Growth relativity hypothesis1

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Growth relativity hypothesis -John voudouris, 2000:

Growth relativity hypothesis -John voudouris, 2000 www.indiandentalacademy.com

PowerPoint Presentation:

www.indiandentalacademy.com INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com

Growth relativity hypothesis:

Growth relativity hypothesis Hypothesis presented for the mechanism of condylar-fossa growth modification with propulsive mandibular appliances, such as the Herbst & Twin-block www.indiandentalacademy.com

Growth relativity hypothesis:

Growth relativity hypothesis Introduction Extensive use of orthopaedic appliances – Herbst, Twin-block & other auxiliaries “Why” & “How” www.indiandentalacademy.com

Growth relativity hypothesis:

Growth relativity hypothesis Normal C-GF growth Condylar remodelling Pathosis at the condyle …. adaptation www.indiandentalacademy.com

Growth relativity hypothesis:

Growth relativity hypothesis Condylar modification Genetic theory– Genetic control pre-natal Effectiveness of orthopaedic appliances on condylar growth ?- Brodie www.indiandentalacademy.com

Growth relativity hypothesis:

Growth relativity hypothesis cybernetic theory – hyperactivity of LPM anatomic research – no significant attachment of LPM to the condyle other muscle & tendon attachments – deep masseter , temporalis - Rees www.indiandentalacademy.com

Growth relativity hypothesis:

Growth relativity hypothesis www.indiandentalacademy.com

Growth relativity hypothesis:

Growth relativity hypothesis www.indiandentalacademy.com

Growth relativity hypothesis:

Growth relativity hypothesis LPM tendon – anterior border of fibrous capsule www.indiandentalacademy.com

Growth relativity hypothesis:

Growth relativity hypothesis Whetten & johnston – LPM traction .. Little effect on condylar growth Permanently implanted longitudinal muscle monitoring techniques – postural & functional LPM activity Studies on humans- - Auf der maur -Pancherz -Anchus pancherz www.indiandentalacademy.com

Growth relativity hypothesis:

Growth relativity hypothesis Functional matrix hypothesis – influence of non-skeletal tissues Exact method of condylar growth stimulation? www.indiandentalacademy.com

Growth relativity hypothesis:

Growth relativity hypothesis Increased vertical dimension & decreased LPM activity Condylar pull “stress” – mandibular growth Condylar compression - C-GF modification – Graber & Joho vertical dimension - postural masticatory muscle activity – EMG records by Storey et al www.indiandentalacademy.com

Growth relativity hypothesis:

Growth relativity hypothesis Evidence of decreased muscle activity – use of propulsive orthopaedic appliances Cause for growth modulation ? www.indiandentalacademy.com

Growth relativity hypothesis:

Growth relativity hypothesis Mandibular growth is a composite of regional forces & functional agents of growth control that interact in response to specific extracondylar activating signals – Endow & Hans Extrinsic signals – basis of “Growth relativity theory” www.indiandentalacademy.com

Growth relativity hypothesis:

Growth relativity hypothesis Growth relativity – growth that is relative to the displaced condyles from actively relocating glenoid fossa Growth – long term retention results short term treatment outcomes www.indiandentalacademy.com

Extension of Wolff’s law:

Extension of Wolff’s law Growth relativity states that – “ with orthopaedically displaced condyle , the bone architecture is influenced by the neuromusculature & the contiguous, non – muscular , viscoelastic tissues anchored to the glenoid fossa & the altered dynamics of the fluids enveloping bone” www.indiandentalacademy.com

Growth relativity hypothesis:

Growth relativity hypothesis 3 main foundations Displacement Viscoelasticity Referred force (transduction) www.indiandentalacademy.com

Growth relativity hypothesis:

Growth relativity hypothesis Viscoelasticity -applied to elastic tissues – muscles In G R it applies to all non – calcified tissues Elasticity of -- retrodiskal tissues --fibrous capsule -- Synovial fluid flow -- LPM perimycium -- TMJ tendons & ligaments -- Other soft tissues -- Body fluids www.indiandentalacademy.com

Growth relativity hypothesis:

Growth relativity hypothesis www.indiandentalacademy.com

PowerPoint Presentation:

www.indiandentalacademy.com

Growth relativity hypothesis:

Growth relativity hypothesis Mandibular advancement(displacement) Stretch of non – muscular viscoelastic tissues New bone formation transduction Synovial fluid dynamics Engorged blood vessels Influx of nutrients www.indiandentalacademy.com

PowerPoint Presentation:

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PowerPoint Presentation:

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Growth restriction-glenoid fossa:

Growth restriction-glenoid fossa GF - posteroinferior growth – Bjork, Popovich & Thompson posteriorly directed viscoelastic tissues – effect condyle and GF Reverse growth– relocation anteroinferiorly Class II correction www.indiandentalacademy.com

Growth restriction-glenoid fossa:

Growth restriction-glenoid fossa www.indiandentalacademy.com

Light bulb analogy of condylar growth & retention:

Light bulb analogy of condylar growth & retention www.indiandentalacademy.com

Discussion:

Discussion Epiphysis Vs condyle Tissue separating forces Ephiphyseal cartilages - little short term adaptation potential No fibrocartilagenous cap No significant tissue separating forces Significant short term adaptation potential Presence of fibrocartilagenous cap www.indiandentalacademy.com

Epiphysis Vs condyle:

Epiphysis Vs condyle www.indiandentalacademy.com

Epiphysis Vs condyle:

Epiphysis Vs condyle Condyle dissimilar to epiphysis …functionally …anatomically …immunologically …chemically & …ontogenetically condyle does not act like an epiphysis during orthopaedic treatment www.indiandentalacademy.com

Retention relapse:

Retention relapse Deactivation of modification due to compression of retrodiskal tissues Hence long term adaptation is not clinically significant www.indiandentalacademy.com

Retention relapse:

Retention relapse www.indiandentalacademy.com

Retention relapse:

Retention relapse www.indiandentalacademy.com

conclusion:

conclusion No measurable long-term benefits for the mandible are derived from the first phase of “functional” appliance therapy in a two phase treatment. www.indiandentalacademy.com

Future studies:

Future studies Synovial fluid dynamics Study conducted on primates – using full occlusal coverage herbst block & twin block appliances – hence oppurtunity to use cephalometric histomorphometric electromyographic methods to investigate observed changes www.indiandentalacademy.com

Clinical implications of viscoelasticity:

Clinical implications of viscoelasticity Dentoalveolar changes AP & vertical changes – differential eruption Transverse changes Buccal segment intrusion & extrusion www.indiandentalacademy.com

Bibliography:

Bibliography Contemporary orthodontics – william R.Proffit ; 3 rd edn Orthodontics – Principles and practice -T.M.Graber ; 3 rd edn The primary role of functional matrices in facial growth – AJO-DO 1969 jun :(20-31) The doctrine of functional matrices- AJO-DO 1969 july; 56:no.1 www.indiandentalacademy.com

Bibliography:

Bibliography 5. Twenty years of functional cranial analysis – AJO-DO 1972 may;61:no.5 6. The role of functional matrix in mandibular growth – AJO-DO 1968 apr;38:no.2 7. The capsular matrix –AJO-DO 1969 nov;56:no.5 8. Genetics , epigenetics and causation- AJO-DO 1981 oct;(366-75) www.indiandentalacademy.com

Bibliography:

Bibliography The functional matrix hypothesis revisited The role of mechanotransduction – AJO-DO 1997 July;112:8-11 The role of an osseous connected cellular network- AJO-DO 1997 Aug;112;221-26 The genomic thesis – AJO –DO 1997 Sep;112:338-42 The epigenetic antithesis and the resolving synthesis – AJO-DO 1997 oct;112:410-7 www.indiandentalacademy.com

Bibliography:

Bibliography Factors affecting the growth of the midface –The functional matrix hypothesis : reflections in a jaundiced eye – Lysle E.Johnston Jr GROWTH RELATIVITY HYPOTHESIS 14. Improved clinical use of Twin-block and Herbst as a result of viscoelastic tissue forces on the condyle and fossa in treatment and long – term retention : Growth relativity AJO-DO 2000 Mar;117:247-66 www.indiandentalacademy.com

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