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Role of facial muscles in complete denture prosthesis
- 1. Role of Facial Muscles in Complete Denture Prosthesis A REVIEW ARTICLE Journal of indian Dental association Dr. Anindita Majumder1, Prof. (Dr.) Sugata Mukherjee2, Prof. (Dr.) Tapan Kumar Giri3, Dr Ashish Barui1, Dr Dibyatanu Majumder1
- 2. CONTENT • Introduction • Development of facial muscles • Facial muscles Muscles of mastication and its accessory muscles Muscles of facial expression • Role of facial muscles in complete denture prosthesis • Conclusion • References
- 3. Introduction • Musculature is involved directly in several important phases of complete dentures. • They exert a direct influence upon the peripheral extensions, shape and thickness of denture bases, position of teeth both horizontally and vertically and facial appearances. • In addition they are active during mastication, speech and deglutition. • The muscles that are intimately involved with prosthedontics are skeletal muscles.
- 4. • In the majority of skeletal muscles ,the origins and insertions are in bone. • However, many skeletal muscles involved in complete denture construction have a bony origin but insert into an aponeurosis, a raphe, or another muscle. • Following group of muscles are studied in relation to complete dentures: Muscles of mastication and its accessory muscles Muscles of facial expression
- 5. Development of facial muscles
- 7. MUSCLES OF MASTICATION TEMPORALIS MEDIAL PTERYGOID LATERAL PTERYGOID MASSETER
- 9. ACCESSORY MUSCLES OF MASTICATION DIGASTRIC MYLOHYOID GENIOHYOID INFRAHYOID
- 10. DIGASTRIC
- 11. MYLOHYOID
- 12. GENIOHYOID
- 13. INFRAHYOID
- 14. MUSCLES OF FACIAL EXPRESSION • These muscles generally donot insert into the bone. They are subcutaneous in position and produces wrinkles or fold in the skin when they contract. • They are responsible for expression of different emotions of an individual. • Also called mimetic muscles.
- 15. MUSCLES OF FACIAL EXPRESSION
- 16. MUSCLES OF FACIAL EXPRESSION
- 17. Role of facial muscles in complete denture prosthesis • Buccinator, Orbicularis oris, Incisivus superioris and inferioris and Bucco- labial groups are of main concern to the Prosthodontist.
- 18. • Orbicularis oris - This muscles rest on the labial flange and gingival third of anterior teeth. Its tone is determined by the support it receives.
- 19. • Buccinator - In the lower jaw buccinator muscles becomes part of denture bearing area • the action of buccinator does not dislodge the denture directly because the muscle fibres contract in a line parallel to plane of occlusion, but they are at right angle to the fibres of masseter.
- 21. • In complete denture prosthesis, it helps in retention of maxillary denture. • Buccal surface of the maxillary denture which incline inward from the border towards the teeth, is in direct contact with the lateral forces from the contracting buccinator muscle.
- 22. • Modiolus - (LATIN, “A HUB OF AWHEEL”) - It is a fibro muscular mass formed by the convergence of various muscles towards a focus just lateral to the buccal angle
- 23. • It is formed by nine muscles. They are divided into two groups • 1. Cruciate modiolar muscles - Zygomaticus major, Levator anguli oris, Depressor anguli oris, Platysma pars modiolaris. • 2. Transverse muscles - Buccinator, Risorius, Orbicularis oris, Incisivus superior & inferior.
- 24. Prosthetic significance : • Border molding: The functional movements are made during the border moulding procedure by holding the modiolus with thumb and index finger. • It helps in establishing the height of occlusal plane of occlusal rim
- 25. Influence of muscles of facial expression on the borders of maxillary dentures : • Labial flange of the denture - lies in the labial vestibule area extending from buccal frenum in the canine region of one side to the other side. • The main muscle of the lip is orbicularis oris, which forms the outer surface of labial vestibule. Its tone depends on the support it receives from flange and position of the teeth
- 26. Buccal flange of the denture – • It lies in the buccal vestibule extending from the buccal frenum to hamular notch • It is in relation with three muscles • 1. Levator anguli oris – which lies beneath the frenum and affects its position. • 2. Orbicularis oris – which pulls the frenum forward. • 3. Buccinator – pulls it back.
- 27. • Buccal vestibule – • Width of the vestibule is influenced by the action of buccinator. Distobuccal end of flange is affected by the masseter and coronoid process. • Hamular notch - • area is influenced by action of buccinator and suprior constrictor into pterygomandibular raphe. When the mouth is open wide, pterygomandibular raphe becomes taut and pulled forward and overextension of the denture may traumatise the tissue
- 28. • Influence of muscles of facial expression on the borders of mandibular dentures – • Labial frenum : • It contains a band of fibrous connective tissue that helps to attach to orbicularis oris. • Hence this frenum is active and proper relief must be given to permit its movement.
- 29. Orbicularis oris : • also influences the flange thickness. • When the mouth is open wide it becomes stretched narrowing the sulcus and if the flanges are thick it will displace the denture. • Similarly flange thickness would affect the lip support and aesthetics.
- 30. • Mentalis • elevates the skin of the chin and the lip outward. It renders the vestibule shallow
- 31. • Buccal flange of the denture – • Denture should completely cover the buccal shelf despite the fact that it rest on buccinator because fibres of buccinator runs parallel to the base and it contract parallel to the border and not perpendicular to it
- 32. • Distobuccal area of the vestibule is influenced by the action of masseter which press inward against the buccinator, thereby reducing space in that area
- 33. • Distal extension of the denture base is up to the retromolar pad , which is lined by thin non keratinised epithelium and sub-mucosa containing glandular tissues, fibres of the temporalis, attachments of the buccinator and superior constrictor in the pterygomandibular raphe. • When the patient opens the mouth, the pterygomandibular raphe is pull forward and overextension of denture base may cause dislodgement of the denture
- 34. CONCLUSION • Successful denture construction and comfortable wearing of the prosthesis is depended on various factors but amongst all, role of muscles are influential one, and facial muscles are important for coordination between prosthesis performance and facial expression of emotion. Their action must be understood and recorded at all step of fabrication of prosthesis
- 35. REFERENCES • 1. O. Rahn, Charles M. Heartwell. Textbook of Complete Dentures. 5th Edition, BC Decker, 2002. • 2. Debasis Pramanick. Principles of Physiology. 5th Edition. Jaypee. 2015. • 3. A. K. Dutta. Essentials of Human Anatomy – Head and Neck. 6th Edition. Current Books International. • 4. George A. Zarb, Charles L. Bolender, Steven Eckert, Rhonda Jacob, Aaron Fenton, Regina Mericske-Stern. Bouche’s Prosthodontic Treatment for Edentulous Patients. 9th and 12th Edition. Elsevier. • 5. Martone A. L. The Phenomenon of Function Of Complete Denture Prosthodontics. J Prosthet Dent, 1962; 12(6): 1020- 1041. • 6. Beresin VE, Schiesser FJ. The Neutral Zone in Complete Denture. 2006, 95(2): 93-100.