Denture Placement & Occlusion Correction Rola M. Shadid, BDS, MSc

Causes of Denture Errors Clinical errors Technical errors Inherent deficiencies in the material itself

Evaluation Procedures Processing Polished surfaces Tissue fit and comfort Retention, stability and support Jaw relations Occlusion Esthetics Speech

Evaluation of Processing * Inspect for processing errors, e.g. porosity Inspect for inadequate polishing Run your finger along the borders & impression surface to check if sharp edges or acrylic spicules exist Examine frenal notches for sharp edges Examine for adhered plaster or stone fragments It is imperative that clinician examine the denture thoroughly before inserting Corrections are made by scraping or grinding with knife, sandpaper, or stone burs

Patient Education & Preparation * First oral feeling with fullness is normal & will disappear over time Excessive salivation (compulsive spitting or rinsing should be avoided, instead swallowing encouraged to remove excess saliva) The pt should be aware that only after the dentist has completed evaluation and adjustment of denture in the mouth and is satisfied with it, will the pt be allowed to view it.

Evaluation of Tissue Fit & Comfort Pressure Indicating Paste (PIP)* Every new denture must be checked with PIP to identify and determine if pressure areas exist to reduce them. Commercial preparations are available. PIP can be prepared in clinic by mixing zinc oxide eugenol base paste with Vaseline. Light body elastomeric impression paste can also be used as PIP

Evaluation of Tissue Fit & Comfort Never adjust unless you can see exactly where to adjust Use indicator medium (PIP, indelible marker, etc)

Place Paste with Streaks

How to Read PIP? Streaks - no contact (N) No Paste - Impingement (I) Paste, no streaks - normal contact (C)

Evaluation of Tissue Fit & Comfort Severe undercuts Cause abrasion and soreness in seating and removal Management Relieve with extreme caution with aid of PIP

Evaluation of Tissue Fit & Comfort Overextended borders Denture appears to rise or has inadequate retention Management Identify the offending borders, mark with indelible marker inside the pt mouth and carefully reduce

Evaluation of Retention, Stability & Support Test for retention* Test for posterior palatal seal The finger is placed on the ridge and a rolling pressure is applied away from the side being checked. The denture should resist dislodgment. Posterior palatal seal is checked by applying pressure in anterior region

Test for Rocking Apply alternating finger pressure on occlusal surfaces of R & L sides Rocking around fulcrum point Midpalatal raphe is a common fulcrum point if inadequate relief has been provided * * The fulcrum point must be identified and relieved with the aid of PIP.

Evaluation of Occlusion Denture processing almost always causes changes in occlusion due to dimensional changes in resin These changes are usually manifested as increase in OVD

Causes of Occlusal Errors Errors in impressions Ill-fitting trial denture bases Inaccurate jaw relation records Errors during transfer of the records to articulator Incorrect arrangement of posterior teeth Dimensional changes during curing Processing faults……..* *Failure to close flask completely, too much pressure while closing the flask, tooth movement during flasking or packing, failure to cool flask before deflasking, distortion due to improper flasking, warpage due to overheating during polishing

Why is it difficult to detect occlusal errors in the mouth? * Negative attitude (assume an error exists and try to find it) *shifting of denture bases, incorrect closure by pt.

What is the ideal occlusal contact? At first contact, even maximum intercuspation at CR without denture shifting or instability & without pain * *sliding of denture bases or uneven pressure caused by faulty occlusion can lead to ulceration of mucosa.

Types of Occlusal Errors CO not coincide with CR Premature contact (high point) in one or both sides Uneven distribution of occlusal contacts Eccentric movement prematurities (protrusive & lateral)

What are the Methods of Detecting Occlusal Errors? Touch & slide method (Refer to lecture 9) Denture dislodges or shifts when pt occludes Pt complains of pain beneath denture bases *

Correction of Occlusal Errors Laboratory remounting Clinical remounting Direct intraoral correction

Laboratory Remounting * Disadvantages Cannot correct errors made while recording jaw relations Cannot correct errors made while mounting the casts on the articulator Does not compensate changes caused by settling of the denture bases Made in laboratory after processing and before the denture is inserted in mouth. The aim is to regain the original OVD that was disturbed by processing It is believed that adjusting the balanced occlusion is not necessary at this stage (immediately after processing and before insertion in mouth) because of settling of denture bases that occur after insertion. Settling changes the occlusal relationship; so it is wiser to wait for settling to occur before adjusting the balanced occlusion.

Clinical Remounting with New Interocclusal Records * Advantages Correct errors made during recording of jaw relations, or while mounting cast on articulator Less chair side time Corrections away from the patient’s view No saliva which makes detection by articulating paper difficult No shifting of dentures or incorrect closure by pt *the dentures are remounted on to an articulator from new interocclusal records made in patient’s mouth. Corrections are done by selective grinding on articulator.

The Aim of Clinical Remounting The prematurities are ground until multiple, uniformly distributed and even contacts are obtained bilaterally

Clinical remounting is currently the most commonly preferred method of occlusal correction

Clinical Remounting Procedure Ask patient to bite on cotton rolls for 10 min. Guide mandible into CR several times. Bite registration material is placed on the post. teeth of the mandibular denture

Clinical Remounting Procedure Guide mandible into CR Obtain interocclusal record of CR.

Clinical Remounting Procedure Mount upper denture using remounting jig Mount lower denture

Clinical Remounting Procedure

Selective Spot Grinding * *Articulating paper is used to identify the prematurities. Articulating paper should be placed bilaterally. The articulator is raised and closed with sharp repeated tapping motions. The prematurities are identified and reduced with a small conical stone bur or another suitable bur. The art of reducing premature contacting surfaces, so that an equal pressure exists at all points with interference at no point.

How to Recognize Premature Contacts? A dark ring with a light center usually denotes a premature contact You should distinguish betw. marks made by normal occlusal contacts and those of premature contacts Articulating paper should not be reused many times and should be changed often.

Selective Spot Grinding Make grinding until even (same intensity), stable, and multiple marks spread over wide area in both sides

Eliminating Occlusal Errors Re-establishment of CO. Correction of protrusive relation. Correction of working side occlusal errors. Correction of balancing side errors. Initially, centric occlusion errors are corrected, followed by protrusive, R & L lateral interferences.

Basic Tooth Positions Balancing Contacts Centric Occlusion Working Contacts

Selective Grinding Rules to Obtain CO After the first few taps on the articulating paper only a few high contacts appear. The marking process and the grinding are repeated until all except the anterior teeth contact in CO. Ideally all holding cusps * of the maxillary and mandibular posterior teeth will make simultaneous contacts. It is not uncommon for one or two functional cusps not to make contact after establishing the final CO. It is not necessary to continue adjusting until these cusps make contacts because aggressive adjustment will sacrifice the established OVD Holding, supporting or functional cusps are the maxillary palatal and mandibular buccal. The balancing non-functional cusps are upper buccal and lower lingual (BULL)

Selective Grinding Rules to Obtain CO As far as possible, avoid grinding cusp tips especially centric holding cusps, instead grind the opposing fossae or marginal ridges where the centric holding cusps occlude If the high contact is on the centric holding cusp inclines, the cuspal inclines can be reduced, thereby gradually moving the contact more toward the bearing cusp tip. A centric holding cusp may be reduced when it interferes with another centric holding cusp or when makes interferences in centric and eccentric positions

Re-establishment of CO Problem: Teeth too long Solution: Deepen the fossae

Re-establishment of CO Problem: Teeth too nearly end to end Solution: Grind Inclines

Re-establishment of CO Problem: Too much horizontal overlap Solution: Broaden central fossae

After the CO re-establishment…. DO NOT: Reduce maxillary lingual cusps. Reduce mandibular buccal cusps. Deepen the fossae.

Correction of Protrusive Relation The teeth are brought edge to edge Any interferences to smooth anterior gliding of dentures are eliminated by grinding Elimination of protrusive interferences along a path of 3 to 5 mm is sufficient

Correction of Working Side Occlusal Errors BULL rule buccal upper-lingual lower

Correction of Working Side Occlusal Errors Reduce lingual inclines of buccal cusps of upper teeth. Reduce buccal inclines of lingual cusps of lower teeth. ON WORKING SIDE ONLY!!!

Correction of Working Side Occlusal Errors Problem: Buccal and lingual cusps too long. Solution: Change inclines of balancing cusps.

Correction of Working Side Occlusal Errors Problem: Buccal cusps are too long Solution: Change lingual incline of maxillary buccal cusp

Correction of Working Side Occlusal Errors Problem: Lingual cusp too long. Solution: Change buccal incline of lingual cusp of mandibular tooth.

Correction of Balancing Side Errors On the balancing side, the cusps usually involved are the functional cusps and therefore grinding becomes more confusing

Correction of Balancing Side Errors Decide which supporting cusp maintains CO and reduce its opponent.

Correction of Balancing Side Errors Grind the lingual incline of the mandibular buccal cusp.

Direct Intraoral Correction Disadvantages Requires a lot of pt cooperation Pt should have good neuromuscular control Saliva Inaccurate closure by pt Misleading due to resiliency of tissues and shifting of denture bases

References Boucher's Prosthodontics Treatment for Edentulous Patients. Twelfth Edition.Chapter 20. Dalhousie continual education Complete Denture Prosthodontics, 1st Edition, 2006 by John Joy Manappallil, Chapter 19