Clinical and laboratory remoutning

Clinical and Laboratory Remounting with Selective grinding

1. Clinical and Laboratory Remounting in Complete Dentures Submitted by: Dr.Pallavi Chavan 2 nd year PG

2. Introduction Complete dentures are prosthetic replacements for lost natural teeth and lost soft and bony tissues, which are fabricated in order to restore impaired or lost functions and appearance Fabrication of complete dentures comprises various variables whose precise execution is of crucial importance for achieving success with fabricated dentures

3. The efficiency and comfort that a patient experiences using complete dentures depends to a large extent on the harmony of the occlusion Occlusion established during try-in stage is subject to change because of inaccuracies incorporated during construction of dentures

4. Minor faults can be corrected by selective grinding with dentures in patient's mouth, if a split cast remount procedure was used immediately after the dentures were processed. However, a general dental practice survey revealed that less than 5% of dentists use the split cast procedure to rectify the errors of processing

5. Prosthodontist’s recommend a remount procedure for identification and correction of occlusal errors in complete dentures rather than the more common practice of placing the articulating paper intra orally, followed by spot grinding at the chair side However, There is no evidence to support such recommendations

6. What is Remounting?? Definition: Remount procedure : Any method used to relate restorations to an articulator for analysis and/or to assist in development of a plan for occlusal equilibration or reshaping. Remount record index : A record of maxillary structures affixed to the mandibular member of an articulator useful in facilitating subsequent transfers

7. Causes of Errors in Occlusion : Incorrect Registration of Centric Occlusion: Reason A : During JR , when occlusal rims are brought together cause uneven pressure due to premature contact in the 2 nd molar or incisor region Compression of mucosa Displaces the mucosa away from the region of premature contacts

8. But , on plaster models there is no compression of tissues Thus , different relation in mouth and articulator Thus, an error is established which is passed through try-in and processing stages At denture insertion the dentures contact only in areas of these premature contacts Causes of errors in occlusion

9. Incorrect registration of centric occlusion Reason B: Imperfectly fitting record bases can cause movement of rims while recording centric The dentures will have slightly inaccurate centric occlusion relation and will tend to move on the ridges , causing soreness Reason C: The models may not be placed accurately on the articulator while mounting Causes of errors in occlusion :

10. Irregularities in Teeth Setting : Difficult to set perfectly even contact in teeth arrangement leading to some heavy contacts /pressure Wax has certain resiliency ,permits tooth movements to occur when interferences are encountered unlike hard acrylic in denture Wax can contract and move ,causing irregularities in teeth arrangement Causes of errors in occlusion :

11. Tooth movement while Flasking and Packing Tooth movement while de-waxing Excessive packing pressures results in, the artificial teeth being forced into the investing plaster If the acrylic resin has reached an advanced dough stage Normal packing pressures when the investing mix is weak can break the mould Causes of errors in occlusion :

12. Tooth movement while flasking and packing Incomplete Flask closure If pressure on the flask is released during the curing cycle Separation of the two halves of the flask by a layer of excess resin which should have been removed during trial closure of the flask(flash) Causes of errors in occlusion :

13. In spite of taking all due precautions to prevent the errors just described, small occlusal inaccuracies invariably occur. These errors can be corrected in the laboratory if a split-cast mounting technique is used . An average increase in height of 0.5 mm and a shift in tooth contact towards the posterior region T. Badel et al . Complete Denture Remounting ; Acta Stomatol Croat, Vol. 35, br. 3, 2001

14. Articulator wear: All articulators are subjected to wear and older and more worn the articulator the greater will be the error in occlusion and articulation Every piece of mechanical apparatus exhibits some play in its moving part and when this becomes easily detectable, the bearing should be replaced

15. Other factors Over heating during polishing procedures Inevitable dimensional changes in the denture material during and after polymerisation Expansion of the acrylic resin due to water absorption Shrinkage in denture makes the cuspal position Change in turn increasing VD.

16. Occlusal errors can be corrected by:

17. Direct Correction in Mouth 1.Articulating paper It will not give an accurate indication of premature contacts because of resiliency of supporting tissues that allows the denture to shift producing markings which are frequently false

18. 2. Central bearing plates: The correlator : It has a spring loaded central pin It contacts a metal plate in the vault This,hold the maxillary denture up and mandibular denture down At a premature contact,the dentures do not shift because the spring holds the teeth apart Coble device: Has a central bearing pin without spring Coble device

19. 3.Occlusal waxes: Adhesive wax is added on the mandibular denture Points of penetration are observed and relieved Advantage : Can locate interference in functional movements Disadvantage: Can give false reading due to shift of underlying soft tissues

20. 4.Abrasive pastes: Should only be used to refine occlusion after selective grinding on articulator Disadvantages: Shifting bases cause premature contacts Cusps maintaining vertical dimension might be destroyed

21. When to do Remounts ??

22. Laboratory Remounting: Purpose: To correct errors in processing To return dentures to the correct vertical dimension To restore centric and bilateral balanced occlusion

23. After processing, but before the removal of the dentures from their casts, they are returned to the articulator. This is accomplished by using split-cast mounting techniques, which allow easy location and removal of the cast from its mounting plaster on the articulator. Split Cast mounting technique:  1. procedure for placing indexed casts on an articulator to facilitate  their removal and replacement on the instrument; 2.  the procedure of checking the ability of an articulator to receive or be adjusted to a  maxillomandibular  relation  record.

24. Split-cast mounting is carried out in the laboratory, by notching the base of the cast and applying separating medium just before articulating the casts. The cast is easily separated from the mounting plaster and is flasked after the try-in. The cast can be removed from the flask and reattached to the mounting plaster using cyanoacrylate glue.

25. Split Mounting Plates Plexi glass with embedded split mounting plate part Split mounting plate has 3 metal plates and a pin Opposing section of split plate attached to the embedded section

26. Split Mounting Plates : Pin removed ; plexiglass detached and other section of split plate attached to cast Impression is boxed and poured and plexiglass is positioned on it

27. Masking tape wrapped around cast on the articulator The boxing is filled with plaster Tapered pin is removed and cast seperated

28. Procedure for Laboratory Remounting After Remounting ,check the incisal pin and incisal table contact (1-3mm) Check contacts between heals of the casts and dentures Place articulating paper ,and gently tap After the centric check eccentric and protrusive contacts Adjust these contacts by selective teeth grinding

29. Clinical Remounting It consists of remounting the finished denture on an articulator by using new inter- occlusal records in the patients mouth The purpose of clinical remounting is to accommodate the errors made during centric relation records

30. Advantages : It reduces patients participation It permits the dentist to see better what he /she is doing It provides stable base ,eliminating the resilient tissues Absence of saliva makes markings more accurate

31. Steps for Clinical Remounting Registration of centric relationship without tooth contact Lateral or protrusive records Facebow registration Mounting the dentures Correcting the occlusion by spot grinding

32. Registration of Centric Relationship without Tooth Contact

33. Remounting at Increased Vertical Dimension or Correct Vertical Dimension?? When the vertical discrepancy is 2 mm or less, we are often tempted to record the new interocclusal record at the same vertical But,when even one tooth makes contact on one side ,it can shift the bases and cause inaccurate records . Steps for clinical remounting

34. Therefore, The remounting records are made at higher vertical dimensions i.e :if 2 mm of error + 1-2 mm of material space = 3-4 mm of increased vertical dimension This increase should be nullified back,to the original vertical dimension by grinding Steps for clinical remounting

35. Occlusal errors at wax try-in stage can be corrected by removing the interfering tooth/teeth New interocclusal record is then made at the same vertical dimension This is a more accurate and physiologically appropriate method Steps for clinical remounting

36. Procedure for Interocclusal Record without Tooth Contact Two aluwax doubled layered strips (1/2”) are immersed in water bath of 54 c for 30 sec. Maxillary denture is seated in mouth, followed by mandibular and stabilized with the index finger over buccal flange area. Then the Mandible is guided into CR closing lightly into the wax. Steps for clinical remounting

37. As contact with the wax approaches the fingers are removed and the patient is instructed to close into the wax until a good index is made The imprints of opposing teeth must be crisp and 1mm deep with no penetration of wax record by opposing teeth If the teeth make contact ,the lower cusp will guide the mandible to the previous wrong position of occlusion ,thus preventing the desired correction Steps for clinical remounting

38. III. Facebow Registration : Sufficient amount of wax is adapted on the prongs of facebow fork The patient closes on the fork , facebow is then attached to the fork and related to the condylar heads Why facebow ??? A facebow is used to record the relationship of the upper denture to the patient's mandibular hinge axis and transfer this to an articulator, using the hinge axis of the articulator as a reference. If a facebow is used it allows the teeth to contact by rotating about an arc of closure identical to that of the patient. A facebow is therefore often used to remount the processed dentures on an articulator for the correction of occlusal errors Steps for clinical remounting

39. IV. Mounting Dentures in Adjustable Articulators Fabrication of clinical remount casts: Serve as an accurate, convenient and time saving method of reorienting the completed dentures on articulator for occlusal correction All undercuts on the tissue surface of the dentures are filled with wet tissue paper, pumice Steps for clinical remounting

40. Fast setting plaster or dental stone is poured into the denture Steps for clinical remounting

41. The maxillary remount cast is attached to the maxillary member of the articulator using the facebow transfer jig Steps for clinical remounting

42. Fabrication of the Facebow Transfer Jig Steps for clinical remounting

43. Mounting for Clinical Remount The remounting jig and the index are positioned on the mandibular member of the articulator, The maxillary denture and the remounting casts are placed in plaster indentation. The maxillary cast is attached to upper member of the articulator with plaster The lower denture is attached to the upper denture with help of wax interocclusal records Steps for clinical remounting

44. The condylar guidance can be set with the help of protrusive and lateral records After the plaster is set,the incisal guide pin is tightened and the record is removed ,there should be no contact of teeth The incisal pin is then removed and occlusion is set by selective grinding procedure Steps for clinical remounting

45. A simplified Chairside Remount Technique using Customized Mounting Platforms This clinical remount technique utilizes maxillary and mandibular CMPs (Customized Mounting Plates) that are fabricated over mounting plates of articulator.. Boxed mounting plates 6.5mm 2 mm 2.5mm Chauhan et al J Adv Prosthodont . 2012 Aug ; 4(3): 170–173.

46. Horseshoe shaped grooves U-shaped positive replica of edentulous ridges with Acrylic (5-6mm)

47. Customized mounting platforms secured on articulator Remount casts obtained in putty impression material. Mounting done with centric interocclusal record.

48. V.Selective Grinding Procedure In order to produce a satisfactory result, it is important to carry out grinding in a systematic way to : The VD maintenance Even distribution of occlusal stresses in CO. Even distribution of occlusal stresses maintained in lateral position. Steps for clinical remounting

49. Hammer and Anvil concept: As an aid in determining where on the teeth adjustments are to be made Supporting cusps considered as Hammer The portion of tooth contacted by them as Anvil The rule is, Adjust the anvil ,NEVER the hammer,thus preserving our centric stops The vertical dimension is controlled by these cusps ,therefore they should receive special consideration Bailey DCNA April 1995 39(2)

50. Grinding in Centric The first objective is to remove premature contacts in centric occlusion Mark the interfering cusps with articulating paper In the retruded contact position there are three types of occlusal errors and each can be corrected by specific grinding Any pair of antagonist teeth can be too long and thus hold other teeth out of contact’ The lower and upper teeth can be placed almost edge-to-edge The upper teeth can be positioned too buccally in relation to the lower teeth .

51. When cusps are too long : 1.If the offending cusp makes premature contact in centric as well as eccentric ground the cusp 2.If the offending cusp makes premature contact in centric only ,deepen the opposing fossa

52. The lower and upper teeth can be placed almost edge-to-edge Broadnening the central fossae : LINGUAL inclines of the UPPER BUCCAL cusps and BUCCAL inclines of the LOWER LINGUAL teeth are ground Narrowing the cusps: Reducing palatal inclines of upper palatal cusps Reducing buccal inclines of lower buccal

53. The upper teeth positioned too buccally in relation to the lower teeth The palatal cusp is ground in the palatal direction and the mandibular buccal cusp in the buccal direction so that teeth can enter each other.

54. Grinding in Eccentric Free sliding eccentric movements are important to Reduce stress on ridges Retention stability Rule for eccentric grinding is ….Always adjust that which is moving

55. On the Working Side there are six types of Occlusal Errors The maxillary buccal cusp and the mandibular lingual cusp are too long The buccal cusps are in contact, but the lingual are not The lingual cusps are in contact, whereas the buccal are not The maxillary buccal or palatal cusps are positioned more mesially from their intercuspal position The maxillary buccal or lingual cusps are positioned more distally from their intercuspal position The teeth on the working side can be out of contact

56. 1. The maxillary buccal cusp and the mandibular lingual cusp are too long The inner inclines of BUCCAL cusps of UPPER and LINGUAL cusps of LOWER (BULL) are adjusted 2. The buccal cusps are in contact, but the lingual are not The lingual inclines of upper buccal cusps are ground

57. 3. The lingual cusps are in contact, whereas the buccal are not Buccal inclines of mandibular lingual cusps are reduced 4.The maxillary buccal or palatal cusps are positioned more mesially from their intercuspal position (MU-DL ) Mesial inclines of the UPPER buccal cusps Distal inclines of the LOWER buccal cusps

58. 5.The maxillary buccal or lingual cusps are positioned more distally from their intercuspal position maxillary cusps distally and on the mandibular cusps mesially 6 . The teeth on the working side can be out of contact This is because of intense contact on the balancing side

59. Occlusal Errors on the Non-working side Mandibular buccal cusp are adjusted to reduce the incline of the part of the cusp that prevents tooth contacts on the working side

60. Occlusal Errors in Protrusion Accoroding to Boucher If the lateral eccentric contacts are corrected the protrusive grinding also have been accomplished However,premature contacts on the incisors are corrected at expense of Incisal edges of lower anteriors

61. Perfecting Articulation with Grinding Paste The main correction of occlusal irregularities must be carried out using a small mounted abrasive stone in a hand piece to maintain VDO A paste of coarse grit carborundum powder mixed with Vaseline/toothpaste is used followed by fine grit carborundum to produce the even occlusal contacts The sharp edges occurring buccally and lingualy must be rounded to prevent tongue and cheek irritation

62. Eliminating Occlusal Errors in Non-Anatomic Teeth Maxillary posterior are flattened by sanding on ultrafine sand paper against a truly flat surface After placing on the remount casts and articulation,occlusal contacts are marked Selective grinding is done only on the mandibular teeth

63. Occlusal Adjustment in Average Value Articulator Using a simple hinge articulator is not satisfactory, as lateral excursions are not possible The retruded contact position is recorded intraoral using soft wax The upper denture is articulated so that the center pin, touches the mid-line at the upper incisal edge.

64. The lower denture is attached to the articulator ensuring that the occlusal plane is horizontal and parallel to the base of the articulator When the plaster has set, the wax is removed between the occlusal surfaces of the teeth and the occlusal adjustment is carried out

65. Full Dentures Opposed to Partial Dentures When maxillary complete dentures and mandibular partial dentures: Lower impression with the partial denture in situ When casting the impression RPD must be retained in it Similar procedures as previously mentioned are carried out Avoid grinding natural teeth

66. Partial Upper an Lower Dentures For maxillary and mandibular distal extensions with only anterior teeth remaining previously described procedures can be carried out For small partial dentures,the opposing natural dentition is adjusted

67. Conclusion Correct occlusal relationships are a part of the success in prosthetic treatment for edentulous patients with complete dentures. A clinical remount procedure of the finished dentures is a constituent part of prosthetic patient treatment in practice of complete dentures. According to a study done by Kamal Shigli et al the results indicated that the laboratory and clinical remount procedures,along with occlusal corrections, reduced the number of areas of tissue irritation, postinsertion visits, pain during mastication and swallowing, and discomfort during mastication, and enhanced the comfort of the patient

68. The clinical remount also maintains the stability of dentures when the mandible is in centric relation position Selective grinding helps to remove the occlusal errors in a systematic way Occlusion of such dentures is more stable for longer time and with less parafunctional movements and Hence, a more Satisfied Patient

69. References : Syllabus of complete Dentures ; Heartwell 4 th edition Prosthodontic Treatment for Edentulous Patients ; Zarb , Hobkirk et al 13 th edition Dental Laboratory Procedures volume 1 ;Rudd and Morrow Fenn , Liddelow , and Gimsons ' clinical dental prosthetics Bailey et al Occlusal Adjustment ; DCNA april 1995 ;39(2)

70. Chauhan et al A simplified chairside remount technique using customized mounting platforms; J Adv Prosthodont . 2012 Aug ; 4(3): 170–173. Tomislav Badel et al Complete Denture Remounting Acta Stomatol Croat, Vol. 35, br. 3, 2001. Kamal Shigli The effect of remount procedures on patient comfort for complete denture treatment J Prosthet Dent 2008;99:66-72 Lang et al ;Complete Denture Occlusion ;DCNA 2004 48 :641—665