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OCCLUSION IN COMPLETE DENTURES

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OCCLUSION IN COMPLETE DENTURES

  1. 1. BY:- DR PRANAV VERMA PG 1ST YEAR
  2. 2. • INTRODUCTION • CONCEPTS OF COMPLETE DENTURE OCCLUSSION • BALANCED OCCLUSSION • LINGUALIZED OCCLUSSION • MONOPLANE OCCLUSSION • DISCUSSION OF TEETH ARRANGEMENT UNDER VARIOUS OCCLUSSAL SCHEMES • SUMMARY • REFERENCES
  3. 3. INTRODUCTION • DEFINITIONS OF OCCLUSION • HISTORY • DEVELOPMENT OF DENTAL OCCLUSION • BIOMECHANICS OF OCLLUSION • DIFFERENCES BETWEEN NATURAL AND ARTIFICIAL OCCLUSION • REVIEW OF LITERATURE
  4. 4. INTRODUCTION OCCLUDE MEANS TO “CLOSE” “The static relationship between the incising or masticating surfaces of the maxillary or mandibular teeth or tooth analogues” GPT 8 “The act or process of closure or of being closed or shut off.” “Any contact between the incising or masticating surfaces of the maxillary and mandibular teeth.” Occlusion is an important factor which governs the retention and stability of the complete denture in vivo.
  5. 5. TERMINOLOGIES:- CENTRIC OCCLUSION:- The occlusion of opposing teeth when the mandible is in centric relation. This may or may not coincide with the maximal intercuspal position gpt 8 ECCENTRIC OCCLUSION:- an occlusion other than centric occlusion gpt8 MAXIMUM INTERCUSPATION:- complete intercuspation of opposing teeth independent of condylar positions gpt8 EXCURSIVE MOVEMENT:- movement occuring when mandible moves away from maximum intercuspation. gpt8 BALANCING SIDE OR NON WORKING SIDE:- the side of mandible which moves during median line during lateral excursions. BALANCING INTERFERENCES:- undesirable contacts occuring on balancing side during lateral movements
  6. 6. HISTORY Mammals evolved from a group of “mammal-like reptiles” about 280 - 190 million years ago. Reptiles cannot bring their upper and lower teeth together and cannot chew; their teeth cannot move because they are ankylosed. But by the time the earliest known mammal had evolved, these now had two sets of dentitions, and the upper and lower teeth could be occluded. Diphyodonty (one replacement set, i.e. two dentitions) probably evolved as a result of the increasing efficiency of the dentition created by the use and wear of teeth that would shear against each other. There is no point in producing a succession of such inefficient dentitions, as every newly erupted molar, because of its high unworn cusps, would have disrupted the smoothly efficient shearing edges which are created by attrition
  7. 7. Early wear of teeth in a gorilla Early wear of teeth in a human who lived about 10,000 years ago. The wear has produced a sharp edge of enamel on the first molar, which is very efficient for shearing and cutting of coarse food, and the flatter occlusal surface allows for efficient grinding. This person was a coastal-dweller, and lived on a variety of foods, including fish and crustaceans. The other teeth still have enamel occlusal surfaces.
  8. 8. A deciduous dentition also helps to solve the problem of providing a child with a most effective masticatory apparatus appropriate to their needs at that time, and consistent with the space available in the jaws. The potential functional weakness of a transition period is minimised by the sequence of events: when the central incisors are lost, the deciduous lateral incisors and canines can be used to incise food, whilst loss of the deciduous molars does not prevent crushing and grinding because the first permanent molars are already in place. The allied development of a gomphosis (periodontal ligament type attachment) allows the position of each tooth to be adjusted after eruption, in response to forces produced during chewing, so that it normally ends up in the most efficient position.
  9. 9. DEVELOPMENT OF DENTAL OCCLUSION Term occlusion is derived from the Latin word, “occlusio”; defined as the relationship between all the components of the masticatory system in normal function, dysfunction and parafunction. An ideal occlusion is the perfect interdigitation of the upper and lower teeth, which is a result of developmental process consisting of the three main events, jaw growth, tooth formation and eruption Occlusal development can be divided into the following development periods: • Neo-natal period. (lasts upto 6 months after birth) • Primary dentition period. (From around the 6th month to 6 years) • Mixed dentition period. (Around 6 years- 12 years) • Permanent dentition period (12 years onwards)
  10. 10. CONSISTENCY IN PATTERN DEVELOPMENT Leighton has shown that the upper anterior gum pad (intercuspid width) is typically wider than the lower anterior pad, and the upper anterior gum pad protrudes (overjet) about 5 mm relative to the lower anterior gum pad.“ The upper anterior gum pad usually overlaps (overbite) the lower anterior pad by about 0.5 mm. In the first 6 months of postnatal life, there is marked palatal width increase, and the overjet decreases rapidly. PRIMARY DENTITION TERMINUS By 3 years of age, the occlusion of 20 primary teeth is usually established. The relationship of the distal terminal planes of opposing second primary molar teeth can be classified into one of three categories • FLUSH TERMINAL PLANE • DISTAL STEP • MESIAL STEP
  11. 11. THE PERMANENT DENTITION
  12. 12. In September of 1972, Lawrence F Andrews published an article in the AJO-DO titled The Six Keys to Normal Occlusion  Key I – Molar Relationship  Key II – Crown Angulation (tip)  Key III – Crown Inclination (torque)  Key IV – Rotation  Key V – Tight Contacts  Key VI – Curve of Spee KEY 1 According to Andrews’ definition, normal occlusion exists when the mesiobuccal cusp of the maxillary first permanent molar occludes in the groove between the mesial and middle buccal cusps of the mandibular first permanent molar (Figure 3, also known as Class I dental occlusion). ADREWS KEYS TO NORMAL DENTAL OCCLUSION PRESENT IN NATURAL DENTITION
  13. 13. KEY 2 The gingival portion of the crowns of all teeth is more distal than the incisal or occlusal portion of the crowns. The long axis of all crowns of the teeth (with the exception of the molars) is considered the main mid-development ridge of the facial surfaces of the teeth. The long axis of the crown of the molar teeth is considered to be the buccal groove and its extension to the gingiva
  14. 14. KEY III – CROWN INCLINATION This refers to the labio-lingual axial inclination of the anterior teeth and bucco-lingual axial inclination of the posterior teeth. KEY IV – ROTATION The fourth key to optimal occlusion is absence of tooth rotations In upper incisors, the gingival portion of the crown’s labial surface is lingual to the incisal portion. In all other crowns, including lower incisors, the gingival portion of the labial or buccal surface is labial or buccal to the incisal or occlusal portion.
  15. 15. KEY V – TIGHT CONTACTS There should be no spaces between the teeth. Contact points should abut unless a discrepancy exists in a mesiodistal crown diameter. KEY VI – CURVE OF SPEE The depth of the curve of Spee should be fairly flat ranging from 0.5mm to 1.5mm at its deepest point. An average curve of Spee is 1mm.
  16. 16. BIOMECHANICS OF OCCLUSION
  17. 17. DIFFERENCES BETWEEN NATURAL & ARTIFICIAL OCCLUSION NATURAL TEETH ARTIFICIAL TEETH Natural teeth function independently & each individual tooth disperses the occlusal load. Artificial teeth functions as a group & the occlusal loads are not individually managed. Malocclussion can be non-problematic for long time Mal occlusion poses immediate drastic problems Non-vertical forces are well tolerated Non-vertical forces damages the supporting tissues Incising does not affect the posterior teeth. Incising will lift the posterior part of the denture. The second molar is the favoured area for heavy mastication and better Heavy mastication over the second molar area can tilt or lift the denture base
  18. 18. NATURAL TEETH ARTIFICIAL TEETH Bilateral balance is not necessary and usually considered as hindrance. Bilateral balance is mandatory to produce stability of denture. Proprioceptive impulses give feedback to avoid occlusal prematurities. This helps patient to have habitual occlusion away from centric relation There is no feedback and denture rests in centric relation . Any prematurities in this position can shift the base
  19. 19. REVIEW OF LITERATURE In 1972 Beck listed the uses of different tooth forms into contemporary occlusal schemes out of which five were of the nature of a balanced articulation concept and five of a nonbalanced articulation. The concept of balanced articulation can be traced back to Gysi who introduced the 33 degree cusp form teeth. This anatomic tooth form was followed by a 30 degree posterior 9 tooth form introduced by Pilkington and Turner . These teeth mathematically designed , were the favorite for clinicians to develop a balanced occlusal scheme. Gysi in 1927 proposed the concept of lingualized articulation. His initial publication was followed by numerous authors' propsing modifications to this concept. Payne in 1941 reported on Farmer's posterior teeth setup that utilised 30 degree cusp form teeth that were reshaped to the requirementst of lingualized articulation.
  20. 20. Following this period Non-anatomic posterior tooth forms have been introduced. These teeth favor concepts which utilize non-balanced articulation. Sears was one of the greatest proponents of this concept. Although initially these tooth forms were not preferred, since then modified non-anatomic tooth forms have been introduced which are more extensively used today. Pound proposed a non-balanced articulation in which importance was given to the position of the anterior teeth to preserve the phonetics and a lingualised occlusal scheme to allow increased denture efficiency and stability in the chewing cycle Jones in 1972 proposed the concept of monoplane articulation This concept includes a non-anatomic occlusal scheme with a few specific modifications. With the introduction of 0 teeth, the monoplane scheme has become popular in certain patients requiring complete dentures. Bonwill in 1858 described the equilateral triangle theory based on a points of occlusal balance.
  21. 21. MacMillan based on his studies suggested a shift from bilateral balanced occlusion to unilateral balanced occlusion while restoring both natural and prosthetic dentitions. He observed that bilateral balanced occlusion commonly did not exist in nature. His evidence was based on the evaluation of “various types of masticatory excursions of lower animals.” Swoope in 1990 studied the effect of cusp form & occlusal surface area on denture base deformation Nimo in 1994 described method for developing balancing ramps in complete dentures with non anatomic teeth
  22. 22. CONCEPTS OF OCCLUSSION Unlike natural teeth, the artificial teeth act as a single unit. Hence, there should minimum of three contact points ( usually one anterior and two posterior) for the even distribution and stabilization of denture at any position of mandible. Complete denture occlusion varies with type of the teeth selected. Anatomic teeth should be arranged in balanced occlusion and non anatomic teeth should be arranged in monoplane occlusion ALL THE OCCLUSAL FORMS SHOULD HAVE TRIPD CONTACT IN CENTRIC RELATION All the occlusal forms are based on different concepts of occlusion Which are:- : spherical concept of occlusion : organic concept of occlussion : neutrocentric concept of occlusion
  23. 23. SPHERICAL CONCEPT OF MONSON Proposed by Dr. George S. Monson in 1920. An ideal curve of occlusion in which each cusp and incisal edge touches the surface of an imaginary sphere 8 inches in diameter.
  24. 24. ORGANIC CONCEPT OF OCCLUSION Here, existing shape of the teeth are altered to have the cusps suitable for the patient comfort and harmony during movement of mandible during function.  Movement of the condyle determines the direction of the ridges and grooves of the teeth  And mandibular movements determines theother factors like cusp height, fossa, depth of the fissure and concavity f the lingual surface. In organic or organized occlussion the aim is to relate the occlusal surfaces of the teeth so that teeth are in harmony with the muscles and joints during function NEUTROCENTRIC CONCEPT OF OCCLUSION Here the plane of occlusion should be flat and parallel to the residual alveolar ridge. There is no antero-posterior, bucco lingual inclines for the posterior teeth. ( like monoplane occlusion) Term neutrocentric denotes an occlusion that eliminates the anteroposterior and buccolingual inlines to direct the forces to posterior teeth
  25. 25. SEARS AXIOMS OF COMPLETE DENTURE OCCLUSION SEARS published the following factors to be considered that helps plan the complete denture occlusion: • Smaller the area of the occlusal surface, lesser the occlusal load going to supporting tissue i.e. bone. • Vertical force in tilted occlusal surface produce non-vertical force on the denture. • Vertical force acting outside the ridge crest will produce tipping of the denture. • Vertical forces on the denture base lyin over the resilient tissues will produce lever forces on the denture
  26. 26. OCCLUSAL SCHEMES REQUISITES TO FULLFILL THE REQUIREMENTS Occlusal schemes has three requisites 1. Incisive units 2. Working units & 3. Balancing units INCISIVE UNITS Includes all four incisors a) Sharp units for increased incising efficiency b) Units should not contact during mastication, they should only contact during protrusion c) Shallow incisal guidance d) Increased horizontal overlap to avoid interference during settling ( the mandibular denture may slide anteriorly as it settles) WORKING UNITS a) Cusps for good cutting and grinding efficiency b) Smaller buccolingual width to decrease the occlusal load transferred to the tissues c) Group function at the end of the chewing cylce during eccentric position
  27. 27. d) The occlusal load should be directed to the anteroposterior centre of the denture e) The plane of occlusion should be parallel to the mean foundation plane of the ridge BALANCING UNITS a) Second molars should be in contact during protrusive action b) They should have contact with the working side at the end of the chewing cycle c) Smooth gliding contacts should be available fo uninterfered lateral and protrusive movements.
  28. 28. “Occlusal scheme is defined as the form and the arrangement of the occlusal contacts in natural and artificial dentition.” The pattern of occlusal contacts between opposing teeth during centric relation and functional movement of the mandible will be determined by the occlusal schemes. The quantity and the intensity of these contacts determine the amount and the direction of the forces that are transmitted through the bases of the denture to the residual ridges. That is why the occlusal scheme is an important factor in the design of complete denture prosthesis.
  29. 29. OCCLUSAL SCHEMES HAVE BEEN CLASSIFIED INTO:  NEUTROCENTRIC OCCLUSION  LINGUALIZED OCCLUSION  NON ANATOMIC OCCLUSION (MONOPLANE OCCLUSION WITH BALANCE)  LINEAR OCCLUSION  BALANCED OCCLUSION
  30. 30. BALANCED OCCLUSION : “The bilateral, simultaneous, anterior and posterior occlusal contact of teeth in centric and eccentric positions .” It is not seen in natural dentition. Characteristic requirements of balanced occlusion: • All the teeth of the working side (central incisor to second molar) should glide evenly against the opposing teeth. • No single tooth should produce any interference or disocclusion of the other teeth. • There should be contacts in the balancing side, but they should not interfere with the smooth gliding movements of the working side. There should be simultaneous contact during protrusion
  31. 31. IMPORTANCE OF BALANCED OCCLUSION : Balanced occlusion is one of the most important factors that affect denture stability, absence of occlusal balance will result in leverage of the denture during mandibular movement. Sheppard stated that, “Enter bolus, Exit balance” according to this statement, the balancing contact is absent when food enters the oral cavity. This makes us think that balanced occlusion has no function during mastication; hence, it is not essential in a complete denture, but this is not true. On an average, a normal individual makes masticatory tooth contact only for 10 minutes in one full day compared to 4 hours of total tooth contact during other functions. So, for these 4 hours of tooth contact, balanced occlusion is important to maintain the stability of the denture. Hence, balanced occlusion is more critical during parafunctional movements
  32. 32. GENERAL CONSIDERATIONS FOR BALANCED OCCLUSION
  33. 33. TYPES OF BALANCED OCCLUSION Occlusal balance or balanced occlusion can be classified as Follows • UNILATERAL BALANCED OCCLUSION • BILATERAL BALANCED OCCLUSION • PROTRUSIVE BALANCED OCCLUSION • LATERAL BALANCED OCCLUSION UNILATERAL BALANCED OCCLUSION: This is a type of occlusion seen on occlusal surfaces of teeth on one side when they occlude simultaneously with a smooth, uninterrupted glide. This is not followed during complete denture construction. It is more pertained to fixed partial dentures.
  34. 34. BILATERAL BALANCED OCCLUSION : This is a type of occlusion that is seen when simultaneous contact occurs on both sides in centric and eccentric positions. Bilateral balanced occlusion helps to distribute the occlusal load evenly across the arch and therefore helps to improve stability of the denture during centric, eccentric or parafunctional movements. For minimal occlusal balance, there should be at least three points of contact on the occlusal plane. More the number of contacts, better the balance. Bilateral balanced occlusion can be protrusive or lateral balance.
  35. 35. PROTRUSIVE BALANCED OCCLUSION : This type of balanced occlusion is present when mandible moves in a forward direction and the occlusal contacts are smooth and simultaneous anteriorly and posteriorly. There should be at least three points of contact in the occlusal plane. Two of these should be located posteriorly and one should be located in the anterior region. This is absent in natural dentition.
  36. 36. LATERAL BALANCED OCCLUSION Minimal 3 point contact during lateral movement of the mandible. Absent in normal dentition. Factors : • Angle of inclination of condylar path. • Angle of incisal guidance. • Angle of inclination of plane of occlusion • Compensating curves. • Buccal & lingual cusp height. • The Benett side shift on the working side
  37. 37. CONCEPTS PROPOSED TO ATTAIN BALANCED OCCLUSION
  38. 38. NINE FACTORS GOVERNING THE ARTICULATION ARE CALLED AS “HANAU’S LAWS OF ARTICULATION”  Horizontal condylar guidance  Compensating curve  Protrusive incisal guidance  Plane of orientation  Buccolingual inclination of the tooth axis  Sagittal condylar pathway  Sagittal incisal guidance  Tooth alignment  Relative cusp height
  39. 39. Hanau later condensed these nine factors and formulated five factors which are commonly known as Hanau’s Quint: -Condylar Guidance -Incisal Guidance -Compensating curves -Relative Cusp Height -Plane of Orientation of occlusal plane
  40. 40.  Trapozzano reviewed Hanau’s five factors and decided that only three factors were concerned with balanced occluson.  He eliminated the plane of orientation and compensating curve inclination TROPOZZANO’S CONCEPT
  41. 41. BOUCHER’S CONCEPT Carl O Boucher analyzed Trapazzano’s work and stated his own concepts and ideas as follows:-  There are three fixed factors of balanced occlusion, the orientation of the occlusal plane, the incisal guidance and the condylar guidance.  The angulation of certain cuspal inclines is more important than the height of the cusps.  Boucher felt that the compensatory curve is important since it helps in increasing the effective height of the cusps without changing the form.  Boucher’s disagreed with Trapazzano that the occlusal plane could be located at various heights to favour a weaker ridge and recommended that the plane be orientated exactly as when natural teeth were present.
  42. 42. LOTTS’S CONCEPT He clarified the laws of occlusion by relating them to the posterior separation that is the resultant of the guiding factor. He stated the laws as follows  The greater the angle of condyle path, the greater is the posterior separation.  The greater the angle of overbite, the greater is the separation in the anterior region and the posterior region
  43. 43.  The greater the separation of the posterior teeth the greater or higher must be the compensating curve.  Posterior separation beyond the balancing abiltiy of the compensating curve can be balanced by the introduction of the plane of orientation.
  44. 44.  The greater the separation of the teeth, the greater must be the height of the cusps of posterior teeth.  He simplified the hanau’s quint using following chart
  45. 45. BERNARD LEVIN’S CONCEPT • He believed that it was not necessary to consider plane of occlusion because it was not very useful practically. • He also stated that plane of occlusion can be altered 1-2mm to increase the stability of denture He named the other four factors as “QUAD” which are as follows:-  The condylar guidance is fixed and is recorded from the patient.  The incisal guidance is usually obtained from patients esthetic and phonetic requirements  The compensating curve is the most important factor in obtaining occlusal balance.  Cusp teeth have the inclines necessary for balanced occlusion but nearly always used with a compensating curve
  46. 46. FACTORS INFLUENCING BALANCED OCCLUSION (1) INCLINATION OF THE CONDYLAR PATH. (2) INCISAL GUIDANCE. (3) ORIENTATION OF THE PLANE OF OCCLUSION (4) CUSPAL ANGULATION. (5) COMPENSATING CURVE.
  47. 47. 1). CONDYLAR GUIDANCE Recorded from the patient using protrusive registration. The interocclusal records are transferred to the articulator and then accomodated to glide freely into position. Mechanics: Increase in the condylar guidance will increase the jaw separation during protrusion. This factor cannot be modified. So in patients with steep condylar guidance incisal guidance is decreased to prevent the posterior jaw separation.
  48. 48. Components of condylar guidance a).Horizontal condylar guidance-guides the forward movement for protrusive balance. b).Lateral condylar guidance-guides the sideward or lateral movement of the mandible.
  49. 49. INCISAL GUIDANCE Defined as “ influence of contacting surfaces of maxillary and mandibular teeth during mandibular movements” Component of incisal guidance: 1). Horizontal component 2). Vertical component
  50. 50. • It is the second factor of balanced occlusion. • It is determined by dentist during anterior try in. • It should be set according to desired overjet and overbite of the patient. During protrusive movements movement of mandibur teeth is guided by the palatal surfaces of the maxillary teeth which is called incisl guidance or protrusive path.
  51. 51. 3). PLANE OF OCCLUSION OR OCCLUSAL PLANE- Defined as “An imaginary surface which is related anatomically to the cranium and which theoretically touches the incisal edges of the incisors & the tips of the occluding surfaces of posterior teeth. It represents the mean curvature of the surface. Established anteriorly by height of lower canine and posteriorly by height of retromolar pad. Parallel to campher’s line & tilting of the plane >10o is not advisable
  52. 52. 4). COMPENSATING CURVE “The anterioposterior and lateral curvatures in the alignment of the occluding surfaces and incisal edges of artificial teeth which are used to develop balanced occlusion” Determined by inclination of posterior teeth and their vertical relationship to occlusal plane Two types a) anteroposterior compensating curve b) Lateral compensative curve
  53. 53. ANTERIOPOSTERIOR COMPENSATING CURVES CURVE OF SPEE “ Anatomic curvature of the occlusal alignment of teeth beginning at the tip of lower canine and following the buccal cusps of the natural premolars and the molars, continuing to the anterior border of the ramus” as described by Graf Von Spee
  54. 54. SIGNIFICANCE - WHEN THE PATIENT MOVES HIS MANDIBLE FORWARD, THE POSTERIOR TEETH SET ON THIS CURVE WILL CONTINUE TO REMAIN IN CONTACT.THUS AVOIDING DISOCCLUSION
  55. 55. Posterior teeth separation when the curve of spee not incorporated Incorporating the curve spee will provide posterior tooth contact during protrusion
  56. 56. LATERAL COMPENSATING CURVES a).Compensating curve for Monson curve “ The curve of occlusion in which each cusp and incisal edge touches to a segment of the sphere of 8” in diameter with its center at glabella”-GPT runs across the palatal & buccal cusps of maxillary molars.
  57. 57. B). WILSON’S CURVE “In the mandibular arch, that curve, as viewed in the frontal plane, which is concave above and contacts the buccal and lingual cusps of the mandibular molars; In the maxillary arch, that curve, as viewed in the frontal plane, which is convex below and contacts the lingual and buccal cusps of the maxillary molars. The facial and lingual cusp tips on both sides of the dental arch form the curve.” -GPT This curve is followed when first premolars are arranged. The premolars are arranged according to this curve so that they do not produce any interference to lateral movements.
  58. 58. C). PLEASURE CURVE/ REVERSE CURVE “A helicoid curve of occlusion that, when viewed in the frontal plane, conforms to curve that is convex from the superior view, except for the last molars which reverse that pattern.”-GPT Lateral view with 2nd PM & 1st molar follow the reverse curve Reverse curve is used in the bicuspid area for lever balance
  59. 59. 5). CUSPAL ANGULATION
  60. 60. Advantages of balanced occlusion : • Bilateral simulataneous contact help to seat the dentures in a stable position during mastication, swallowing and maintain retention and stability of the denture and the health of the oral tissues. • cross-arch balance. • Denture bases are stable even during bruxing activity. Disadvantages of balanced occlusion • It is difficult to achieve in mouths where an increased vertical incisor overlap is present – Class II cases. • It may tend to encourage lateral and protrusive grinding habits. • A semi adjustable or fully adjustable articulator is required.
  61. 61. NEUTROCENTRIC OCCLUSION Neutrocentric occlusion is at the far right of the occlusal spectrum and the exact opposite of the anatomic occlusion, was developed by De van. De Van coined the term neutrocentric to embody the two key objectives of his occlusal scheme, 1. The neutralization of inclines. 2. The centralization of forces which act on the basal seat when the mandible is in centric relation to the maxillae There are five elements in this occlusal scheme: • Position • Proportion • Pitch • Form • number
  62. 62. POSITION: • Positioned the posterior teeth over the posterior residual ridge as far lingually as the tongue would allow, so that forces would be perpendicular to the support areas. PROPORTION: • Reduction of tooth width upto 40%. • Reduced vertical stress on the ridge by narrowing the occlusal table. • Forces were centralized without encroachment on the tongue space. PITCH: • Pitch or inclination or tilt • There was no compensating curve and no incisal guidance. • This positioning directed forces perpendicular to the mean osseous foundation plane.
  63. 63. FORM: • Flat teeth with no deflecting inclines• Reduced destructive lateral forces and helped to keep masticatory forces perpendicular to the support. • Reduced destructive lateral forces and helped to keep masticatory forces perpendicular to the support. NUMBER: • The posterior teeth were reduced in number from eight to six. • This decreased the magnitude of the occlusal force and centralized it to the second premolar and first molar area.
  64. 64. ADVANTAGES : • Technique is simple and requires less precise records. • Ideal for a patient who have resorbed friable ridges. • By removing inclines, the lateral forces, which are very destructive to the residual ridges, are reduced. • Because the neutrocentric technique provides an area of closure and does not lock the mandible into a single position. Ideal for Geriatric patient with limited oral dexterity. • It is especially good for Class II (retrognathic), Class III (prognathic) and crossbite cases. DISADVANTAGES • It is the least esthetic of the five basic occlusal schemes. • Moving the teeth lingually and altering their vertical position may not be compatible with the tongue, lip and cheek function. • Impair mastication because of poor bolus penetration • This flat type of occlusion cannot be balanced When using this concept of occlusion the patient is instructed not to incise the bolus, with this tooth arrangement Devan noted that “the patient will become a chopper, not a chewer or a grinder”
  65. 65. LINGUALIZED OCCLUSION Concept was introduced by Alfred Gysi in 1927 S.H. Payne (1941): 'cusp-to-fossa occlusion' Pound: 'lingualized occlusion' “Lingualized occlusion can be defined as, the form of denture occlusion that where the maxillary lingual cusps articulate with the mandibular occlusal surfaces in centric working and non-working mandibular positions.”
  66. 66. Lingualized occlusion should not be confused with placement of the mandibular teeth lingual to the ridge crest Indications : • When patient places high priority on esthetics but oral conditions indicate a non-anatomic occlusal scheme such as:  Severe alveolar resorption  Class II jaw relationship  Displaceable supporting tissues. • When a complete denture opposes a removable partial denture. • When a more favorable stress distribution is desired in patients with parafunctional habits.
  67. 67. ADVANTAGES : • Lingualized occlusal concept is a simple technique requiring less precise records than fully balanced occlusion and is similar in requirements to nonanatomic teeth set on a curve. • Most of the advantages attributed to both anatomic & non-anatomic forms are retained. • Cusp form is more natural in appearance compared to non-anatomic tooth form. • Good penetration of food bolus is possible. This may reduce the lateral chewing component. • Vertical forces are centralized on mandibular teeth & it provides an area of closure, allowing easier accommodation to unpredictable basal seat changes. • With lingualized occlusion, additional stability is imparted to the denture during parafunctional movements when balanced occlusion is used • Can be used in Class II, Class III & cross-bite situations
  68. 68. DISADVANTAGES : Wear of maxillary lingual cusp or mandibular fossa rapidly results in buccal and lingual contact of equal intensity results in negotiation of centralization of forces on the mandibular posterior teeth and increase the like hood of lateral displacement.
  69. 69. MONOPLANE OCCLUSION Sear introduced monoplane occlusion with balancing ramps or tooth at the distal part of the mandibular arch which comes in contact only in eccentric excursions De Van has used the same principle without the balancing Ramp. According to this concept teeth which are flat mesiodistally and buccolingually are used, oriented as close as possible parallel to the maxillary and mandibular mean foundation plane.
  70. 70. MONOPLANE ARTICULATION:- Anterior teeth make contact in excursions (christensens phenomenon) Modifications have been made to minimize the tilting potential • Balancing ramps • Compensating curves
  71. 71. MONOPLANE OCCLUSION WITHOUT CONDYLAR INFLUENCE
  72. 72. INDICATION : • Abnormal closure imbalance, pathosis, trauma, neuromuscular disturbances. • Posterior displaceable mucosa. • Multilated, tortuous ridges with an excessive denture space . • Ridges are flat or knife edge, rendering dentures more suspectible to horizontal force. • When chewing pattern is milling type with broad excursions. • Maximum of vertical force and a minimum of horizontal stress is desired . • The amount of horizontal overlap is determined by jaw relation, ranges from 0mm (edge to edge) Class III relation to as much as 12mm for severe class II relation Usually the mandibular second molar will be placed on the molar slope area, called 'skid row'. In this the occlusal surface of the maxillary second molar set parallel to the occlusal surface of the mandibular second molar but 2 mm above the occlusal plane, well out of occlusion.
  73. 73. Monoplane occlusion can be balanced by following methods: • Incline the mandibular second molar to provide contact with the maxillary denture in all excursions, the maxillary second molars are similarly inclined but left out of centric contact. • The use of customized balancing ramp placed distal to the mandibular second molar. Ramp provides tripodal effect of contacts of denture bases.In eccentric relation, there is smooth contact anteriorly on teeth and posteriorly on the balancing ramp. Balancing ramp improves horizontal stability of the denture.
  74. 74. ADVANTAGES : • They are more adaptable to the unusual jaw relation such as class II and class III relations, used easily in cases of variations in the width of maxillary and mandibular jaws, cross bite. • These impart a sense of freedom to the patients, do not lock mandible in one position. • They eliminate horizontal forces, more damaging than vertical forces. • Because the monoplane teeth occlude in more than one relationship, so centric relation developed to an area instead of a point. • Monoplane teeth permit the use of a simplified and less time consuming technique and offer greater comfort and efficiency for a longer period. • They accommodate better to the negative changes in the ridge height that occur with aging
  75. 75. DISADVANTAGES : • No vertical component to aid in shearing during mastication. • Patients may complain of lack of positive intercuspation position. • Esthetically limited. • Occlude only in two dimensions, but the mandible has a 3D movement due to its condylar behavior
  76. 76. CONCLUSION Many occlusal schemes have been proposed over the years. Most schemes when correctly used gives satisfactory results. The result is satisfactory, if the patient gets better function, esthetics & comfort without any adverse changes in denture foundation.
  77. 77. REFERENCES

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