Physiologic Basis & Physiologic Basis & Neural Mechanism Of Neural Mechanism Of Functional Functional Appliances Appliances INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.c www.indiandentalacademy.c om om
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Physiologic Basis & Physiologic Basis & Neural Mechanism Of Neural Mechanism Of Functional AppliancesFunctional Appliances
INDIAN DENTAL ACADEMY
Leader in continuing dental education www.indiandentalacademy.com
Aims of Functional Aims of Functional Appliance TherapyAppliance Therapy
•Functional Appliance Therapy aims to Functional Appliance Therapy aims to improve the functional relationship of improve the functional relationship of dentofacial structure by eliminating the dentofacial structure by eliminating the unfavorable factors and improving muscle unfavorable factors and improving muscle environment enveloping the developing environment enveloping the developing occlusion.occlusion.
•Through alteration of teeth and supporting Through alteration of teeth and supporting tissues,a new functional behavior pattern or tissues,a new functional behavior pattern or engram is established that can support a engram is established that can support a new position of equilibrium.new position of equilibrium.
• An Increasing recognition of the interrelationship An Increasing recognition of the interrelationship of form and functionof form and function
• The realization of the neuromuscular involvement The realization of the neuromuscular involvement • Recognition of the importance of airwayRecognition of the importance of airway• Recognition of the role of excessive Recognition of the role of excessive
epipharyngeal lymphoid tissue on head posture epipharyngeal lymphoid tissue on head posture and accomplishment of dentofacial patternand accomplishment of dentofacial pattern
The physiologic basis of The physiologic basis of functional Appliancesfunctional Appliances• Role of RespirationRole of Respiration• Role of tongueRole of tongue• Role of DeglutitionRole of Deglutition• Role of LipsRole of Lips• Role of Temporomandibular JointsRole of Temporomandibular Joints
Role of RespirationRole of Respiration• The size and shape of the nasopharyngeal space must be adequate for The size and shape of the nasopharyngeal space must be adequate for
functional demands functional demands – Linder - Aronson Study I 1960Linder - Aronson Study I 1960
• Mouth breathing was associated with crowding and narrow upper Jaws on patients with Mouth breathing was associated with crowding and narrow upper Jaws on patients with long and narrow faces.long and narrow faces.
– Study II 1970Study II 1970• Adenoidectomies were performed in 81 children with nasal obstruction problemsAdenoidectomies were performed in 81 children with nasal obstruction problems• A comparison of mouth breathers was made with a equal number of nose breathers of A comparison of mouth breathers was made with a equal number of nose breathers of
similar gender and agesimilar gender and age• Children with obstructed nasal breathing were characterized by increase in lower and Children with obstructed nasal breathing were characterized by increase in lower and
total facial heightstotal facial heights• The greatest difference between the two groups was in the vertical development of face The greatest difference between the two groups was in the vertical development of face
and not in the anteroposterior jaw relationand not in the anteroposterior jaw relation• The breathing changed from mouth breathing to nose breathingThe breathing changed from mouth breathing to nose breathing• The breathing pattern remained unchanged The breathing pattern remained unchanged
Role of TongueRole of Tongue• Abnormal Tongue posture and FunctionAbnormal Tongue posture and Function• Primary factor as a consequence of Primary factor as a consequence of
• Secondary FactorSecondary Factor• Adaptive to the unfavorable morphologic pattern Adaptive to the unfavorable morphologic pattern
Functional Appliances are indicated when the role of Functional Appliances are indicated when the role of the tongue malfunction is primarythe tongue malfunction is primary
Role Of LipsRole Of Lips• The configuration of the lips should be studied in relaxed The configuration of the lips should be studied in relaxed
position for assessing incompetencyposition for assessing incompetency• If there is slight contact or a small gap between the upper If there is slight contact or a small gap between the upper
and lower lips,they are said to be competentand lower lips,they are said to be competent• If there is a wide gap , or if the lips are too short ,they can If there is a wide gap , or if the lips are too short ,they can
be considered incompetent. Improvement with orthodontic be considered incompetent. Improvement with orthodontic treatment and exercise is possible only in early stagestreatment and exercise is possible only in early stages
• If the lips seems normally developed but the incisors are If the lips seems normally developed but the incisors are labially tipped making closure difficult, Ballard And Tulley labially tipped making closure difficult, Ballard And Tulley call this as potential lip incompetencecall this as potential lip incompetence
Method Of Operation of Method Of Operation of Functional AppliancesFunctional Appliances
• Theories of Cranio Facial GrowthTheories of Cranio Facial Growth• Genetic Control TheoryGenetic Control Theory
– Genotype supplies all information for phenotypeGenotype supplies all information for phenotype• Cartilage – Directed growth TheoryCartilage – Directed growth Theory
– Scott ( Nasal septum ,condyle ,Synchonedroses )Scott ( Nasal septum ,condyle ,Synchonedroses )• Functional Matrix TheoryFunctional Matrix Theory
Causal Interpretation of mode Of Causal Interpretation of mode Of Operation of Functional AppliancesOperation of Functional Appliances• Functional AppliancesFunctional Appliances
• Increased Contractile activity of LPMIncreased Contractile activity of LPM
• Intensification of repetitive activity of retrodiscal padIntensification of repetitive activity of retrodiscal pad
• Increase in growth stimulating factorsIncrease in growth stimulating factors
• Enhancement of local mediatorsEnhancement of local mediators• STH GROWTH HORMONESTH GROWTH HORMONE• TESTOSTERONETESTOSTERONE• INSULININSULIN• THYROXINTHYROXIN• CALCITONINCALCITONIN• PARATHORMONEPARATHORMONE• GROWTH PROMOTING PEPTIDESGROWTH PROMOTING PEPTIDES
• Reduction of local regulatorsReduction of local regulators
( Factors having negative feed back effects on cell multiplication )( Factors having negative feed back effects on cell multiplication )CYCLIC AMPCYCLIC AMPPROSTAGLANDIN E2PROSTAGLANDIN E2SOMATOSTATIN LIKE SUBSTANCESOMATOSTATIN LIKE SUBSTANCE
• Change in condylar trabecular orientationChange in condylar trabecular orientation
• Additional growth of condylar cartilageAdditional growth of condylar cartilage
• Additional subperiosteal ossification of the posterior border of the mandibleAdditional subperiosteal ossification of the posterior border of the mandible
• Supplementary lengthening of the mandibleSupplementary lengthening of the mandible
Neural Pathway for reflex and Neural Pathway for reflex and Volitional control of the Masticator Volitional control of the Masticator NucleusNucleus• Proprioceptive fibers arising from Periodontal membrane ,Muscles of Proprioceptive fibers arising from Periodontal membrane ,Muscles of
Mastication,TMJMastication,TMJ
• Ascend Via Trigeminal nerve to the brain stemAscend Via Trigeminal nerve to the brain stem
• Mesencephalic nucleusMesencephalic nucleus
• Descends to the masticator nucleus on the ipsilateral sideDescends to the masticator nucleus on the ipsilateral side
• Synapses with the lower motor neuronSynapses with the lower motor neuron
• Caries motor impulses to the muscles of mastication via Trigeminal NerveCaries motor impulses to the muscles of mastication via Trigeminal Nerve
Mechanism of Skeletal Mechanism of Skeletal Muscle ContractionMuscle Contraction
• Functional SignificanceFunctional Significance– Serves as a mechanism for Serves as a mechanism for
upright postureupright posture
– Acts in the mandibular Acts in the mandibular musculature to maintain musculature to maintain Postural rest position of Postural rest position of the mandible in relation to the mandible in relation to maxillamaxilla
Role of Lateral Pterygoid Muscle in Role of Lateral Pterygoid Muscle in Growth Of Condylar CartilageGrowth Of Condylar Cartilage
• Multiplication of Skeletoblasts in condylar cartilageMultiplication of Skeletoblasts in condylar cartilage
• Skeletoblasts differentiate in to prechondroblastsSkeletoblasts differentiate in to prechondroblasts
• Resection of LPMResection of LPM
• Significant slowing of condylar cartilage growth rateSignificant slowing of condylar cartilage growth rate
• Skeletobalsts no longer differentiate in to prechondroblastsSkeletobalsts no longer differentiate in to prechondroblasts
• Percentage of skeletoblasts increases to the detriment of the prechodrobalstsPercentage of skeletoblasts increases to the detriment of the prechodrobalsts
• Prechondroblasts decreases in numberPrechondroblasts decreases in number
• Skeletoblasts begin differentiating in to Preosteoblasts and OsteoblastsSkeletoblasts begin differentiating in to Preosteoblasts and Osteoblasts
• The condyle then increases in size through periosteal type of growthThe condyle then increases in size through periosteal type of growth
• Prechondroblasts may have an inhibiting effect on the skeletoblasts differentiating in to preosteoblastsPrechondroblasts may have an inhibiting effect on the skeletoblasts differentiating in to preosteoblasts
• The retrodiscal pad controls the mandibular growth in two ways The retrodiscal pad controls the mandibular growth in two ways – Vascular ComponentVascular Component
• Controls the condylar cartilage growth rate and endochondral ossification Controls the condylar cartilage growth rate and endochondral ossification raterate
• An increase in activity of the retrodiscal pad produces an increase in An increase in activity of the retrodiscal pad produces an increase in condylar cartilage growth ossificationcondylar cartilage growth ossification
– Biomechanic ComponentBiomechanic Component• Governs both bone apposition and condylar growth direction at posterior Governs both bone apposition and condylar growth direction at posterior
border of the ramusborder of the ramus• An increase in the interactivity of the retrodiscal pad produces an An increase in the interactivity of the retrodiscal pad produces an
accentuation of the ramus posterior concavity and a local increase in bone accentuation of the ramus posterior concavity and a local increase in bone apposition and he number of negative charges at the ramus posterior apposition and he number of negative charges at the ramus posterior concavity surfaceconcavity surface
• It also produces an accentuation of the ramus anterior convexity and a local It also produces an accentuation of the ramus anterior convexity and a local increase in bone resorption and the number of positive charges at the increase in bone resorption and the number of positive charges at the ramus posterior convex surfaceramus posterior convex surface
• Interruption of the circulatory dependence on the blood supply Interruption of the circulatory dependence on the blood supply originating directly from LPM and directly through the retrodiscal pad originating directly from LPM and directly through the retrodiscal pad may contribute to the inhibited differentiation of skeletoblastsmay contribute to the inhibited differentiation of skeletoblasts
• Surgical excision of the retrodiscal pad and anteriorly displaced Surgical excision of the retrodiscal pad and anteriorly displaced articular disks,destroying intracapsular metabolism pump function of articular disks,destroying intracapsular metabolism pump function of the retrodiscal pad, dramatically demonstrates the mechanistic the retrodiscal pad, dramatically demonstrates the mechanistic Iatrogenic potential of nonphysiologic surgeryIatrogenic potential of nonphysiologic surgery
• After surgical resection of the LPM the growth of the condylar cartilage After surgical resection of the LPM the growth of the condylar cartilage and the lengthening of the mandible continue but are significantly and the lengthening of the mandible continue but are significantly reduced.reduced.
Condylar Cartilage - Growth DirectionCondylar Cartilage - Growth Direction
• Mitosis distribution Mitosis distribution and area of and area of concentration a concentration a sagittal section of sagittal section of condylar cartilage.The condylar cartilage.The cartilage surface is cartilage surface is divided in to 4 divided in to 4 sectionssections www.indiandentalacademy.comwww.indiandentalacademy.com
Endochondral Bone Trabeculae in Endochondral Bone Trabeculae in Mandibular CondyleMandibular Condyle
Intrinsic Regulation of Intrinsic Regulation of condylar Cartilage Growth condylar Cartilage Growth RateRate• The acceleration Maturation The acceleration Maturation
of Chondroblastsof Chondroblasts– Growth Stimulating effect of Growth Stimulating effect of
ThyroxinelThyroxinel
• Chondroblasts Hypertrophy Chondroblasts Hypertrophy Prechondroblasts Division Prechondroblasts Division Restraining Signal Restraining Signal – Growth Stimulating effect of Growth Stimulating effect of