Teeth arranging for complete denture /continued dental education


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Teeth arranging for complete denture /continued dental education

  1. 1. Arranging Teeth For Complete Denture Occlusion INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  2. 2. Once the master casts have been mounted on the articulator, the teeth are set in the occlusion rims so a more accurate observation can be made of the jaw relationship recorded and eventually the occlusion established. www.indiandentalacademy.com
  3. 3. • The incisive papilla is a valuable guide to anterior tooth placement because it has a constant relationship to the natural central incisors. • It also serves to position the midline of the upper denture or, more specifically, the central incisors in the dental arch. • However, the centre of the face must also be kept into consideration when locating the midline for the teeth arrangement. www.indiandentalacademy.com
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  5. 5. • A line marking the centre of the incisive papilla can be extended onto the land area of the cast. • The central incisors are placed on either side of this line. www.indiandentalacademy.com
  6. 6. • The incisive papilla also aids in anteroposterior positioning of the teeth. • The labial surfaces of the central incisors are usually 8 to 10 mm in front of the papillae. www.indiandentalacademy.com
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  8. 8. • However, the distance for obvious reasons, will vary with the size of the teeth and the labiolingual thickness of the alveolar process carrying the teeth. • So it is not an absolute relationship. • Another guide to position the central incisors is their relationship to the reflection of soft tissues under the lip or as recorded in the maxillary impression. the labial surfaces and incisal edges of the teeth are anterior to the tissues at the reflection, where the denture borders will be placed. www.indiandentalacademy.com
  9. 9. • The root of the natural tooth extends into the alveolar process, with a relatively thin layer of bone over it labially. This means that in some situations the residual ridge can be used as a guide to determine the proper inclination of anterior teeth. • However, the accuracy of this guide decreases as resorption of the residual ridge progresses. www.indiandentalacademy.com
  10. 10. • The anteroposterior position of the dental arch should be governed chiefly by consideration of the orbicularis oris and its attaching muscles and by the tone of the skin of the lips. www.indiandentalacademy.com
  11. 11. The anterior teeth should be placed to support the lips to maintain the normal muscle tonus. Placing them too far posteriorly, allows the muscles to go unsupported and lips to sag. Placing them too far anteriorly stretches the muscles and results in a smaller looking mouth. www.indiandentalacademy.com
  12. 12. Notice the lack of tone in the skin of the upper lip Teeth positioned correctly in an anteroposterior direction. Notice the improved skin tone. www.indiandentalacademy.com
  13. 13. • A stretched appearance of the lips and philtrum indicates that teeth are positioned too far anteriorly www.indiandentalacademy.com
  14. 14. • Setting teeth over the maxillary anterior ridge may undermine the esthetic result. • The greatest harm is done when the maxillary anterior teeth are set too far back on the ridge or under the ridge. • In the resorbed situation, the crest of the ridge is considerably more posterior than it is in a patient with recent extractions, if the rule of setting teeth over the ridge is followed after the ridge has resorbed, a prematurely aged appearance will result. www.indiandentalacademy.com
  15. 15. The four principal factors that govern the positions of the teeth for complete dentures are (1) the horizontal relations to the residual ridges, (2) the vertical positions of the occlusal surfaces and incisal edges between the residual ridges, (3) the esthetic requirements, and (4) the inclinations for occlusion www.indiandentalacademy.com
  16. 16. HORIZONTAL POSITIONS The horizontal positions of teeth to the residual ridges involve placing the teeth anteroposteriorly and mediolaterally (1)to provide stability, (2) to direct the forces of mastication to areas most favorable for support, (3) to support the lips and cheeks for esthetics, and (4) to be compatible with the functions of the surrounding structures. www.indiandentalacademy.com
  17. 17. • Forces directed at right angles to the supporting tissues are more stabilizing than forces directed at an inclined plane. • The artificial teeth must be placed in suitable horizontal positions to allow the muscle activity to occur naturally www.indiandentalacademy.com
  18. 18. • The positions of the teeth influence the phonetics as exemplified by the J, ch, and sh sounds. •When the maxillary anterior teeth are placed too far posteriorly as related to the lower lip, the J sound may be muffled. •It may be necessary to arrange the mandibular anterior teeth with more labial version to aid in the correct enunciations of the ch and sh sounds www.indiandentalacademy.com
  19. 19. • In mastication, the tip of the tongue reaches into the buccal and labial vestibules, gathers the food, and places it on the occlusal surfaces. • When the teeth are placed too far in a lateral or anterior direction, the vestibular spaces are obstructed to the tongue. • When the teeth are placed too far in a medial or posterior direction, the tongue will dislodge the mandibular denture in an attempt to reach over the teeth www.indiandentalacademy.com
  20. 20. The crests of the residual ridges are aids in positioning the artificial teeth if the natural teeth were recently extracted and the cortical plates of bone remain intact. Unfortunately, the crests of the residual ridges do not remain in the same anteroposterior or mediolateral positions. www.indiandentalacademy.com
  21. 21. As resorption of alveolar ridge progresses, the maxillary arch becomes narrower and the mandibular arch becomes broader. www.indiandentalacademy.com
  22. 22. Guidelines for placing teeth in original centre of mandibular ridge • Retromolar fossae • Retromolar papilla • Retromolar pad • Mandibular canine region www.indiandentalacademy.com
  23. 23. LIMITS TO PLACING POSTERIOR TEETH • The mandibular arch determines the posterior limit for placing posterior teeth • Mucosa considered capable of bearing stress terminates at the retromolar papilla • Medial extension of the mylohyoid ridge determines the medial limit in placing mandibular posterior teeth- if placed more lingually than it, elevating the tongue may dislodge the denture • Actions of tongue and cheek, alongwith esthetics determine the lateral limits of mandibular posterior teeth www.indiandentalacademy.com
  24. 24. LIMITS TO PLACING ANTERIOR TEETH. •Involves placing the teeth in an anteroposterior and mediolateral position in harmony with the action of the lips and the tongue. •Establish horizontal overlap sufficient to prevent the anterior teeth from contacting when the posterior teeth are in centric occlusion . www.indiandentalacademy.com
  25. 25. POSITIONING OF THE TEETH ACCORDING TO THE HORIZONTAL RELATION OF THE JAWS . Maxillary arch is broader Using larger teeth buccolingually may than the mandibular arch be required. Maxillary arch is smaller The buccolingual relations of the teeth than the mandibular arch are reversed Place the buccal cusps of the mandibular teeth lateral to the buccal cusps of the maxillary teeth www.indiandentalacademy.com
  26. 26. The mediolateral and anteroposterior positions of the anterior teeth influence sounds in speech. f – incisal edges of maxillary centrals should barely contact the vermillion border of the lower lip. s- mandibular anterior teeth affect the s sound . th – the tip of the tongue should make contact with the palatal surface of maxillary anterior teeth www.indiandentalacademy.com
  27. 27. •The artificial maxillary central incisors should be placed anterior to the incisal papilla regardless of he relation of the papilla to the existing residual ridge •When natural teeth are present, the inclinations of the anterior teeth, as related to the crest of the alveolar ridge, are downward and forward. Usually this relationship is accentuated as resorption takes place. www.indiandentalacademy.com
  28. 28. • The upper lip is supported in the area of the philtrum by labial surfaces of the maxillary anterior teeth and at the corners of the mouth by the canines. • In normally related jaws, the border of the lower lip is supported by the labial incisal third of the maxillary anterior teeth. www.indiandentalacademy.com
  29. 29. Definite anatomic landmarks to be used as guides in arranging the anterior teeth are (1)the incisal papilla (2)the midsagittal suture, and (3)the canine lines. By locating these landmarks and recording their positions on the cast, one establishes points of reference indispensable to the correct arranging of the teeth www.indiandentalacademy.com
  30. 30. In the absence of other more definite information, the arch form is used as a guide for the initial arrangement of the teeth The anterior teeth for the tapered arch places the central incisors farther forward than the canines . The anterior teeth for the square arch places the central incisors nearly horizontal with the canines. The anterior teeth for the ovoid arch places the six anterior teeth in gentle curve. www.indiandentalacademy.com
  31. 31. A-SQUARE , B- TAPERING, C- OVOID www.indiandentalacademy.com
  32. 32. •The size and shape of the head are reliable factors in determining arch form. •Round heads are associated with square arches and a broad flat arrangement of the anterior teeth. The labial surfaces of the central incisors are in full view, and the canines are prominent. •Long narrow heads are associated with long narrow, palates, tapered arches, and a tapered anterior tooth arrangement. www.indiandentalacademy.com
  33. 33. VERTICAL POSITIONS The arrangement of artificial teeth in the correct vertical positions involves placing the anterior and posterior teeth in an acceptable position between the two residual ridges in a vertical direction. As in correct horizontal positioning, correct vertical positioning of the teeth should provide (1) denture stability, (2) favorable forces, (3) support for the lips and cheeks, and (4) compatibility. www.indiandentalacademy.com
  34. 34. •Natural teeth lose contact and migrate; they assume abnormal relations and positions when subjected to forces beyond the physiologic limits. Natural teeth extrude when their antagonists are removed, and at times the teeth and bone extrude as a unit. They can also be intruded. •To place the artificial teeth in the exact positions occupied by the natural teeth may not be tolerated during functions involving mandibular movements even though the teeth appear natural. •A compromise between appearance and function may have to be reached for a favourable prognosis. www.indiandentalacademy.com
  35. 35. •When the mandibular teeth extend too high, the tongue cannot reach the labial or buccal vestibules to retrieve the food. •When the mandibular teeth are too low, the tongue will not be supported at the lateral margins and will therefore enlarge in a lateral direction. •The tongue apparently accommodates more readily for anteroposterior changes in position than for vertical changes in position. www.indiandentalacademy.com
  36. 36. •The length and horizontal position of the central incisors should be such that when an individual says "five" or "valve" the teeth should come into slight end-to-end contact with the center of the lower lip. •The anteroposterior occlusal plane is established when the mandibular posterior teeth are placed at their correct vertical length and the maxillary anterior teeth are placed at their correct vertical length on a plane . www.indiandentalacademy.com
  37. 37. VERTICAL POSITIONS OF MANDIBULAR POSTERIOR TEETH. Two anatomic guides to establish the vertical position of the occlusal surfaces of the posterior teeth are (1) the orifice of the duct of the parotid gland (Stensen's duct) and (2) the retromolar pad. 1. The occlusal surface of the maxillary first molar is measured approximately ¼ inch below the orifice of the duct from the parotid gland (Stensen's duct). www.indiandentalacademy.com
  38. 38. 2. The occlusal surface of the last mandibular natural molars is on a plane approximately at the bottom of the upper third of the retromolar pad. This vertical position is usually compatible with the activities of the tongue and the cheeks. The occlusal groove, on the inner surface of the cheek, is located opposite the occlusal plane of the natural mandibular posterior teeth. When this groove is present, it is a reliable guide to the position occupied by the occlusal surfaces of the natural mandibular posterior teeth and can be used as a guide to positioning the posterior artificial teeth in a vertical direction . www.indiandentalacademy.com
  39. 39. VERTICAL POSITIONS OF MAXILLARY ANTERIOR TEETH. Esthetics and phonetics are used to establish the vertical position of the incisal edges of the maxillary anterior teeth. The following are aids to establishing the vertical positions of the artificial teeth by using occlusion rims: 1. Attach hard wax occlusion rims to accurate, stable record bases. 2. Properly contour the occlusion rims in an anteroposterior and mediolateral direction. www.indiandentalacademy.com
  40. 40. 3. Instruct the patient to say "fifty-five" and establish the vertical length of the occlusion rims in the anterior section of the maxillary arch. 4. Reduce the posterior occlusal surfaces until the surface is parallel to a line drawn from the ala of the nose to the tragus of the ear . 5. Make a face-bow transfer and a centric relation record and attach the casts to the articulator. 6. Record the top of the retromolar pad on the cast. 7. Alter the occlusion rims so the posterior vertical positions of the mandibular rim are on a plane at the same level as the top of the retromolar pads and the anterior vertical position is in contact with the maxillary occlusion rims.www.indiandentalacademy.com
  41. 41. • Remember that the use of the ala – tragus line is an expediency and is not a reliable indication for the occlusal surfaces of the teeth. • The plane is not used unless it coincides with the other guiding factors. • Establish the plane , using the retromolar pad for the posterior and the incisal edge or low lip line for the anterior points ofwww.indiandentalacademy.com
  42. 42. Arranging the maxillary teeth • After selecting the anterior molds for the maxillary and mandibular teeth, the arrangement is left to the discretion of the individual dentist to achieve the esthetic needs of the patient. • Remove the maxillary wax occlusal rim on one side from the midline around the arch for a distance of approximately 1 inch www.indiandentalacademy.com
  43. 43. • To set the maxillary anterior teeth with the appropriate labial orientation, it may be necessary to grind the acrylic resin to reduce the thickness of the record base. • This is a common occurrence in clinical practice, and should always be performed before grinding the neck of the tooth. • A longer tooth clinically will provide a better esthetic result. www.indiandentalacademy.com
  44. 44. Maxillary Central Incisor: •The long axis of the tooth is perpendicular to the horizontal (labiolingual inclination) •Its long axis slopes towards the vertical axis ( mesiodistal inclination) •Slopes labially about 15 degrees when viewed from the side. •Incisal edge is in contact with the occlusal plane. www.indiandentalacademy.com
  45. 45. Maxillary Lateral Incisor: • Long axis slopes rather more towards the midline • Inclined labially about 20 degrees when viewed from the side • The neck is slightly depressed • The incisal edge is about 1mm short of the occlusal plane. www.indiandentalacademy.com
  46. 46. Maxillary Canine : •Its long axis is parallel to the vertical axis when viewed from both the front and side or it may be slightly to the distal. •The bulbous cervical half of the tooth provides its prominence. •Its cusp is in contact with the horizontal plane. . •The neck of the tooth must be prominent www.indiandentalacademy.com
  47. 47. • Remaining maxillary teeth are arranged on the other side of the arch to complete the anterior set up. • To maintain the set teeth in position, the wax supporting the teeth must be heated and sealed both to the teeth and to the record base. www.indiandentalacademy.com
  48. 48. First premolar: • Long axis is parallel to the vertical axis when viewed from the front or the side. • Its palatal cusp is about 1mm short of, and its buccal cusp in contact with, the occlusal plane. www.indiandentalacademy.com
  49. 49. Second premolar: • Its long axis is parallel with the vertical axis when viewed from the front or the side. • Both buccal and palatal cusps are in contact with the occlusal plane. www.indiandentalacademy.com
  50. 50. First molar: • Long axis slopes buccally when viewed from the front, and distally when viewed from the side. • Only mesiopalatal cusp is in contact with the occlusal plane. www.indiandentalacademy.com
  51. 51. Second molar: • Long axis slopes buccally more steeply than the first molar when viewed from the front, and distally more steeply when viewed from the side. • All four cusps are clear of the occlusal plane, but the mesiopalatal cusp is nearest to it. www.indiandentalacademy.com
  52. 52. Arranging the Mandibular Teeth www.indiandentalacademy.com
  53. 53. Mandibular central incisor: • Long axis slopes slightly towards the vertical axis when viewed from the front. • Slopes labially when viewed from the side. • Incisal edge is about 2mm above occlusal plane www.indiandentalacademy.com
  54. 54. Mandibular lateral incisor: • Long axis inclines to vertical axis when viewed from the front • Slopes labially when viewed from side but not so steeply as the central incisor. • Incisal edge is about 2mm above occlusal plane www.indiandentalacademy.com
  55. 55. Mandibular canine: • Long axis leans very slightly towards the midline when viewed from the front. • Leans very slightly lingually when viewed from the side • Neck is slightly prominent and the tooth is tilted to the distal • Tip at same level as incisors. www.indiandentalacademy.com
  56. 56. First premolar: • Long axis is parallel to the vertical plane when viewed from the front and the side. • Its lingual cusp is below the horizontal plane • Its buccal cusp about 2mm above it as it contacts the mesial marginal ridge of the upper first premolar. www.indiandentalacademy.com
  57. 57. Second premolar: • Long axis is parallel to the vertical plane when viewed from both the front and the side. • Both cusps are about 2mm above the occlusal plane. • The buccal cusp contacts the fossa between the two upper premolars. www.indiandentalacademy.com
  58. 58. First molar: • Long axis leans lingually when viewed from the front and mesially when viewed from the side. • All cusps are at a higher level above the occlusal plane than those of the second premolar. • The buccal and distal cusps are higher than the mesial and lingual. • The mesiobuccal cusp occludes in the fossa between upper second premolar and first molar.www.indiandentalacademy.com
  59. 59. Second molar: • Lingual and mesial inclination of the long axis is more pronounced than in the case of the first molar. • All the cusps are at a higher level above the occlusal plane than those of the first molar, the distal and buccal cusps more so than the mesial and lingual. • The mesiobuccal cusp contacts the fossa between the two upper molars. www.indiandentalacademy.com
  60. 60. Arranging the Posterior Teeth . The anatomical guides most often used in developing the anterior plane of occlusion are the comers of the mouth. The posterior plane of occlusion is an extension of this anterior plane level with the junction between the middle and upper third of the retromolar pads bilaterally. The height of the occlusal plane is not simply a matter of dividing the maxillomandibular denture space equally. This space is governed by the relative amount of bone lost from the two ridges. More bone may have been lost from the maxilla than from the mandible and the occlusal plane should not be placed an equal distance between the two ridges. It also should not be at a level that would favor the weaker of the two ridges (basal seats). The most reliable guides are esthetics or anterior tooth placement and the retromolar pads www.indiandentalacademy.com
  61. 61. The solution to the problem is to position the teeth along a line extending from the tip of the canine to the middle of the retromolar pad this arbitary line should pass through the central fossa of the mandibular premolars and molars The basic principle for the buccolingual positioning of posterior teeth is that they should positioned over the residual ridge. The canine retromolar pad should provide guides for arrangement. www.indiandentalacademy.com
  62. 62. Compensating curves • From the foregoing descriptions of the orientation of the teeth it will be seen that they are arranged so that the posterior teeth, when considered as a whole unit, form two curves, an antero-posterior and a lateral curve. • Are the artificial curves introduced into dentures in order to facilitate the production of balanced articulation. • Are the artificial counterparts of curves of Spee and monsoon which are found in the natural dentition. www.indiandentalacademy.com
  63. 63. Anteroposterior curve • Follows an imaginary line touching the buccal cusps of all the lower teeth from the lower canine backwards, and approximates to the arc of a circle. • A continuation of this curve backwards in the natural dentition (curve of Spee), will nearly always pass through the head of the condyle. www.indiandentalacademy.com
  64. 64. • The arrangement of posterior teeth in this anteroposterior curved manner is best appreciated by the following references and description. • If the path followed by the condyles is horizontal, then the teeth could be set to conform to a horizontal plane.when the mandible moves forwards the teeth will remain in contact. www.indiandentalacademy.com
  65. 65. • If the path travelled by the condyles is at an angle from the horizontal plane (as it always is to some extent), then as soon as the mandible moves forwards the condyles commence to descend, and the posterior teeth will lose contact if they have been set to conform to a horizontal plane. www.indiandentalacademy.com
  66. 66. • If the posterior teeth, instead of being set on a horizontal plane, are set to an anteroposterior curve, then as the mandible moves forwards and the condyles travel downwards, all the teeth can remain in contact www.indiandentalacademy.com
  67. 67. The lateral curves: • In the natural dentition there are two lateral curves, one involving the molar teeth ( the curve of monsoon), and the other involving the teeth anterior to the second premolars • The posterior curve has its concavity facing upwards and increases in steepness from before backwards, the occlusal surfaces of the upper molars facing outwards and downwards. • The anterior curve is a reverse of the posterior curve. www.indiandentalacademy.com
  68. 68. www.indiandentalacademy.com
  69. 69. • When the mandible is moved laterally the rotating condyle on the working side (i.e. the side towards which the mandible is moved) remains in the glenoid fossa and moves very slightly outwards and backwards ( Bennet movement). • The orbiting condyle on the other side ( balancing or non- working side) travels downwards and forwards. • If the teeth are set on a horizontal plane, those on the non- working side will lose contact, due to the downward movement of the condyle on that side. www.indiandentalacademy.com
  70. 70. • If the teeth are set on a horizontal plane, those on the non-working side will lose contact, due to the downward movement of the condyle on that side. www.indiandentalacademy.com
  71. 71. • If however, the teeth are set to conform to a curve, then steepness of which relates to the steepness of the condylar path, then the teeth will remain in contact during the lateral and downward movements. www.indiandentalacademy.com
  72. 72. WAXING AND CARVING OF THE WAXED UP DENTURE www.indiandentalacademy.com
  73. 73. Armamentarium required 1. Wax spatula 2. Le Cron carver 3. Chip blower 4. Bowl of chilled water 5. Cotton www.indiandentalacademy.com
  74. 74. • The form of the polished surface of a denture influences its retentive quality. • In addition, it influences the esthetic values of the denture. • The upper part of the polished surface, known as the “anatomical portion” should be formed in such a way as to lose none of the original border width of the impression. www.indiandentalacademy.com
  75. 75. • Generally speaking, fullness on the buccal and labial surfaces is desirable; and the opposite is true on the palatal surface of the maxillary denture, to provide all possible space for the tongue. • The lingual flange of mandibular denture should have the least amount of bulk, except at the border. This thickness at border is under the narrowest portion of tongue and it greatly enhances the seal by contacting the mucolingual fold. www.indiandentalacademy.com
  76. 76. • An excess of base plate wax is added on the buccal surfaces of mandibular and maxillary trial dentures. • The bulk of this cut back to the outer border of the cast.www.indiandentalacademy.com
  77. 77. • The small end of a Le Cron carver is held at a 45 degree angle to the tooth surface to form the wax gingival margin. • The common tendency is to cut this line too straight from the interproximal to interproximal, not leaving enough wax. It is well to have a surplus of wax along the gingival line and then to retrim. www.indiandentalacademy.com
  78. 78. • Triangular markings can be placed as a guide to the length and position of the root. • Root of maxillary canine is longest, lateral incisor shortest and central incisor root is in between of the two. • Root of mandibular canine is longest, central incisor shortest, and lateral incisor root is in between the two. www.indiandentalacademy.com
  79. 79. • The wax is scraped out of these triangular areas, after which the root indications will become manifest. • The sharp and rough indications are now rounded with a Le Cron carver and the wax spatula. They should not be over-emphasized. www.indiandentalacademy.com
  80. 80. • The lingual surface of the mandibular denture may be made slightly concave without extending the concavity under the lingual surface of the teeth. • A projection of tooth beyond their polished surface acts as an undercut into which the patient’s tongue will slip, thereby causing the denture to be unseated. (correct adjustment shown in diagram) www.indiandentalacademy.com
  81. 81. • The palatal surface of the maxillary denture should be waxed to a uniform thickness of 2.5 mm (sufficient for adequate strength and yet thin) • Lingual festooning restores part of the lingual surface of the tooth. • Wax is added and carved on the lingual side of the artificial teeth to imitate the normal lingual contours of each tooth.www.indiandentalacademy.com
  82. 82. • Polishing of the set up – Pass the waxed up denture slowly over the flame or use a chip blower to smoothen the surface. – Dip the setup immediately in the bowl of chilled water or use a wet cotton to gently rub over the flamed surfaces www.indiandentalacademy.com
  83. 83. Try-in Of The Waxed Up Denture www.indiandentalacademy.com
  84. 84. Purposes of the try in: • There is a good deal more to be checked about the dentures at the try in stage, than just appearance. • Two main objectives should be to compare the general tooth and arch position with the way the teeth might have grown. • We are used to hearing the expression, “ set the teeth on the ridge”, but this expression should be changed to say “ set the teeth as nearly as possible to where they grew!” • Physiologically the mouth and all its functions have matured in a certain pattern of conditioned reflexes and proprioceptive guidances. The more we deviate from this pattern, more the adaptation required by the patient. www.indiandentalacademy.com
  85. 85. Since so many points require checking, it is sound practice to get into the habit of working to a definite plan during the trial stage, and the following order is suggested. 1. The lower denture by itself (a) Peripheral outline (i) Buccal and labial (ii) Lingual (iii) Posterior extension (iv) Underextension (b) Stability to occlusal stresses (c) Tongue space (d) Height of the occlusal plane www.indiandentalacademy.com
  86. 86. 2. The upper denture by itself. (a) Peripheral outline (i) Buccal and labial (ii) Posterior border (b) Stability to occlusal stresses (c) Retention. www.indiandentalacademy.com
  87. 87. 3. Both dentures together (a) Position of occlusion (i) Horizontal relationship (ii) Vertical dimension (occlusal face height) (b) Evenness of occlusal contact (c) Appearance (i) Centre line (ii) Anterior plane www.indiandentalacademy.com
  88. 88. (iii) Profile and lip form (iv) Amount of tooth visible (vii) Phonetics (vii) Freeway space (e) Approval of appearance by the patient. www.indiandentalacademy.com
  89. 89. • Before carrying out these checks, remove the dentures from the articulator and place them in a bowl of cold water. • It is important that the waxed dentures should be frequently placed in cold water as wax softens appreciably at mouth temperature and, if left in the mouth too long, the teeth may be displaced and the bases may distort. • The method of carrying out these checks is as follows. www.indiandentalacademy.com
  90. 90. Trying the lower denture by itself: •Place the denture in the mouth and seat it on the ridge. Peripheral outline •The entire periphery should be checked to ensure that it is not over-, or under-extended The buccal and labial periphery •Hold the denture in place with light pressure on the occlusal surfaces of the teeth and move the cheek on one side upwards and inwards, thus simulating the action it makes when chewing. . www.indiandentalacademy.com
  91. 91. • Now relax the pressure on the teeth and observe if the denture rises from the ridge. • If it does, trim the periphery where it is seen to be over- extended until little or no movement occurs. • Pay particular attention to the buccal frena and ensure that they have adequate clearance. • Repeat for the opposite side and for the lip. • Note the bulk and shape of the buccal aspect of the denture. It should take the form of a gentle convexity in the molar region but concave in the premolar region • Such a contour will aid the muscular control of the denture as the cheek will tend to fit against the surface and hold the denture down. www.indiandentalacademy.com
  92. 92. The lingual periphery • Hold the denture in place with light pressure and ask the patient to protrude his tongue sufficiently to moisten his lips • if the denture lifts at the back, it is over-extended in the region of the lingual pouch. • Next, ask the patient to put the tip of his tongue up to the back of his palate; • if the denture lifts in the front, it is over-extended anteriorly, probably in the region of the lingual frenum.www.indiandentalacademy.com
  93. 93. • Such over-extension must be relieved, but care should be taken to avoid over-trimming, which occurs very easily owing to the difficulty of seeing the functional depth of the lingual sulcus when the denture is in place • Final adjustments are more easily and more accurately made after the finished denture has been worn for a few days, when areas of slight inflammation will indicate the precise location of over-extension. www.indiandentalacademy.com
  94. 94. Posterior extension Ensure that the heels of the lower denture are extended as high up the ascending ramus of the mandible as is practicable; the purpose of this is to buttress, the denture against the backward pressure of the lower lip www.indiandentalacademy.com
  95. 95. Under-extension • Though of less common occurrence than over- extension, it is equally important that the periphery should not be under-extended since dentures must cover the greatest possible area if maximum retention and support are to be obtained. • If the denture is found to be under-extended in any part of the periphery as shown by the presence of a gap between it and the functional position of the surrounding mucosa, replace the denture on the cast and check whether the base has been carried to the full extent of the impression at this point. www.indiandentalacademy.com
  96. 96. • If it has, it implies an inaccuracy in the impression which must be retaken before proceeding further. An alternative is to proceed to the finish stage and then rebase the denture to rectify the peripheral error. Stability under occlusal load • This test is used to determine if occlusal stresses will be transmitted unfavourably. • Apply pressure with the ball of the finger in the premolar and molar regions of each side alternately; this pressure must be directed at right angles to the occlusal surface. If pressure on one side causes the denture to tilt and www.indiandentalacademy.com
  97. 97. • If pressure on one side causes the denture to tilt and rise from the ridge on the other side, it indicates that the teeth on the side on which pressure is applied are set too far outside the ridge. • It may also indicate lack of adaptation of the base on the side being loaded or under-extended flanges on the side which rises. www.indiandentalacademy.com
  98. 98. Tongue space • Natural teeth occupy a position in the mouth where the inward pressure of the cheeks and lips is equalled by the outward pressure of the tongue, and it is into this zone of neutral pressure that the artificial teeth must be placed. • The tongue, being more mobile than the cheeks, will cause greater instability of the lower denture if the teeth are set on the lingual side of the neutral zone than if they are set on the buccal side. • If the tongue is cramped by the denture, lateral pressure will be exerted, producing instability when the tongue moves. www.indiandentalacademy.com
  99. 99. You can test for lack of tongue space as follows: • Ask the patient to relax the tongue, making sure that the denture is seated on the ridge, and then request him to raise the tongue. • If the tongue is cramped, the denture will begin to rise immediately the tongue moves. • This immediate reaction of the denture tends to differentiate the movement caused by a cramped tongue from the movement caused by lingual flange over- extension; movement due to the latter cause does not occur until the tongue has risen some distance.www.indiandentalacademy.com
  100. 100. The causes of lack of tongue space are: 1. Posterior teeth set inside the ridge. 2. Molar teeth which are too broad buccolingually. Such teeth should be replaced by smaller ones or their width reduced by grinding the lingual aspect (if the teeth are porcelain take care not to damage the retentive diatoric hole; if they are acrylic they should be polished before being finally set). www.indiandentalacademy.com
  101. 101. 3. Molar teeth leaning inwards. This will not always cause cramping of the tongue, but should never be allowed to occur as it interferes with the free vertical movements of the tongue. 4. Setting the upper teeth over the ridge almost invariably leads to the occluding lower teeth lying too far lingually. www.indiandentalacademy.com
  102. 102. Height of the occlusal plane • To obtain maximum stability of a lower denture, the occlusal plane of the lower teeth should be very slightly below the bulk of the tongue, so that the tongue performs the majority of its movements above the denture and thus tends to keep the denture down . • The denture must therefore be examined to see if the tongue, when relaxed, lies above or below the occlusal plane. www.indiandentalacademy.com
  103. 103. • Ask the patient to relax and place the tip of the tongue comfortably and without strain behind the lower front teeth, which is the normal relaxed position of the tongue, and then open his mouth without moving his tongue. If the height of the occlusal plane is correct, the tongue will be seen to lie on top of the lingual cusps. • If the lower denture still tends to rise unduly after the lingual periphery has been checked, and as much lateral space as possible for the tongue has been allowed, it may be necessary to reset the teeth completely, lowering the occlusal plane. This may be especially necessary in those patients who have a low tongue position www.indiandentalacademy.com
  104. 104. • The height of the occlusal plane is also of importance for the following reason: the greater the height of the lower denture, the longer will be the lower front teeth and the greater the surface exposed to the unfavourable pressure of the lower lip. This concludes the examination of the lower denture alone, and it should be removed from the mouth and placed in a bowl of cold water. • This concludes the examination of the lower denture alone, and it should be removed from the mouth and placed in a bowl of cold water. www.indiandentalacademy.com
  105. 105. Trying the upper denture by itself Place the upper denture in the mouth and examine in the following manner. Peripheral outline 1.The buccal and labial periphery is checked as for the lower denture. 2. The position of the posterior border is verified to check that the posterior edge is situated on the soft palate and that the postdam area on the cast has been placed correctlywww.indiandentalacademy.com
  106. 106. Stability Stability under occlusal load may be carried out as for the lower denture, but is intended to check the closeness of adaptation of the base against the mucosa and the future support of the denture in those cases where the mucosa is unevenly displaceable. www.indiandentalacademy.com
  107. 107. Retention Retention is checked by seating the denture with a finger on the vault of the palate and then attempting to remove the denture at right angles to the occlusal plane. Load is then applied upwards and outwards in one canine region to check the retentive force in the contralateral corner of the denture, i.e. in the region of the tuberosity vestibular space and pterygomaxillary notch. Then check the other side in the same way. www.indiandentalacademy.com
  108. 108. Both dentures together Remove the upper denture from the mouth, replace on its cast to confirm the fit, and chill in cold water for a few seconds. Then place both dentures in the mouth. If it is found necessary to improve the retention of the dentures when using a shellac type of base-plate, adhesive powder may be sprinkled on their fitting surfaces. www.indiandentalacademy.com
  109. 109. Position of occlusion Horizontal relation • Hold the lower denture in position on the ridge and ask the patient to relax, then to 'close on your back teeth' gently and maintain them in occlusion while the examination is carried out. • If the registration is accurate, the teeth will interdigitate in the mouth in exactly the same manner as they do on the articulator, but if the registration is wrong, the teeth will not interdigitate correctly and may even occlude cusp to cusp on one or both sides. www.indiandentalacademy.com
  110. 110. • The clinician must make quite certain that the occlusion he sees in the mouth is not due to movement of the dentures on the ridges, tilting of either denture or dropping of the upper denture. • This is best tested by asking the patient to keep the teeth together and then trying to separate the posterior teeth by means of a thin spatula or Le Cron blade. • This test should be carried out on each side of the mouth alternately. The teeth should be brought into occlusion several times, using any of the registration aids, in order to make certain that the position of occlusion is correct or, ifit is incorrect, to ascertain the type of error. www.indiandentalacademy.com
  111. 111. • i.e. whether the mandible can be retruded from the previously recorded jaw relationship, whether a lateral deviation has occurred, or whether there is a premature contact on one side before the other. • Observation of the upper and lower centre lines in relation to each other, with the dentures on the articulator and then in the mouth, will indicate a lateral deviation, if present. www.indiandentalacademy.com
  112. 112. • When the lower centre line is seen to be to one side of the upper centre line, with the dentures in the mouth, in contrast to the coincidence of these lines when viewed on the articulator, it is possible that the original registration was incorrect and that a lateral position has been recorded; this may be checked by the occlusion of the posterior teeth. • If the original position was incorrect, the lower cusps will be slightly farther back on one side indicating a greater retrusion of the condyle on that side. Should the lower cusps be slightly forward on one side, it indicates that the original recording of the occlusion was correct and the patient is now giving a lateral positionwww.indiandentalacademy.com
  113. 113. Major errors in the position of occlusion are easily detected, but minor errors may pass un-noticed; therefore it is extremely important to watch for any slight movement of the dentures on their respective ridges from the time the teeth first make contact until they reach the position of complete interdigitation www.indiandentalacademy.com
  114. 114. • the reason being that the cusp inclines of the teeth guide the dentures into occlusion and will move the dentures in relation to the ridges when only a slight error of jaw relationship exists from that which was obtained when taking the records. Care is needed when holding the lower denture in place on the ridge to avoid pushing it backwards. • When errors of occlusion are noted at this trial stage they must be corrected by re-recording the position of occlusion as follows www.indiandentalacademy.com
  115. 115. • The dentures are seated on the casts on the articulator and the posterior teeth removed from one of the dentures and replaced by wax which should be trimmed to occlude with the posterior teeth of the other denture without altering the vertical dimension as set on the articulator. • In this way considerable time may be saved in trimming the blocks in the mouth, as then only minor adjustments are necessary to produce even-ness of occlusal contact. www.indiandentalacademy.com
  116. 116. • The position of occlusion is recorded by adding a little softened base-plate wax to the chilled blocks, placing the dentures in the mouth and asking the patient 'to close on the back teeth, thus impressing the cusps of the opposing teeth into the wax without effecting any alteration in the vertical height. • Care must be taken to see that the new position of occlusion gives the necessary correction. Points which may help in this are observations of overlap, overjet, and the relation of the centre lines. www.indiandentalacademy.com
  117. 117. • When correcting a lateral deviation care must be taken to see that the lower anterior teeth do not impinge on the upper teeth, as this may cause the mandible to be guided into another incorrect position, or the dentures to tilt. • If any contact of the anterior teeth occurs the offending lower teeth should be removed and the position retaken. www.indiandentalacademy.com
  118. 118. • The advantage of removing posterior teeth from the upper trial denture is that in the re-recording the softened wax on the occlusal surface of the blocks is not interfered with by the operator's index fingers which are being used to control the lower denture. • The disadvantage is that the orientation of the occlusal plane, as determined by the upper posterior teeth, is temporarily lost. www.indiandentalacademy.com
  119. 119. • Removal of lower posterior teeth, on the other hand, means that the softened wax replacing the teeth is almost bound to be displaced or disturbed by the controlling index fingers. • It is better, therefore, to remove the upper teeth rather than the lower when rectifying an occlusal error www.indiandentalacademy.com
  120. 120. Check the vertical height • Ask the patient to relax with the lips closed. Watch the point of the chin and then ask the patient to close the teeth together; the chin should move upwards a small but definite amount. • If it is impossible to obtain this movement in spite of repeated attempts, it can be assumed that the vertical height is too great and, if this is excessive, there will also be a strained appearance when the lips are brought into contact with each other. www.indiandentalacademy.com
  121. 121. • It should be remembered that patients who are mouth breathers relax with their lips parted, and frequently have a large freeway space. • An over-closed vertical height will be associated with a large freeway space, and when the teeth are in occlusion the lips will be seen to be pressed too firmly together with some loss of the vermilion border. • In order to correct the vertical height the posterior teeth are removed from one of the dentures and replaced by wax blocks. www.indiandentalacademy.com
  122. 122. • The articulator should be closed or opened approximately the amount assessed to establish a suitable freeway space, and the blocks then trimmed to occlude with the opposing teeth at the new vertical height. • Final adjustments for evenness of occlusal contact, and for the production of the correct freeway space, are carried out in the mouth. • Once these are satisfactory, the record blocks should be chilled in cold water, and a little registration paste added to their occlusal surfaces to record the impressions of the opposing teeth when registering the retruded contact position. www.indiandentalacademy.com
  123. 123. Evenness of occlusal contact • Provided the horizontal and vertical relationships are correct, the evenness of the occlusion is next checked • As the teeth close, they should occlude evenly and with equally distributed pressure all round. • It frequently occurs that the teeth on one side of the mouth occlude slightly before those on the other, or the molars before the premolars. www.indiandentalacademy.com
  124. 124. This may be due to: 1. Pressure on the blocks being heavier on one side than the other when the records were taken. 2. A slight error when sealing the casts and blocks together or when mounting them on the articulator. 3. Warpage of the base-plates. www.indiandentalacademy.com
  125. 125. • To test for evenness of occlusal pressure, place two pieces of thin mylar tape between the teeth in the molar region, one on each side. • Request the patient to close and then endeavour to remove the tapes simultaneously, holding one with each hand, by pulling them out between the closed teeth. • Any difference in the force required to remove the strips will be readily appreciated, and if this force is interpreted in terms of occlusal pressure, an assessment may be made of whether or not it is even. • Repeat the test in the premolar regions. www.indiandentalacademy.com
  126. 126. Remember at all times to hold the dentures in place with the index fingers until final contact www.indiandentalacademy.com
  127. 127. Appearance • This aspect of the trial stage is a matter more for individual judgement, and sometimes the patient's ideas, than for set rules. However, certain factors need to be checked as routine Centre line. Stand in front of the patient, some distance away. A wrong centre line will be obvious. Minor errors may be corrected by adjusting the maxillary anterior teeth at the chairside but if the error is more than 1 mm the whole case may have to be reset www.indiandentalacademy.com
  128. 128. Anterior plane • This may be observed from the same position and any tendency for this plane to slope markedly up or down should be noted and corrected www.indiandentalacademy.com
  129. 129. • It is important to ask the patient to smile and if one side of the face rises more than the other it is good practice to set the anterior plane to run slightly up towards the elevated side. • This has the effect of making the smile less crooked and harmonizes the lip-tooth relationship. • Thought should also be given to the smile curve, i.e. the incisal edges of the maxillary incisors lying parallel to the smiling lower lip, as in most faces this produces a pleasing appearance. www.indiandentalacademy.com
  130. 130. Profile and lip form • Observe the patient's profile and note if the lips are either excessively distended or unduly sunken • In the first case, remove some wax from the labial flange and try the dentures again. • If this produces insufficient improvement, examine the denture to see if the teeth should be set farther in, or if smaller teeth can be used. • If the lips are sunken and inverted consider the need to set the anterior teeth further forward. www.indiandentalacademy.com
  131. 131. Amount of tooth visible. • Note how much tooth shows. • In this connection remember that a smiling person usually only shows the upper teeth. • If much of the lower incisors are visible, or only these teeth show, examine the amount of overlap and, if excessive, reduce it by altering the lower teeth. • If this does not effect an improvement, the position of the occlusal plane may require to be altered • Usually 1 to 2 mm of upper teeth should be visible at phonation. www.indiandentalacademy.com
  132. 132. phonetics • tooth positions are sometimes critical for sound production • An analysis of these sounds may be an indirect guide to correct placement of teeth. • Clinical experience suggests that s and t can cause most problems in a prosthodontic context. • The s sound and its relationship to the vertical dimension has been advocated to be used in denture construction, both for correct tooth positioning and for correct physiological VDO determination. www.indiandentalacademy.com
  133. 133. • If the there is too little space, the VDO is too large and speech distortions will occur. • Sounds such as s, sh , and th may be affected negatively. • During the pronunciation of the s sound, the interincisal seperation should average 1 to 1.5 mm. • Vertical length of anterior teeth during production of s www.indiandentalacademy.com
  134. 134. • Horizontal relation of anterior teeth during production of s www.indiandentalacademy.com
  135. 135. • Other sounds like f and v are also used as guides. • Are made between the upper incisors and the labiolingual centre to the posterior third of lower lip. • If the upper anterior teeth are too short ( set too high up),the v sound will be more like an f • If they are too long( set too far down), the f Will sound more like a v www.indiandentalacademy.com
  136. 136. Freeway space The teeth do not contact in the premolar region when the patient enunciates the sound m and s Usually 2 to 4 mm of space should be present in the premolar region. This also provides an indirect view of the correct positioning of the teeth. www.indiandentalacademy.com
  137. 137. Approval of appearance by the patient • It is always wise for the dentist to obtain the patient's approval of the appearance of the trial dentures before they are returned to the laboratory for finishing, as this allows for any mild adjustments. • Some patients are quite prepared to leave the question of appearance to the dentist,while others are extremely fussy over the smallest detail. • When dealing with the former, the dentist should still insist that they consider the matter of their appearance, otherwise when the dentures are finished the patient may react unfavourably. www.indiandentalacademy.com
  138. 138. • In the case of the fussy patient, much time and trouble must be spent on getting the shade, shape and setting of the teeth just as the patient wishes, but it is very important to obtain final approval before finishing the dentures. • In this connection the dentist often needs to use his restraining influence to avoid extremely bad errors of aesthetics and much waste of time. www.indiandentalacademy.com
  139. 139. Anterior try in • Sometimes only the anterior teeth may be arranged and the patient called for an anterior try in. • This helps in knowing the exact relationship of the teeth to the surrounding musculature, phonetics and also esthetics. • Patients views may also be obtained regarding the esthetical value and accordingly adjustments may be made. • Phonetics is also used as a guide to know the correct placement of teeth at the anterior try in stage. • Later the patient is recalled for a posterior try in when the posteriors have been arranged in accordance with the anterior try in done earlier.www.indiandentalacademy.com
  140. 140. • It should be remembered that other people will see more of a patient's dentures than the patient will, and if the dentures are not aesthetically pleasing in the opinion of his relations and friends he will usually become dissatisfied. • It is, therefore, advisable to ask the patient to bring a relation or candid friend with him at the trial denture stage and the approval or criticism of this second individual should be sought as well as that of the patient himself. www.indiandentalacademy.com
  141. 141. Thank you For more details please visit www.indiandentalacademy.com www.indiandentalacademy.com