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Occlusion 26 /certified fixed orthodontic courses by Indian dental academy
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The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.

Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
0091-9248678078

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Occlusion 26 /certified fixed orthodontic courses by Indian dental academy Occlusion 26 /certified fixed orthodontic courses by Indian dental academy Presentation Transcript

  • INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  • CONTENTS 1) 2) 3) 4) 5) Introduction Definition Review of Literature Concepts of Occlusion Development of Occlusion (a) Mouth of Neonate Gum Pad Stage Precociously erupted primary teeth (b) Deciduous Dentition Eruption age and sequence of deciduous dentition Characteristics of Primary Dentition Spacing Normal Overbite & Deep Bite Inter Incisal Angle Occlusal Relations (c) Mixed Dentition Period First Transitional Period Inter Trasitional Period Second Transitional Period. (d) Self Correcting Dental Anomalies www.indiandentalacademy.com
  • 6) Permanent Dentition (a) Alignment and Occlusion of Dentition Dental Arch Form (b) Intra Arch Alginment Curvatures of Occlusal Plane (c) Inter Arch Alignment Arch Length Arch Width Bucco-occlusal contact relationship Mesio Occlusal Contact Relationship (in posteriors) Class-I Class-II Class-III Common Occlusal Relationship of Anterior Teeth (d) Andrew’s Six Keys to Occlusion (e) Various Mandibular Movements & Occlusal Contacts during these movements. 7) Types of Occlusion 8) Bio-Mechanics of Occlusion 9) Applied Aspects 10) Occlusion in Prosthodontics 11) Conclusions 12) References. www.indiandentalacademy.com
  • INTRODUCTION  Occlusion --> Ob + Claudre " To Close Up"  The term "occlusion' used in dentistry means contact relationship of teeth in function or parafunction.  However, term refers not only to contact of arches at an occlusal interface but also to all those factors concerned with development and stability of masticatory system and with use of teeth in oral motor behaviour. The primary components of human dental occlusion are : (a) The dentition (b) Neuro Muscular System (c) Cranio facial structures.  The development and maturation of these components are inter-related, so that growth, adaptations and change actively participate in development of adult occlusion. www.indiandentalacademy.com
  • DEFINITION  According to GPT/8 : Occlusion may be defined as : - act or process of closure or being closed or shut off. - static relationship between incisal and masticatory surfaces of maxillary or mandibular teeth / tooth analogues.  In latin Occ = Up Clusion Closing  JABLONSKI (1982) It is relationship between all components of masticatory system in normal function, parafunction and dysfunction including morphology, and functional features of contacting surfaces of opposing teeth and restorations, occlusal trauma, neuromuscular physiology, psychophysiological state and the diagnosis, prevention and treatment of functional disorders.  DYNAMIC OCCLUSION (Davies and Gray) Refers to the occlusal contacts that are made whilst mandible is moving relative to the maxilla, the mandible being guided by muscles of mastication and anterior and posterior guidance mechanism of mandible, Anterior guidance of teeth which may touch during eccentric movement of mandible, posterior guidance, TMJ. www.indiandentalacademy.com
  •  As defined by Dorland's Medical Dictionary          Occlusion is Act of closure or state of being closed. According to "WHEELERS occlusion refers not only to contact of arches at an occlusal interface but also to all those factors concerned with development and stability of masticatory system and with use of teeth in oral motor behaviour. According to Bishara, Occlusion is way maxillary and mandibular teeth articulates. Ash and Ramfjord defines occlusion as contact relationship of teeth in function and parafunction. In reality, Dental Occlusion is much more complex relationship because it involves study of : Teeth : Morphology : angulation Muscles of Mastication Skeletal Structures TMJ Functional Jaw Movements. www.indiandentalacademy.com
  • Review of Literature  Peter E. Dawson in an article quoted a classification system for a occlusions that relate maximal intercuspation to the position and condition of temporomandibular joints.  A recently introduced term ‘adaptive centric posture’ is used in this classification to distinguish deform TMJs that have remodeled or adapted to a conformation that can comfortably accept maximal loading. www.indiandentalacademy.com
  •  Classification of Occlusion:  Type I Maximal intercuspation occurs in harmony with the verifiable centric relation  Type I (A) Maximal intercuspation occurs in harmony with adaptive centric posture.  Type II Condyles must displace from verified centric relation for maximal intercuspation to occur.  Type II (A) Condyles must displace from adaptive centric posture for maximal intercuspation to occur  Type III Centric relation or adaptive centric posture can not be verified. The TMJs accepts loading without causing discomfort, so the relationship of maximal intercuspation to correct condyle position can not be immediately determined.The condition is diagnosed as transitory and treatable to achieve centric relation or adaptive centric posture  Type IV occlusal relationship is in a stage of progressive disorder because of pathologically unstable and actively progressive deformity of TMJs. Type IV occlusion may be described specifically as (1) progressive open . occlusion (2) Progressive asymmetry (3) progressive mandibular retrusion www.indiandentalacademy.com
  • CONCEPTS OF OCCLUSION           GNATHOLOGICAL APPROACH PHILOSOPHY OF ARNE G. LAURITZEN NILES GUICHET AND GNATHOLOGY VISION OF TRANSOGRAPHIC CONCEPT FREEDOM IN CENTRIC CONCEPT OCCLUSAL CONCEPTS OF SCHUYLER BEYRON’S OCCLUSAL CONCEPTS THE PANKEY – MANN PHILOSOPHY DAWSON’S CONCEPT OF COMPLETE DENTISTRY GERBER’S CONDYLAR DISPLACEMENT THEORY www.indiandentalacademy.com
  •  DEVELOPMENT OF OCCLUSION MOUTH OF NEONATE (1) Gum Pads : Alveolar processes at birth are called Gum Pads There are horse shoe shaped Consist of 2 parts : labiobuccal and lingual. The 2 portions of gum pads are separated from arch other by groove called Dental Groove. The gum pads are divided into 10 segments by certain grooves called Transverse Grooves. Each of these segments consist of one developing deciduous tooth sac. Gingival Groove Separates gum pad from palate and floor of mouth. Transverse groove between canine of first deciduous molar segment is called lateral sulcus. The lateral sulcii are useful in judging interarch relationship in early stage. The lateral sulcus of mandibular arch is normally more distal to that of maxillary arch. www.indiandentalacademy.com
  •  Upper and lower gum pads are almost similar to each other. Upper gum pad is both wide as well as longer than mandibular gum pad. Thus when upper and lower pads are approximated there is complete overjet all around. Contact occurs between upper and lower gum pads in first molar region and space exists between them in anterior region. This infantile open bite is considered normal & helps in suckling www.indiandentalacademy.com
  • DECIDUOUS DENTITION Any considerations of development of occlusion should begin with occlusion of Deciduous teeth. (a) Eruption Age and Sequence of Deciduous Dentition : Mandibular central Incisors are 1st teeth to erupt by 6-7 months of age Variation of 3 months from mean age has been accepted as normal Sequence of eruption is : A - B - D - C - E. (b) Characteristics of Primary Dentition (1) Spacing (i) Physiologic Spacing Normal spaces between deciduous teeth Help to accommodate larger permanent successors Baume in 1950 termed it as : Closed arch dentition Spaced arch dentition www.indiandentalacademy.com
  • (ii) Primate Space (Anthropoid / Simian Space) The spacing found mesial to maxillary cuspids and distal to mandibular cuspids are termed as Primate spaces. (iii)Delabarre in 1918 was the first to describe inter proximal spacing in primary dentition. (2) Normal Overbite and Deepbite Normal overbite is usually present in children. In some cases, deep bite is present during initial stages of development. Later deepbite is reduced due to : - Eruption of deciduous molars. - Attrition of Incisors - Forward movement of mandible due to growth. www.indiandentalacademy.com
  • (3) Overbite and Overjet During Primary dentition - Overbite decreases by slight amount. - Overjet reduced to zero. From the early mixed dentition to completion of permanent occlusion. average overbite increases slightly and then decreases. (4) Inter Incisal Angle : It is angle formed between the intersection of long axis of upper incisors and lower incisors. In Primary dentition, as incisor are more upright, there is an increase in Inter incisal angle. (5) Occlusal Relations Baumes Classification (a) Flush terminal plane - 76% (b) Mesial Step Terminal Plane - 14% (c) Distal Step Terminal Plane - 10% www.indiandentalacademy.com
  • Flush terminal Distal step Mesial step www.indiandentalacademy.com
  • Mixed Dentition Period - Begins at approximately 6 years of age. - Classified into 3 phases : (a) First Transitional Period : Characterized by : (i) Emergence of 1st permanent molars. • Mandibular 1st molar - 1st permanent tooth to erupt at 6 years of age. • Location and relationship depends upon distal surface relationship upper and lower 2nd deciduous molars. www.indiandentalacademy.com
  • BAUMES CLASSIFICATION Flush Terminal Plane : • 76 %Distal surface of upper and lower 2nd deciduous molars are in one vertical plane. Thus erupting 1st permanent molars may be in a flush or end on relationship. This is normal feature of deciduous dentition. For transition of such an end on molar relation to class - I molar relation, the lower molar has to move forward by about 3-5mm relative to upper molar. This occurs by utilization of Physiologic spaces and leaving space in lower arch and by differential forward growth of mandible. • Shift of lower molar from flush terminal plane to class - I relation can occur in 2 ways : (i) Early (ii) Late Shift  Early shift occurs during early mixed dentition period. Eruptive force of 1st permanent molar is sufficient to push deciduous first and 2nd molars forward in arch to close primate space and thereby establish class I molar relationship.  Many children lack primate space and thus erupting permanent molars are unable to move forward to establish Class I relationship. In these cases, to when deciduous 2nd molar exfoliate the permanent first molar drift mesially utilization leeway space. This occur in late mixed dentition period and is thus called late shift. www.indiandentalacademy.com
  • Mesial Step Terminal Plane (14%) : In this type of relationship distal surface of lower 2nd deciduous molar is more mesial than that of upper. This permanent molars erupt directly in Angles Class - I occlusion. This type of mesial step terminal plane most commonly occur due to early forward growth of mandible. If differential growth of mandible in forward direction persists, it can lead to Angles Class-III malocclusion Distal Step Terminal Plane (10%) This is characterized by distal surface of lower 2nd deciduous surface of lower 2nd deciduous molar being more distal to that of upper. Thus erupting molars may be in Angle's class II malocclusion. www.indiandentalacademy.com
  • (ii) Exchange of Incisors - Permanent Incisors are larger in size than primary. - Warren Mayne gave Incisal liability in 1969. This is difference between amount of space needed for accommodation of incisors and amount of space available for this : - In maxilla - 7mm. In mandible - 5mm. - Incisor liability is overcome by following factors.  Utilization of Inter dental spaces seen in primary dentition.  Increase in Inter canine width.  Change in Incisor Inclination.  Incisor Position. www.indiandentalacademy.com
  • b) Inter Transitional Period This phase during mixed dentition period is relatively static and no change occurs. (c)Second Transitional Period - Characterized by replacement of deciduous molars and canines by permanent premolars and canine respectively - Leeway Space of Nance - The combined mesiodistal width of permanent canines and premolars is usually less that that of deciduous canines and molars. In Maxilla 1.8mm In Mandible 3.4mm. This excess space available after exchange of deciduous molars and canines is utilized for mesial drifts of mandibular molars to establish class I molar relation. www.indiandentalacademy.com
  • SELF CORRECTING DENTAL ANOMALIES These anomalies occur in certain period of development and get corrected by themselves as development progresses. These are also called Transient or self correcting malocclusion I. During Gum Pad Stage - Increased overjet all around - Reterognathic relation of lower gum pad. - Anterior open bite. - Infantile swallow. II. During Deciduous - Spacing Physiologic spaces Primate spaces - Anterior deep bite - Molar Relationship. III. During Mixed Dentition - End on molar relationship. - Incisal Liability www.indiandentalacademy.com
  • Ugly - Duckling Stage - Also known as "Broad Bent Phenomenon". Seen at around 10 - 13 years of age. In this there is unesthetic metamorphosis leading to Esthetic Results. This is particular situation seen during eruption of permanent canines. As developing permanent canines erupt, they displace roots of lateral incisor mesially. This result in transmitting of force on to roots of central incisors which gets displaced mesially. A resultant divergence of crowns of 2 central incisors cause midline spacing. The condition usually corrects by itself when canines erupt and pressure is transferred from roots to coronal area of incisors. www.indiandentalacademy.com
  • PERMANENT DENTITION  Permanent dentition forms within jaws soon after birth, except for cusps of 1st permanent molars which form before birth. Permanent incisors develop lingual or palatal to deciduous incisors and move labially as they erupt. Premolars develop below diverging roots of deciduous molars. Eruption sequence of permanent dentition may exhibit variation. Frequently seen sequence in maxillary arch are : 6 - 1 - 2 - 4 - 3 - 5 - 7. or 6 - 1 - 2 - 3 - 4 - 5 - 7. In mandibular arch 6 - 1 -2 - 3 - 4 - 5 - 7 or 6 – 1- 2 - 4 - 3 - 5 - 7. www.indiandentalacademy.com
  • Alignment and Occlusion of Dentition : Dental Arch Form • The teeth are positioned on maxilla and mandible in such a way as to produce curved arch when seen from occlusal surface. The arch form is in large part determined by shape of underlying basal bone. • On basis of qualitative observations, antheropologists have described general shape of palatal arch as being paraploid, Ushaped, ellipsoid, round and horse shoe shape • Discrepancies in arch between the maxillary and mandibular arches generally result in poor occlusal relationships. INTRA ARCH ALIGNMENT Intra arch tooth alignment refers to relationship of teeth to each other within dental arch. The occlusal planes of dental arches are curved in manner that permits maximum use of tooth contact during function as flat occlusal plane will not permit simultaneous functional contact in more than one area of dental arch. www.indiandentalacademy.com
  •  The occlusal surfaces of teeth are made up of numerous cusps, grooves and sulci. During function these occlusal elements permit effective breaking up of food and mixing with saliva to form bolus that is easily swallowed.  The area of tooth between, buccal and lingual cusp tips of posterior teeth is called occlusal table . The major forces of mastication are applied on this area. The occlusal table represents approximately 50% - 60% of total buccolingual dimension of posterior tooth and is postitioned over long axis of root structure. It is called inner aspect of tooth because it falls between cusps tips. Likewise, occlusal area outside cusp tips is called outer aspect. The inner and outer aspects of tooth are made up of inclines that extend from cusp tips to either the central fossa.  Contour on lingual and labial surfaces of teeth. Thus these inclines are called inner and outer inclines. www.indiandentalacademy.com
  •  CURVATURES OF OCCLUSAL PLANE Curve of Spee When examining the arches from lateral view, mesiodistal axial relationship can be seen. If lines are extended through long axis of roots occlusally through crowns, angulation of teeth with respect of alveolar bone can be observed. In mandibular arch both anterior and posterior teeth are mesially inclined. The second and third molars are more inclined premolars. In maxillary arch a different pattern of inclination erupts. The anterior teeth are generally mesially inclined, with most posterior molars being distally inclined. If from lateral view an imaginary line is draw through buccal cusp tips of posterior teeth. Curved line following plane of occlusion will be established that is convex in maxillary arch and concave in mandibular arch. The convex and concave lines match perfectly when dental arches are placed into occlusion. This curvature of dental arches was first described by Von Spee & is therefore referred to as Curve of Spee www.indiandentalacademy.com
  • Curve of Wilson : When observing dental arches from frontal view, buccolingual axial relationship can be seen. Generally posterior teeth in maxillary arch have slight buccal inclination. In mandibular arch posterior teeth have slightly lingual inclination. If a line is drawn through buccal and lingual cusp tips of both right and left posterior teeth, curved plane of occlusion will be observed. The curvature is convex in maxillary arch and concave in mandibular arch. Again, if arches are brought into occlusion, tooth curvatures will match perfectly. This curvature in occlusal plane observed from frontal view is called CURVE OF WILSON www.indiandentalacademy.com
  • Curve of Monsoon Bonwill, one of first to describe dental arches, noted that an equilateral triangle existed between centres of condyles and mesial contact areas of mandibular central incisors. He depicted this as having 4-inch sides. In other words, the distance from mesial contact area of mandibular central incisor to centre of either condyle was 4 inches and distance between centres of condyles was 4 inch. In 1932, Monson, used Bonwill's triangle and proposed a theory that sphere erusted with radius of 4 inches, with centre that was an equal distance from occlusal surfaces of posterior teeth and from centres of condyles. The curve formed was known as CURVE OF MONSON www.indiandentalacademy.com
  • INTER ARCH TOOTH ALIGNMENT Refers to relationship of teeth in one arch to those in other. When two arches come in contact, as in mandibular closure,occlusal relationship of teeth is established. Arch Length :The distance of line that begins at distal surface of third molar extends mesially through all proximal contact areas around entire arch and end at distal surface of opposite third molar. For maxillary arch length is 128mm. For mandibular arch arch length is 126mm. Arch Width : is distance across the arch. The width of mandibular arch is slightly less than maxillary arch., thus when the arches occlude, each maxillary tooth is more facially positioned than occluding mandibular tooth. Because maxillary teeth are more facially positioned, normal occlusal relation is :  Buccal cusps of posterior mandibular teeth occlude along central fossa area of maxillary teeth.  Lingual cusps of posterior maxillary teeth occlude along central fossa of mandibular teeth. www.indiandentalacademy.com
  • CENTRIC / SUPPORTING AND NON CENTRIC / GUIDING CUSPS.  Buccal cusp of mandibular posterior teeth and lingual cusp of maxillary posterior teeth occlude with opposing central fossa. These cusps are called CENTRIC OR SUPPORTING CUSPS  These cusps are mainly important for keeping distance between maxilla and mandible. This distance supports the vertical facial height and is called VERTICAL DIMENSION OF OCCLUSION.  Buccal cusps of maxillary posterior teeth and lingual cusp of mandibular posterior teeth area called GUIDING OR NON CENTRIC CUSP / SHEARING CUSP  The major role of non-centric cusp is to minimize tissue impingment and maintain bolus of food on occlusal table for mastication. They also give stability to mandible so that when teeth are in full occlusion tight definite occlusal relationship results. This relationship of teeth in their maximum intercuspation is called Maximum Inter Cuspal Position. www.indiandentalacademy.com
  • BUCCOLINGUAL OCCLUSAL - CONTACT RELATIONSHIP  If imaginary line is extended through all buccal cusp tips of mandibular posterior teeth, bucco occlusal line is established. In normal arch this line flows smoothly and continuously, revealing general arch form. It also represents demarcation between inner and outer aspects of buccal cusps.  If imaginary line is extended through lingual cusps of maxillary posterior teeth, linguo occlusal line is observed. This line reveals general arch form and represents demarcation between outer and inner aspects of centric cusps.  If third imaginary line is extended through central develop mental grooves of maxillary and mandibular posterior teeth, the CF line is established. www.indiandentalacademy.com
  •  Once CF is established important relationship of proximal contain areas is noted. These areas are generally located slightly buccal to CF line which allows greater lingual embrasure area and smalled buccal embrasure area. During function, larger lingual embrasure area will act as major spillway for food bang masticated when teeth as brought in contact, majority of food is shunted to tongue, which is more efficient in returning food to occlusal table the is buccinator and perioral musculature.  To visualize buccolingual relationship of posterior teeth in occlusion appropriate imaginary lines must be matched. The BO line of mandibular occludes with CF line of maxillary teeth. Simultaneously the CO maxillary teeth occludes with CF line of mandibular teeth. www.indiandentalacademy.com
  • MESIODISTAL OCCLUSAL - CONTACT RELATIONSHIP Occlusal contacts occur when centric cusp contact opposing C.F. Viewed from facial, these cusps typically contact in one of 2 areas.  CF areas  Marginal ridge and embrasure areas. Contacts between cusp tips and CF area have been involved to grinding of pestle in mortar. When 2 unlike curved surfaces meet, only certain portions come into contact at given time, leaving other areas free of contact to act as spillways for substance being crushed. When mandible shifts during mastication, different areas contact, creating different spillways. This shifting increases efficiency of mastication. The second type of occlusal contact is between cusp types and marginal ridges. Marginal ridges are slightly raised convex areas at mesial & distal borders of occlusal surfaces that joins with inter proximal surface of teeth. The most elevated portion of marginal ridge is only slightly convex. Therefore his type of contact is best depicted by cusp tip contacting flat surface. In this relationship the cusp tip can penetrate through food easily and spillways are provided in all directions. When mandible moves laterally, actual contacts areas shifts, increase efficiency of cheweing stroke. Exact cusp tip is not solely responsible for occlusal contact. Circular area around true cusp tip with radius about 0.5mm provides contact area with opposing tooth surface. www.indiandentalacademy.com
  • OCCLUSAL RELATIONSHIPS OF POSTERIOR TEETH Class-I (i) Mesiobuccal cusp of mandibular first molar occludes in embrasure area between maxillary 2nd premolar and 1st molar. (ii) Mesiobuccal cusp of maxillary first molar is aligned directly over buccal groove of mandibular 1st molar. (iii) Mesiolingual cusp of maxillary first molar is situated in CF area of mandibular 1st molar. In this relationship each mandibular tooth occludes to its counterpart and adjacent mesial tooth. Contacts between molar occur on both cusp tips and fossae and on cusp tips and marginal ridges. Two variation in occlusal contact patterns can result with respect to marginal ridge areas. In some instances cusps contacts the embrasure area directly, resulting in 2 contacts on area of cusp tips. In other instance, cusp tip is positioned so that it contacts only one marginal ridge, resulting in only one contact on cusp tip. www.indiandentalacademy.com
  • Class II (i) (ii) (Iii) In some patient maxillary arch is large or advanced anteriorly or mandibular arch is small or positioned posteriorly. These conditions will result in mandibular 1st molar being positioned distal to class I molar relationship. Described as Class II molar relationship. Mesiobuccal cusp of mandibular 1st molar occludes in CF area of maxillary 1st molar. Mesiobuccal cusp of mandibular first molar is aligned with buccal groace of maxillary 1st molar. Distolingual cusp of maxillary first molar occludes in CF area of mandibular 1st molar. www.indiandentalacademy.com
  • Class-III Due to predominant growth of mandible. In this relationship, growth positions mandibular molar mesial to maxillary molars. (i) Distobuccal cusp of mandibular 1st molar is situated in embrasure between maxillary 2nd premolar and 1st molar . (ii) Mesiobuccal cusp of maxillary 1st molar is situated over embrasure between mandibular 1st and 2nd molar. (iii) Mesolingual cusp of maxillary 1st molar is situated in mesial pit of mandibular 2nd molar www.indiandentalacademy.com
  • OCCLUSAL RELATIONSHIP OF ANTERIOR TEETH  Maxillary anterior teeth are normally positioned labial to mandibular anterior        teeth. Both maxillary and mandibular anteriors are inclined to the labial, ranging 12-28º from vertical reference line. Incisal edges of mandibular incisors contacting lingual surfaces of maxillary incisors. These contacts commonly occur in lingual fossae of maxillary incisors approximately 4mm gingival to incisal edges. Purpose of anterior teeth is to guide mandible during various lateral movements. The anterior tooth contacts that provide guidance of mandible are called Anterior Guidance, Characteristics of anterior guidance are dictated by exact position and relationship of anterior teeth, which can be examined both horizontally and vertically. Horizontal distance by which maxillary anteriors overlap mandibular anteriors is called Horizontal over lap - Overjet. It is the distance between labial nasal edge of maxillary incisor and labial surface of mandibular incisor in ICP. Vertical overlap is distance between incisal edges of opposing anterior teeth which is approximately 3 - 5mm. Important function of anterior teeth is that of performing initial acts of mastication. Anterior teeth function to incise food when introduced in oral cavity. Anterior teeth also plays significant role in speech, lip support and aesthetics. www.indiandentalacademy.com
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  • ANDREW’S SIX KEYS TO NORMAL OCCLUSION Andrew’s during 1970s put forward six keys to normal occlusion. The six key are considered under the following headings: MOLAR INTERARCH RELATIONSHIP. The Mesio buccal cusp of upper first molar should occlude in the groove between mesial and medial buccal cusp of lower first molar. The mesio lingual cusp of upper first molar should occlude in the central fossa of lower first molar. The crown of upper first molar must be angulated so that distal marginal ridge occludes with the mesial marginal ridge of second molar MESIO DISTAL CROWN ANGULATION  The Second Key makes use of a line that passes along the long axis of crown through the most prominent part in the center of labial or buccal surface. This line is called long axis of clinical crown.  For occlusion to be considered normal, gingival part of long axis of crown must be distal to the occlusal part of the line. Different teeth exhibit different crown angulation. www.indiandentalacademy.com
  • LABIO LINGUAL CROWN INCLINATION  The crown inclination is determined from mesial or distal view. If the gingival area of crown is more lingualy placed than the occlusal area, it is referred to as positive crown inclinication. In case the gingival area of crown is more labially or buccally placed than the occlusal area it is referred to as negative crown inclinication  The Maxillary incisors exhibit a positive crown inclination while mandibular incisors show negative crown inclination. The maxillary and mandibular posteriors have negative crown inclination. ABSENCE OF ROTATION. Normal occlusion is characterized by absence of rotation. Rotated posteriors occupy more space in a dental arch. While rotated incisors occupy less space in dental arch. TIGHT CONTACTS For normal occlusion there should be tight contact between adjacent teeth. CURVE OF SPEE Normal occlusal plane according to Andrew’s should be flat with curve of spee not exceeding 1.5 mm. www.indiandentalacademy.com
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  •  VARIOUS MANDIBULAR MOVEMENTS AND     OCCLUSAL CONTACTS DURING THESE MOVEMENTS To this point only static relationships of posterior and anterior teeth have been discussed. Masticatory system is extremely dynamic. TMJ and associated musculature permit mandible to move in all 3 planes i.e. sagittal, horizontal, frontal. Along with these movements come potential tooth contacts. The term Eccentric have been used to describe any movement of mandible from ICP that result in tooth contact. Three basic eccentric movements are : (i) Protrusive (ii) Laterotrusive (iii) Retrusive www.indiandentalacademy.com
  •  (i) Protrusive Mandibular Movement : This movement occurs when mandible moves forward from ICP. Any area of tooth that contacts opposing tooth during protrusive movement is considered to be protrusive contact. In normal occlusal relationship the predominant protrusive contacts occur on anterior teeth, between incisal and labial edges of mandibular incisors and against lingual fossa areas and incisal edges of maxillary incisors. On posterior teeth protrusive movement causes mandibular centric cusps to pass anteriorly across occlusal surfaces of maxillary teeth. Protrusive posterior contacts occur between distal inclines of maxillary lingual cusps and mesial induces of opposing fossae and marginal ridges. Posterior protrusive contacts can also occur between mesial inclines of mandibular buccal cusps and distal inclines of www.indiandentalacademy.com opposing fossae and marginal ridges
  •  (ii) Laterotrusive Mandibular Movement  During lateral mandibular movement; right and left mandibular posterior teeth move across their opposing teeth in different directions. If for example, mandible moves laterally to left, left mandibular posterior teeth will move laterally across their opposing teeth. However, right mandibular posteriors will move medially across their opposing teeth.  Posterior teeth on left side during left lateral movement reveals that contacts can occur on 2 incline areas. One contact between inner inclines of maxillary buccal cusps and outer inclines of mandibular buccal cusps. Other contact is between outer inclines of maxillary lingual cusps & inner inclines of mandibular linqual cups. Both these contacts are called LATEROTRUSIVE  The term lingual to lingual Laterotrusive & buccal to buccal laterotrusive issued to differentiate those occuring between opposing lingual cusp from those occurring between buccal cusps. www.indiandentalacademy.com
  •  Working Contact :- Is commonly used for both these laterotrusive contacts  During same lateral movement, right mandibular posterior teeth are passing in medial direction across their opposing teeth. The potential sites for occlusal contacts are between inner inclines of mandibular buccal cusps. These are called Mediotrusive contacts. During left lateral movement most function occur on left side, therefore right side has been desiqnated as nonworking side . Thus these mediotrusive contacts are also called Nonworking contacts or Balancing contacts. www.indiandentalacademy.com
  •  (viii) Retrusive Mandibular Movement.:- Occurs when mandible moves posteriorly from 1CP.These movements are restricted by ligamentous structures. During retrusive movement mandibular buccal cusps move distally across occlusal surface of their opposing maxillary teeth. Areas of potential contact occurs between distal inclines of mandibular buccal cusps & mesial inclines of opposing fossae & marginal ridges. In maxillary arch retrusive contacts occurs between mesial inclines of opposing CF's & marginal ridges. www.indiandentalacademy.com
  • TYPES OF OCCLUSION  Normal Occlusion: Within frameworks of function occlusion (the correlation     between occlusion of teeth and movement of mandible) any mouth that has exhibited its ability to survive is considered normal. It is : Physiological Adaptive Physiological Occlusion: is state of equilibrium in which there is no pathology or other dysfunction of any component of somatognathic system occurring as result of occlusal activity, regardless of arrangement of teeth. Pathological Occlusion: It occurs when anything related to occlusal activity causes injury or impaired function somatognathic system. Adaptive Occlusion: It is between physiologic and pathologic occlusion. Structurally there is potential dysfunction, but it has not occurred to any great extent, e.g. persons having facets of wear has adaptive and require periodic examination but not treatment. Ideal Occlusion: A so called ideal occlusion can also be called, physiologic, functional or normal. When local occlusion exists. Somatognathic system usually functions in good health. In an ideal occlusion lateral forces are eliminated or minimized and occlusal forces are directed along long tooth and distributed equally on as many teeth as possible. Stamp cusps occlude against marginal ridges or into opposing occlusal fossa rather than interproximal embrasure. Usually there is full component of teeth in both arches. Each posterior tooth should have at least one antagonist to occlude & work against. www.indiandentalacademy.com
  •  The most ideal occlusion is mutually Protected occlusion in which posterior teeth protect anterior teeth during centric closure & anterior teeth protect posterior teeth in any movement or position away from centric contact position.  Disclusion: During protrusive sliding movements of mandible the incisors and canines act together in coupling effect as anteriors discludes in group function. In lateral excursions of mandible cuspids on working side act as discluders. Some times central and lateral incisors also help cuspids which is not always present but acceptable.  When determinants of occlusion and tooth arrangements are compatible, an occlusion can be considered stable. Stuart refers to tooth arrangement as an ORGANIZED OR ORGANIC OCCLUSION . www.indiandentalacademy.com
  • THERAPEUTIC OCCLUSION It is one in which arrangement of teeth and their opposing occlusal surfaces satisfies function and esthetic requirements while distributing the forces of occlusion over as many teeth during functions of mandible. Three most popular concepts of therapeutic occlusion are: (a) Fully balanced occlusion. (b) Unilateral balanced occlusion (c) Cusp-fossa occlusion (a) Fully Balanced Occlusion : It originated in denture construction, where it was felt that there should be bilateral equal contact of anterior and posterior teeth during CR as well as during protrusive and lateral excursive movement of mandible. The concept was advanced by Gpsi, McCollum. Gerber et al. It works for removable dentures but in natural dentition it doesn't offer 'position' for teeth or mandible that are god holding positions during centric closure. (b) Unilateral Balanced Occlusion : Advanced by Schuyler, Pankey, Mann & Ramfjord. It allows for contact of all teeth during centric position. With some freedom of movement anteroposteriorly. The centric slide of about 0.2 - 1mm at same vertical dimension is known as long centric. During lateral movement, disclusion occurs against canines and buccal cusps of maxillary and mandibular premolars and molars of working side. This is referred to as Group Function. There are no tooth contacts on non working during lateral excursive movement. Group function or posterior teeth with equally distributed occlusal forces on each involved tooth is very difficult to achieve but even if done, patient often develops occlusal awareness that leads to bruxism and occlusal disharmony. www.indiandentalacademy.com
  • (c) Cusp- Fossa occlusion :- Concept is based on gnathological principles of jaw function as well as physiological principles of somatognathic system.  During closure of posterior teeth into the intercuspation position, all stamp cusps occlude simultaneously into their opposing occlusion fossa. It is a distal limit occlusion in that the condyles & consequently cusp of mandibular teeth are functioning in their most distal positions.  At same time that stamp cusps make final contact in cusp fossa occlusion, condyles are positioned in their most retruded or unstrained position in their respective fossae. Since CO & CR tooth contacts are coincident there is not centric interference to cause occlusal slide & deviation of mandible. Patient close to CR occlusion where no single tooth carries more or less than its share of occlusal load. Occlusal forces are at an equilibrium throughout the mouth. During centric contact of posterior teeth in cusp-fossa occlusion anterior teeth do not touch having ideal space of .01mm betweem maxiallary & mandibular incisors & canines at CO. In this occlusion centric closure is positive closing position in which all posterior teeth contact simultanceously. The reciprocating contacts positioned as they are around fossa prevent tipping or rotation or teeth when occlusal forces are applied. www.indiandentalacademy.com
  • Mutually protected occlusion : When condyler & incisal guidance act together to disclude the posterior teeth. It is referred to as mutually protected occlusion. A cusp-fossa arrangement is functional occlusion. It is an artificial occlusion in which attention is directed specially to performance as differently from structure & appearance. eg. in cusp-fossa occlusal scheme a tooth is not always restored to its textbook image. It may have slightly altered shape to allow proper position of cusp- ridges & groves in function.  Anterior teeth protect the posterior & posterior teeth protect anterior during denture closure. Cusp-fossa occlusion can therefore be defined as mutually protected occlusion.  During working side movement cannot act as discluders of posterior teeth hence called canine protected occlusion, canine rise, canine disclusion & canine left.  This scheme is designed to eliminate lateral forces on posterior teeth. Because anterior teeth are lightly in contact in CO, posterior teeth support forces in CO protecting, periodontally vunerable anterior teeth from heavy clenching & chewing forces. Canine is structurally, neurologically & positionally well suited to support lateral forces in exclusion. So this type of occlusion also called Canine Guided Occusion. www.indiandentalacademy.com
  • BIO-MECHANICS OF OCCLUSION: Dental factors of occlusion. If dentition is functioning in health and form of dentition is esthetic, restoration of individual teeth requires duplication of existing occlusal form. Unless there is evidence of dysfunction such as occlusal trauma, excessive tooth wear, clearly unacceptable occlusal plane orientation or joint and muscle dysfunctioning occlusion should be considered normal restorations should be patterned to follow morphology of adjacent and opposing teeth. Anatomic factors important in the development occlusal patterns for restored tooth include the following :  Cusp Height  Cusp angle  Marginal ridge height  Contact area position  Contact area height  Fossa size  Triangular and oblique ridge height.  Triangular and oblique ridge directions  Groove depth and width  Groove direction www.indiandentalacademy.com  Faciolingual dimension of occlusal table
  •  Changes that should be particularly avoided include irregular adjacent      marginal ridge heights, changes in size and location of proximal contact area, widening or narrowing the buccolingual width of occlusal table, increase or decrese of cusp angulation, groove depth or angulation and location of occlusal contact areas. Common problems observed from such changes include the following Wedging of food interproximally during mastication that is often associated with irregular marginal ridge heights and missing contact areas Deflection of mandible from intercuspal position that is often associated with abnormally steep cusp heights or pre-mature occlusal contacts. Working cusp interferences that are often associated with abnormally steep cusp heights or improperly angled triangular or oblique ridges and grooves. Balancing cusp interferences associated with abnormally steep cusp heights Supra eruption and shifts in tooth position that must result from lack of occlusal and proximal contacts. www.indiandentalacademy.com
  • APPLIED ASPECTS 1. 2. 3. 4. 5. 6. The concepts of occlusion are established & recognized as guidline by all departments of dentistry. The need to maintain this relation is of almost importance. The salient features are :In small children with decidous dentition of nursing bottle caries or rampant caries is present then teeth get decalcified at very rapid rate & if unrestored for some time the other teeth migrate mesally the contact relation as well as integrity & occlusion of arch is lost. In children if we see that by age of 5-6 years the physiologic space have not yet develop that it is indicative of developing malocclusion. In cases of restoration of teeth using amalgam / composite /GIC/ Zinc phosphate etc. we should take care to check for high points, because these can lead to deviations in occlusion & discomfort to patient. Extraction of deciduous teeth unless & until its the last or only alternative, should not be done. This may lead to malocclusion because these decidous teeth act as guide for permanent teeth. If in mixed dentition period we see developing situation of crowding for permanent teeth then serial extraction should be considered. When giving patient fixed or removable prosthesis complete / partial than the points occlusion should be kept in mind & implemented during construction phase patient needing CD must not be given non-anatomic teeth or set up should not monoplane, just for ease of clinician. Multiple extractions without replacement should not be done as it may cause changes in vertical dimension of occlusion & may also lead to mutilated or collapsed occlusion. www.indiandentalacademy.com
  • OCCLUSION IN PROSTHODONTICS: Occlusion may be discussed from two view points Static Relations Dynamic Relations STATIC CONCEPT: Static relations in occlusion are those which occur in many possible contacts of teeth without interposition of food.Static Relations in occlusion include  Centric occlusion  Protrusive Occlusion  Right & left lateral occlusion  Intermediate occlusion www.indiandentalacademy.com
  • DYNAMIC CONCEPT: It is primarily concerned with opening & closing movements involved in mastication while static concept is concerned primarily with tooth contacts made at various positions. In this concept, jaw movements & tooth contacts that are made as teeth of one jaw guide over teeth of opposing jaw are not functional movements or contacts. This phase of occlusion is admitted to be controlled by TMJ, muscles & ligaments & teeth. Functional movements are the movements of lower teeth as they approach upper teeth in chewing cycle.The direction of closure is influenced by  TMJ  Occlusal form of teeth  Occlusal plane  Musculature (contraction & relaxation times of muscle)  Resistance of food & relative tolerance of supporting tissues. www.indiandentalacademy.com
  • TYPES OF COMPLETE DENTURE OCCLUSION: Balanced Occlusion Monoplane Occlusion Lingualized Occlusion I) BALANCED OCLUSION: DEFINITION: Simultaneous contacting of maxillary & mandibular teeth on right & left and in posterior & anterior occlusal areas in centric & accentric positions, developed to lessen or limit tipping or rotating of denture bases in relation to supporting structures. CHARACTERISTICS REQUIREMENTS OF BALANCED OCCLUSION:  All teeth of working side should glide evenly against opposing teeth.  No single tooth should produce any interference or disocclusion of other teeth.  There should be contacts in balancing side, but they should not interfere with smooth gliding movements of working side.  There should be simultaneous contact during protrusion. www.indiandentalacademy.com
  • IMPORTANCE OF BALANCED OCCLUSION:  Balanced occlusion is one of most important factors that affect denture stability. Absence of occlusal balance will result in leverage of denture during mandibular movement.  Sheppard stated that, “ENTER BOLUS, EXIT BALANCE” according to this statement, balancing contact is absent when food enters oral cavity. This makes us think that balanced occlusion has no function during mastication or as its role essential in complete denture.  Brewer reported importance of balanced occlusion. He reported that on an average normal individual makes masticatory tooth contact only for 10 mnts in one full day as compared to 4 hours of total tooth contact during other functions. So for these hours of tooth contact, balanced occlusion is important to maintain stability of denture. Hence, balanced occlusion is more critical during parafunctional movements. www.indiandentalacademy.com
  • GENERAL CONSIDERATIONS FOR BALANCED OCCLUSION: Ideal balanced occlusion can be achieved in cases with wide & large ridges & in complete dentures, with teeth arranged dose to ridge. Complete dentures that have teeth arranged away from the ridge & those that rest on wide ridges provide ideal balanced occlusion. Ideal balance can be achieved by arranging the teeth slightly on lingual side of crest of ridge. Arranging the teeth buccally will lead to poor balanced occlusion. If the teeth are set outside ridge the denture may elevate on one side during tooth contact stability of denture against these lever forces is called as LEVER BALANCE .Lever balance is different from balanced occlusion. It can be safely quoted that lever balance is also necessary for balanced occlusion. Complete denture should be designed in such a way that the forces of occlusion are centered anteroposteriorly in the denture. TYPES OF BALANCED OCCLUSION:  Unilateral balanced occlusion  Bilateral balanced  Protrusive balanced occlusion  Lateral balanced occlusion www.indiandentalacademy.com
  • i) UNILATERAL BALANCED OCCLUSION: This is type of occlusion seen on occlusal surface of teeth on one side when they occlude simultaneously with smooth, uninterrupted glide. This not followed during complete denture construction. It is more pertained to fixed partial dentures. ii) BILATERAL BALANCED OCCLUSION: This is type of occlusion that is seen when simultaneous contact occurs on both sides in centric & eccentric positions bilateral balanced occlusion helps to distribute the occlusal load evenly across the arch & therefore helps to improve stability of denture during centric eccentric or parafunctional movements. For minimal occlusal balance, there should be at least 3 points of contact on occlusal plane. More the number of contacts, better the balance Bilateral balanced occlusion can be protrusive or lateral balance. iii) PROTRUSIVE BALANCED OCCLUSION: This type of balanced occlusion is present when mandible in forward direction & occlusal contacts are smooth & simultaneous anteriorly & posteriorly. There should be at least three points of contact in occlusal plane. Two of these should be located posteriorly & one should be located in anterior region. This is absent in natural dentition. FACTORS THAT GOVERN PROTRUSIVE BALANCE:  Inclination of condylar path: This inclination recorded on patient represents the     path travelled by condyle in protrusion which is modified by combined action of all tissue in temperomandibular joint & ridges covered by recording bases. Angle of incisal guidance closes for patient. Angle of plane occlusion Compensating curves chosen www.indiandentalacademy.com condylar path for orientation with Cuspal height & inclination of posterior teeth.
  • iv) LATERAL BALANCED OCCLUSION:  In lateral balance, there will be a minimal simultaneous three point contact present during lateral movement of mandible.  Lateral balanced occlusion is absent in normal dentition, when a dentulous person with canine guided of all occlusion moves his mandible to right, there will be canine guided disocclusion of all these teeth. Even canine of opposite side will not have contact.  If this relationship is followed during teeth arrangement then denture will lose its stability due to lever action. To prevent this teeth should be arranged such that there is simultaneous teeth contact in balancing & working sides. www.indiandentalacademy.com
  • FACTORS THAT GOVERN LATERAL BALANCE:  Angle of inclination of condylar path on balancing side.  Angle of indication of plane of occlusion on balancing side and working side.  Compensating curve on balancing side and working side.  Buccal cusp heights or indication of teeth on balancing side.  Lingual cusp heights or indication on working side.  Bennett side shift on working side.  Steep cusps, produce more displacement of denture base that shallower or cuspless forms. Forces of occlusion acting on complete denture should be balanced from right to left and anterior to posterior direction.  An increase in any of above forces will affect balanced occlusion leading to compromised stability of denture.  If vertical overlap of anterior teeth is increased for aesthetic and phonetic reasons, then the horizontal overlap should adjusted to reduce the incisal guidance angle.  This adjustment provides space for free movement of ant-teeth. Without this adjustment there will be increased anterior interference leading to initial instability of denture base during protrusion. In long run, this may lead to resorption of residual alveolar ridge in anterior region. www.indiandentalacademy.com
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  • FACTOR INFUENCING BALANCED OCCLUSION Five basis factors that determine the balance of an occlusion are : Inclination of condylar path or condylar guidance Incisal guidance Orientation of plane of occlusion or occlusal plane Cuspal Angulation Compensating Curve www.indiandentalacademy.com
  • (i) Inclination of Condylar Path :  It is also called first factor of occlusion. This is only factor, which can be recorded from patient. It is registered using protrusive registration (i.e. patient is asked to protrude with occlusal rims. Interocclusal record material is Injected between occlusal rims in this position. The occlusal rims with inter occlusal record are transferred to articular. Since the occlusal rims are in protrusive relation, upper member of articulator is moved back to accommodate them. The interocclusal record is carefully removed and upper member is allowed to slide forward to its original position. The condylar guidance should be adjusted till upper member slides freely into position. It is transferred to articulator as condylar guidance.  Increase in condylar guidance will increase jar separation during protrusion. This factor of balanced occlusion can't be modified. All other four factors of occlusion should be modified to compensate effects of this factor. In patients with steep condylar guidance, incisal guidance should be decreased to reduce amount of jaw separation produced during protrusion and vice-versa. But it should be remembered that incisal guidance can't be made steep because it has its own effects www.indiandentalacademy.com
  • (ii) Incisal Guidance :  This is defined as "The influence of contacting surfaces of mandibular and maxillary anterior teeth on mandibular movements".  It is called 2nd factor of occlusion. It is determined by dentist and customized for patient during anterior try in. It acts as controlling path for movement of casts in an articulator. It should be set depending upon the desired overjet and overbite planned for the patient. If overjet is increased, the inclination of incisal guidance is decreased. If overbite is increased, then incisal inclination increases. The incisal guidance has more influence on posterior teeth than the condylar guidance. This is because the action of incisal inclination is closer to teeth than action of condylar guidance. During protrusive movements, incisal edge of mandibular anterior teeth move in downward and forward path corresponding to palatal surfaces of upper incisors. This is known as protrusive incisal path or incisal guidance. The angle formed by this protrusive path to horizontal plane is called as Protrusive Incisal path inclination or incisal guide angle.  Influences of shape of posterior teeth. If incisal guidance is steep, steep cusps or steep occlusal plane or steep compensatory curve is needed to produce balanced occlusion. In comple denture, the incisal guide angle should be as flat as possible. Hence, while arranging anterior teeth, for aesthetics, a suitable vertical overlap and horizontal overlap should be chosen to achieve balanced occlusion. Also, incisal guidance can't be altered beyond limits. The location and angulation of incisors are governed by various factors like aesthetics, function and phonetics etc. www.indiandentalacademy.com
  • (iii) Plane of Occlusion or occlusal plane :   It is defined as an imaginary surface which is related anatomically to cranium and which theoretically touches incisal edges of incisors and tips of occluding surface of posterior teeth. It is not plane in true sense of word but represents mean curvature of surface. It is established interiorly by height of lower canine, which nearly coincides with commissar of mouth and posteriorly by height of retromolar pad. It is usually parallel to traqus line or camper's line. It can be slightly altered and its role is not as important as other factors. Tilting the plane of occlusion beyond 10° is not advisable. (iv) Compensating Curve :     It is defined as "the anteroposterior and lateral curvature in alignment of posterior and lateral curvature in alignment of occluding surfaces and incisal edges of artificial teeth which are used to develop balanced occlusion." It is important factor for establishing balanced occlusion. It is determine by inclination of posterior teeth and their vertical relationship to occlusal plane. The posterior teeth should be arranged such that their occlusal surfaces from a curve. This curve should be in harmony with movements of mandible guided posteriorly by condylar path. A steep condylar path requires sleep compensatory curve to produce balanced occlusion. If shallow compensating curve is given for same situation, there will be loss of balancing molar contacts during protrusion. There are 2 types of compensating curves namely : Anteroposterior curves Lateral Curves www.indiandentalacademy.com
  •  ANTEROPOSTERIOR COMPENSATING CURVES : These are compensatory curves running in anteroposterior direction. They compensate for curve of spee seen in natural dentition.  Compensating Curve for Curve of Spee : Defined as Anatomic Curvature of occlusal alignment of teeth beginning at tip of lower canine and following buccal cusps of lower canine and following buccal cusps of natural premolars and molars,continuing to anterior border of ramus as described by Grafton. It is an imaginanory curve joining buccal cusps of mandibular posterior teeth starting from canine passing through head of condyle. It is seen in natural dentition and should be reproduced in a C.D. The significance of this curve is that, when patient moves his mandible forward, posterior teeth set on this curve will continue to remain in contact. If teeth are not arranged according to this curve, there will be dis-occlusion during protrusion of mandible (Christensens Phenonenon).  LATERAL COMPENSATING CURVES : These curves run transversely from one side of arch to other the following curves fall in this category.  Compensating Curve for Monson Curve : Monson’s curve is defined as 'The curve of occlusion in which each cusp and incisal edge touches or conforms to segment of a sphere of 8 inches in daimeter with its centre in region of Glabella." This curve runs across palatal and buccal cusps of maxillary molars. During lateral movements of mandibular lingual cusps on working side should slide along inner inclines of maxillary buccal cusp. In balances side the mandibular buccal cusps should contact inner inclines of maxillary palatal cusp. Thiswww.indiandentalacademy.com relationship forms a balance. Only if teeth are set following the monsoons curve there will be lateral balance of occlusion.
  •  Compensating Curve for Anti-Monson or Wilsons Curve : Wilsons curve is defined as " A curve of occlusion which is convex upwards". This curve run and opposite to direction of monsoons curve this curve is followed when 1st premolars are arranged. The premolars are arranged according to this curve so that they do not produce any interferance to lateral movements.  Reverse Curve : "A curve of occlusion which is transverse cross section conforms to line which is convex upward." It was originally developed to improve stability of denture. It is explained in relation of mandibular posterior teeth. The reverse curve was modified by Max Pleasure to for pleasure curve.  Pleasure Curve : "A curve of occlusion which is transverse crosssection conforms to line which is convex upward except for last molars. It was proposed by Max Pleasure. He proposed this curve to balances occlusion and increase stability of denture. Here the first molar is horizontal and 2nd premolar is bucally tilted. The 2nd molar independently follows the anteroposterior compensating curved and lingually tilted. This curve runs from palatal cusp of 1st premolar to distobuccal cusp of 2nd molar. The 2nd molar gives occlusal balance and 2nd premolar gives lever balance. www.indiandentalacademy.com
  • (V) CUSPAL ANGULATION :     Cusp angle is defined as " The angle made by average slope of cusp with cusp plane measured mesiodstally or buccolingually." Cusps on teeth or inclination of cuspless teeth are important factors that modify effect of plane of occlusion of compensating curves. The mesiodistal cusps lock occlusion such that repositioning of teeth doesnot occur due to settling of base. In order to prevent locking occlusion, mesiodistal cusps are reduced during occlusal reshaping. In absence of mesiodistal cusps, buccolingual cusps are considered factor for balanced occlusion. In cases with shallow overbite, cuspal angle should be reduced to balance incisal guidance. This is done because jaw separation will be less in cases with overbite. Teeth with sleep cusp will produce occlusal interference in these cases. In case with deep bite, jaw separation is more during protrusion teeth with high cuspal inclines are reguided in these cases to produce posterior contact during protrusion. www.indiandentalacademy.com
  • MONOPLANE OR NON-BALANCED OCCLUSION It is an arrangement of teeth with form or purpose. It includes the following concepts of occlusion:  Spherical theory  Organic occlusion  Occlusal balancing ramps for protrusive balance  Transographics General Considerations The following point have to be considered while using a non-balanced occlusion for a denture:  Opposing artificial teeth should not contact when the jaws are in eccentric relation, because it may give destabilizing forces to the basal seat area. The architecture of the basal seat does not allow tooth contact when the mandibule is in eccentric position.  Tooth contact should occur only when the mandible is in centric relation to the maxilla.  The patient should be encouraged to repeat the mandibular movements till there is no discomfort in the centric relation. www.indiandentalacademy.com
  • LINGUALIZED OCCLUSION:  Lingualized occlusion, one of the more popular occlusal schemes was introduced by Alfred Gysi in 1927. The basic concepts of lingualized occlusion were suggested by Payne. It was Earl pound who first used the term “lingualized occlusion”.  This occlusal scheme was introduced as an attempt to maintain the esthetics and food penetration advantages of the anatomic form while maintaining the mechanical freedon of the non-anatomic forms. Indications  In a situation where the patient places a high priority on aesthetics but the oral condition requires the use of non-anatomic teeth, e.g. severe alveolar ridge resorption, Class II ridge relationship.  When a complete denture opposes a removable partial denture.  Parafunctional habits. Advantages Payne stated the advantages as:  Can be adapted to different types of ridges  A solid maximum intercuspation  Absence of deflective occlusal contact in lateral excursions  Esthetic arrangement of teeth  Balanced articulation can be achieved. www.indiandentalacademy.com
  • Types of Tooth Forms used  Semianatomic teeth  Non-anatomic teeth  Myerson lingualized integration tooth molds. Principles of Lingualized Occlusion  Anatomic teeth are used for the maxillary denture. Teeth with prominent lingual cusps are helpful.  The buccal cusps are raised above the occlusal plane. They have no functional role. They improve esthetics and help prevent cheek biting.  Non-anatomic or semi-anatomic teeth are used for the mandibular denture. A narrow occlusal table is preferred where severe residual ridge resorption has occurred.  Modification of the mandibular posterior teeth is accomplished using selective grinding.  When the patient moves into a working relationship, the lingual cusp of the maxillary teeth functions against the mandibular teeth (hence the term lingualized occlusion.) www.indiandentalacademy.com
  • CONCLUSION :  To understand occlusion in broadest sense, it is necessary to consider, in addition to TMJ articulation, muscles and teeth, some of neurobehavioral mechanism that gives meaning to presence and function of masticatory system. Although many of neural interactive mechanisms between occlusion & thoughts, sensibleness and emotions are complex and often intermediate, it is possible to suggest strategies that could account for variety of responses that occur in function and parafunction.  The obvious strategy to compensate for wear of proximal contact areas is mesial migration of teeth, and strategy to compensate of for wear of occlusal surfaces is explain of teeth. The strategy for regulating the contraction of jaw elevators to achieve normal resting position of mandible with a small interocclusal space is postural refresh. The overall strategy for motivation to have access to muscle of mastication might be to provide 'drive' for ingestive processes, specially during early stages of devlopment of masticatory system and maturation of nervous system. Swallowing in fetal life, suckling in newborn and chewing in young infant.  Functional disturbances of masticatory system may involve psycho physiological mechanisms that are related to tech and their functions. Therefore occlusal interferences to function or parafunction may then involve more than simply contact relations of teeth they may involve psycho physiological mechanisms of human behavior as well. www.indiandentalacademy.com
  • REFERENCES  The Glossary of Prosthodontic Terms 8th Ed. Prostho-dent 2005; 94 : 7-92.  Stanley Jablonski. Jablonskis Dictionary of Dentistry. Ist Ed; 2005. A.I.T.B. S. Publishers and Distributors: 556  Mayor M. Ash, Stanley J. Nelson. Wheeler’s Dental Anatomy Physiology and Occlusion, 8th Ed. Saunders 2003: 437-488.  Peter E. Dawson; Classification system for occlusion that relates maximal intercuspation to position and condition of tempromandibular joints. J. Prosthel Dent 1996; 75(1) : 60-6.  Mac Donald J.W.C. Relatioship between occlusal contacts and jaw closing muscle activity during tooth clenching. J Prosthet Dent 1984: 52(5): 718-29.  Graf H., Dent M., Zander. HA. Tooth contact patterns in mastication. J Prosthet Dent 1963 ; :1055-66  Santos J.S. Occlusion Principles and concepts, 2nd Ed. A.I.T.Bs Publishers and Distributers : 117-33.  Balaji S.I. Orthodontia the Art and Science 2nd Ed. Arya publishing house : 45-58. www.indiandentalacademy.com
  •         Moyers RE. Handbook of orthodontics 4th Ed. Year book Medical publishers : 126-140. Tand S. Textbook of Pedodontics 1st Ed. Paras Publishing House :117-19 Okeson J.P. Management of Tempromandibular Disorders and Occlusion, 8th Ed. Saunders 2003: 437-88. Parker M.W. The significance of occlusion in restorative dentistry. Dental clinics of North America 1993; 37(3) : 341-51. Warner S. Biomechanics of Occlusion and articulators. Dental Clinics of North America 1995; 39:257-84. Boucher C.O. Occlusion in Prosthodontics. J. Prosthel Dent J 95: 3(5) : 633-56. Nallaswamy D. Text book of Prothodontics. 1st Ed. Jaypee Brothers Medical publishers : 181-198. George B. Textbook of complete Denture Prosthodontics. Ist Ed. CBS Publishers and Distributors: 232-32. www.indiandentalacademy.com
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