 1978, Throckmorton et al 1980, Proffitt et al 1983, Braun et al 1995Braun et al 1995))

No influence of tooth decay or loss No influence of tooth decay or loss of periodontal support (of periodontal support (Miyaura et al Miyaura et al 1999, Morita et al 20031999, Morita et al 2003))

Maximum bite forceMaximum bite force Dentures....Dentures....

..and implant-support helps… (Bakke et al 2002, Van Kampen et al 2002)

Malocclusion and bite Malocclusion and bite forceforce

Negative influence of :Negative influence of :- overjet on incisal MBF overjet on incisal MBF (Ahlberg et (Ahlberg et

al 2003)al 2003)- unilateral cross-bite unilateral cross-bite (Sonnesen et al (Sonnesen et al

2001)2001)- open bite open bite (Bakke & Michler 1991)(Bakke & Michler 1991)

ConclusionsConclusions Occlusal contact area seems most Occlusal contact area seems most correlated, more than malocclusioncorrelated, more than malocclusion

But…does it matter,sinceBut…does it matter,since- only 10-20 % of variation - only 10-20 % of variation explainedexplained(while e.g. thickness of masseter explains 55 (while e.g. thickness of masseter explains 55 %...)%...) - normal chewing forces are only - normal chewing forces are only 15-30 % of MBF….15-30 % of MBF….

Masticatory ability and Masticatory ability and performanceperformance

P.H. BuschangP.H. Buschang Anatomical (occlusal contact area, Anatomical (occlusal contact area, malocclusion …); physiological malocclusion …); physiological (muscle strength, training, gender,…) (muscle strength, training, gender,…) and psychological components and psychological components interplay in mastication, and interplay in mastication, and deficiencies in one part can be deficiencies in one part can be compensated for by otherscompensated for by others

““Masticatory performance” is an Masticatory performance” is an objective measure, directly linked to objective measure, directly linked to food breakdown, nutrition, digestionfood breakdown, nutrition, digestion

Masticatory performanceMasticatory performance Particle size distribution of Particle size distribution of (test-)food, chewed a standard (test-)food, chewed a standard number of cyclesnumber of cycles

Methodology : fractional Methodology : fractional sievingsieving

Typical food (peanuts, carrot, Typical food (peanuts, carrot, bread,…) Optosil, or specially bread,…) Optosil, or specially developed test-foodsdeveloped test-foods

Masticatory performance is Masticatory performance is influenced by :influenced by :

Number of teeth/occluding units Number of teeth/occluding units (but subjects with missing teeth (but subjects with missing teeth do not chew longer…)( do not chew longer…)( Helkimo et al Helkimo et al 1978, Yurkstas et al 1965, Henrikson et al 19981978, Yurkstas et al 1965, Henrikson et al 1998))

Patients with dentures increase Patients with dentures increase the number of chewing strokes and the number of chewing strokes and wait longer to swallow (? wait longer to swallow (? Corrected for age )Corrected for age )

Mixed dentition : increase in Mixed dentition : increase in early, decrease in late phaseearly, decrease in late phase

MP and malocclusionMP and malocclusion Less potent effect than mutilated Less potent effect than mutilated dentitiondentition

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

MP and malocclusionMP and malocclusion After a predetermined number of After a predetermined number of chewing cycles (20,30,40) , the chewing cycles (20,30,40) , the Median Particle Size is larger Median Particle Size is larger in subjects with ICON (index for in subjects with ICON (index for complexity, outcome,need) < 43 complexity, outcome,need) < 43 than > 43than > 43

but no differences in particle but no differences in particle distribution or masticatory distribution or masticatory frequency (frequency (Ngom 2007Ngom 2007) )

MP and digestionMP and digestion Animal experiments clearly indicate Animal experiments clearly indicate relation between food particle size relation between food particle size and digestion (and digestion (Gyimesi et al 1972Gyimesi et al 1972))

In man, also incompletely chewed In man, also incompletely chewed food is digested. In elder persons, food is digested. In elder persons, MP has been linked to GI-problems : MP has been linked to GI-problems : 49 % of patients without posterior 49 % of patients without posterior teeth have gastritis vs teeth have gastritis vs 6 % when no teeth are missing (6 % when no teeth are missing (Mumma Mumma 19701970))

Mastication and developing Mastication and developing occlusionocclusion

Over the centuries, malocclusion Over the centuries, malocclusion seems to have increased 10-fold and seems to have increased 10-fold and modern life-style and nutrition modern life-style and nutrition have been suggested as cause (have been suggested as cause (Corrucini Corrucini 1984, Varrela 1990,19921984, Varrela 1990,1992), even more than ), even more than genetics (genetics (Townsend et al 1998Townsend et al 1998) )

Nutrition influences elevator Nutrition influences elevator muscle development and muscle muscle development and muscle function influences transverse and function influences transverse and vertical facial dimensions (vertical facial dimensions (Kiliaridis Kiliaridis 20062006))

CONCLUSIONSCONCLUSIONS Malocclusion influences the chewing Malocclusion influences the chewing cyclecycle

Number of occlusal contacts and units Number of occlusal contacts and units influences the maximum bite force influences the maximum bite force

Class II and III patients have a Class II and III patients have a lower masticatory performancelower masticatory performancebut….but….

Probably not of Probably not of clinicalclinical significance significance in non-compromised patients in non-compromised patients