Lecture Introduction to occlusion

Trang 1 INTRODUCTION TO OCCLUSIONPart one Trang 2 Chapter 1: IntroductionMasticatory SystemDefinition of OcclusionChapter 2: Functional Anatomy of Masticatory SystemTemporomandibular Jo

INTRODUCTION TO OCCLUSION Part one ANATOMY AND PHYSIOLOGY OF THE MASTICATORY SYSTEM Chapter 1: Introduction Masticatory System Definition of Occlusion Chapter 2: Functional Anatomy of Masticatory System Temporomandibular Joint Skeletal Components of Masticatory System Masticatory or Jaw Muscles Chapter 3: Considerations of Occlusion Development of Deciduous Dentition Development of Permanent Dentition Considerations of Occlusion Chapter 4: Kinesiology of Occlusion Classification of Positions and Movements of the Mandible Border Movements and Positions of the Mandible Recorded in the Sagittal Plane Border Movements and Positions of the Mandible Recorded in the Horizontal Plane Chapter 5: Functions and Parafunctions Functions: Swallowing (Deglutition), Suckling, Chewing, Speaking Parafunctions: Bruxism, Clenching § INTRODUCTION TO OCCLUSION Goal: After studying this lesson, the student should be able to: present the concept of masticatory system and name the components of the masticatory system define the subject of occlusion; differentiate from teeth articulation or contact between the teeth and occlusion MASTICATORY SYSTEM Individual tooth is of great clinical significance A single tooth, by itself, however, can not perform the necessary masticatory and occlusal functions When the teeth are properly related to each other to form the dental arches and the dentition, they become an essential component of the masticatory system 1.1 Masticatory System and its Components The masticatory system as a whole forms a functional unit, consisting of the teeth and periodontium, the jaws, the temporomandibular joints, muscles involved in moving the mandible (jaw muscles), the lip-cheek-tongue system, the salivary system, the neuromuscular and vascular structures involved in the control, nutrition and maintenance of proper function → Masticatory system is a multicomponent and multifunction system 1.2 GENERAL FUNCTIONS of the human masticatory system The head houses and protects a number of anatomical structures which are necessary for the maintenance of life and well-being of the individual → The masticatory system is but one of several functional units that use anatomical structures in common with other systems The Two Group of Functions of Masticatory System: - Primitive or biological functions: swallowing (deglutition), suckling, chewing - Social functions: Communication functions: including speaking, aesthetic , and Emotional expression The functions of "tools" and "weapons" are still expressed, but not play a decisive role and no longer play the role of a meaningful function of life 2 DEFINITION OF OCCLUSION “Occlusion” is one of the most commonly word used by the dental profession The term “occlusion” is defined in the dictionary as “the act of closure or state of being closed” The Subject of Occlusion: ‒ is NOT limited to the occlusal contact relationship of the teeth ‒ implies much more than the static occlusal contact relationships of the teeth ‒ should includes reference to a dynamic biomechanical musculoskeletal system ‒ encompasses neuromuscular and psychophysiologic areas that may reflect disturbances that occur as a result of, or are the cause of occlusal dysfunction ‒ should have in its definition the concept of a multifactorial functional relationship between the teeth and other components of the masticatory system as well as with other areas of the head and neck that directly or indirectly related to function, parafunction, or dysfunction of the masticatory system Occlusion is defined in many statements: “The relationship between all the components of the masticatory system in normal function, dysfunction and parafunction, including the morphological and functional features of contacting surfaces of opposing teeth and restorations occlusal trauma and dysfunction, neuromuscular physiology, the temporomandibular joint and muscle function, swallowing and mastication, psychophysiological status, and the diagnosis, prevention, and treatment of functional disorders of the masticatory system” (Jablonski, 1982) “Occlusion is the dynamic biological relationship of all components of the masticatory system to the contacting surfaces of the teeth in function and dysfunction, i.e the integrated function of jaw muscles, temporomandibular joints and teeth” (Klineberg, 1991) Occlusion is a subject of the relationship of all components of the masticatory system that related to the contacting occlusal surfaces of the teeth in function, parafunction and dysfunction These relationships are presented mainly on three main components: teeth and periodontal tissues, temporomandibular joints and jaw muscles, which are accumulated over time under certain psychophysiological status conditions Tooth-Tooth contact Tooth-Tooth contact Tooth-Tooth contact DEFINITION OF OCCLUSION Occlusion is the subject of the relationship of all components of the masticatory system that related to the contacting occlusal surfaces of the teeth in function, parafunction and dysfunction These relationships are presented mainly on three main components: teeth and periodontal tissues, temporomandibular joints and jaw muscles, which are accumulated over time under certain psychophysiological status conditions Note: Articulation: in dentistry, the static and dynamic contact relationship between the occlusal surfaces of the teeth during function Teeth & Periodontium T -T Jaw Muscles TMJs Time T – T = tooth–to-tooth contact The Central Role of Occlusion in Dental Education and Practice Occlusion is a complex subject and one of the basic building stones of dentistry It is special importance to the provision of comprehensive patient care in clinical practice In dentistry, the subject of Occlusion is in the unique position to provide a common pool of information that can be used by all of the clinical disciplines The subject of Occlusion is the medium that brings all branches of dentistry together “Occlusion is the red thread which go through all specialty of dental practice” TEETH & SKULLS IN HUMAN EVOLUTION Đồ đá cũ - Sơ kỳ Earliest fire use pleistocene (Lower Paleolithic) “Out of Africa” Protohistory (Sơ Sử) Prehistory (Tiền Sử) pliocene History Lịch sử Trung kỳ (Middle ~) chimpanzee Homo habilis (-2.5 - -1.5 My) Au anamensis (-4.12 My) Ardipithecus ramidus (-6# -4.4 My) Au afarensis “Lucy”(3.4 My) Paranthropus robustus Homo s sapiens (100,000 Y) H s neanderthalensis (-230,000 Y) Au Africanus Interglacial periods (Quaternary glaciation: -2,588,000y to present) holocene H erectus Thẩm Khuyên Homo erectus (-1.8 M – 400,000 Y ) Archaic Homo sapiens (- 300,000 Y) EVOLUTIONAL CHARACTERISTICS OF THE HUMAN MASTICATORY SYSTEM The main dento-facial changes in comparing between modern man and Homo habilis, Homo erectus and Neanderthal man include: A reduction in size of teeth and a reduction in number of cusps in the permanent molars, but little change in tooth form, A greater reduction in size of alveolar processes with a loss of facial prognathism and increasing tendency for crowding of teeth The development of the characteristic chin of modern man Homo erectus H sapiens neanderthalensis H sapiens sapiens EVOLUTIONAL CHARACTERISTICS OF THE HUMAN MASTICATORY SYSTEM (cont’d) The relative proportion of cranium to jaws has changed in human due to both an increase in cranium size and decrease in jaw size These evidences of evolution and comparative anatomy of the masticatory system can explain the potential of abnormal function in human The TMJ is a special structure of the masticatory system in terms of anatomy and evolution: the “temporal” is a part of the cranium that increase in size the “mandible" is a part of the masticatory system, → TMJ is affected by two trends of evolution at the same time Homo erectus H Sapiens neanderthalensis H Sapiens sapiens