Insertion of Complete Denture PDF

Insertion of complete denture Objectives of insertion stage of complete dentures: The overall objective of the insertion stage when fitting complete dentures is to ensure that the patient is given the best possible start with the new prostheses. This may be achieved by checking that: 1. There is n...

Insertion of complete denture Objectives of insertion stage of complete dentures: The overall objective of the insertion stage when fitting complete dentures is to ensure that the patient is given the best possible start with the new prostheses. This may be achieved by checking that: 1. There is no pain when the dentures are inserted and removed from the mouth, or when the teeth are brought into occlusal contact. 2. The teeth meet evenly. 3. The dentures stay in place when inserted and during normal opening of the mouth. 4. The patient understands: How to control the dentures. What to expect of them. How to clean them. The patient should have been instructed to keep any previous dentures out of the mouth for 12-24 hours immediately before the insertion appointment. This is essential because the new dentures should be seated on healthy and undistorted tissue, this is also important before taking the final impression. In general, the denture borders and flanges should be carefully examined by the dentist to ensure appropriate thickness, smooth rounded borders with no obvious overextension. If the impressions were accurately moulded, the denture should require no major alterations unless the laboratory operations have disregarded the effort made by the clinician. Checking surfaces of finished complete dentures before the insertion: All denture surfaces (polished, impression, occlusal) should be critically examined for small projections caused by invisible discrepancies in the cast or in the investing materials. A- Checking the polished surface and peripheries of the denture ▪ The polished surface of the denture should be well polished, smooth and highly lustered. ▪ The polished surface should be free from porosity because porosity decreases denture strength and allow the denture to break easily. Porosity will act as area of food and bacterial stagnation. ▪ All denture borders should be rounded and polished. B- Checking the impression surface Before inserting the new dentures for the first time, the impression surface must be carefully checked for any potential causes of pain. If found, these must be eliminated to ensure patient comfort and to avoid the adoption of abnormal paths of closure of the mandible. The tissue surface of the denture should be inspected by passing the little finger on the tissue surface of the denture and detect any rough or sharp edges. Air bubbles in the cast may lead to sharp projections on the tissue surface of the finished denture after processing. The common causes of pain arising from denture impression surface are: 1. An undercut flange: which traumatizes the mucosa when the denture is inserted and removed. The part of the flange causing discomfort is identified by direct observation and by using of a disclosing material such as soft wax. A thin, even layer of the disclosing material is applied to the suspect area and the denture is inserted and removed. The precise location of undercut producing the pain is shown up as an area of acrylic from which the wax has been displaced. 2. Acrylic spicules: These are produced by acrylic resin being processed into indentations found on the cast which are the reproductions of surface irregularities in the mucosa. These spicules, together with the acrylic nodules mentioned below, can be detected by observation of the dried impression denture surface and by passing a gauze napkin or cotton wool roll over the surface so that the cotton threads catch on the areas of spicules. 3. Acrylic nodules: Nodules occur commonly and are the result of acrylic resin being processed into small air blows in the cast. 4. Sharp acrylic margins: Sharp edges are associated with the presence of a tin-foil relief* on the cast. The relief area if present, should be rounded, and the edges should be beveled especially in the area of the mid palatine suture or torus palatinus. C- Checking the occlusal surface: once completion of the adjustments mentioned above, you must ensure that: Each denture can be inserted and removed from the mouth without discomfort. Firm pressure can be applied to the occlusal surface without causing pain. Checking the finished complete dentures after doing the initial placement: 1. Evaluation of the tissue surface of the denture from comfort and stability point of view. 2. Evaluation of the border extension which should completely full the vestibule within the anatomical limits. The posterior palatal seal area should be checked as well. 3. Checking of retention which is the quality of the denture that resists dislodgement in a vertical direction. This quality is checked by putting our finger on the central incisors of the denture and try to dislodge the denture upward and downward. 4. Checking the stability which is the resistance to denture movement against horizontal forces. It is checked by pressing on the premolars area, if there is any rocking when pressing on one side more than the other this is an indication for the lack of stability. 5. Checking the esthetic and facial contour. As the complete denture support the overlying muscles and facial tissues of an edentulous patient, it should restore not distort the muscle support of the face (lips and cheeks). The natural appearance of the complete denture is obtained by: 1- Proper positioning of teeth. 2- Proper contouring of denture flanges. 3- Correct height, thickness and shape of the flanges. 6. The centric occlusion of the artificial teeth should be coincided with the centric jaw relation. 7. Checking the vertical dimension (V.D): ▪ V.D is checked by measuring the distance between two points, one above the mouth and the other on the chin at physiological rest position and reducing 2-4mm will be the correct measurement of V.D at centric occlusion. ▪ Asking the patient to speak and count from 1-10 is also helpful in checking the V.D as phonetic is greatly affected by the space between the teeth so all the letters should be pronounced correctly. ▪ The facial appearance of the patient is good indication of inaccurate (increased or decreased) V.D. ▪ An increase or a decrease of the V.D should be corrected. if an increase of 2mm, selective grinding may solve the problem while with reduction in V.D, one of the dentures should be repeated. Sources of errors in finished complete denture: 1-Technical errors (clinical errors in judgment made by the dentist) e.g. centric off.. 2-Technical errors developed in the laboratory, e.g. broken cast. 3-Inherent deficiencies of the material used in the construction of the denture, e.g. expired acrylic. Clinical occlusal errors Errors in registering maxillomandibular relation may be the result of one or more factors: a) Record bases that do not fit accurately. b) A shifting of the record bases over displaceable tissues. c) Excessive pressure exerted by the patient during the registering of maxillomandibular relations. d) Unequal distribution of stress during the registering of maxillomandibular relations. e) Record bases placed on soft tissues that have been deformed by ill-fitting dentures. f) Patients not registering centric relation because of systemic factors such as muscle spasm, abnormalities of the temporomandibular joints and impairment of muscle tonus. g) Difference in compressibility between the soft tissue and that of the stone cast. This is true specially when the record bases are not correctly and accurately fit on the ridges. This error may appear as a premature contact in the finished denture. Laboratory occlusal errors Causes of errors Poor laboratory technique can result in the movement of individual teeth or in an increase in occlusal vertical dimension of the denture. As examples of the poor lab techniques are mentioned below and shown in figure 5: (1) Excessive packing pressures resulting in the artificial teeth being forced into the investing plaster. This can occur if the acrylic resin has reached an advanced dough stage and thus offers increased resistance to closure of the flask. Excessive pressure will then be needed to bring the two halves of the flask together. (2) When normal packing pressure breaks the investing plaster and causes movement of the teeth. This happened when the layer of investing plaster is weakened as a result of the use of an incorrect powder/water ratio or porosity in the mix. (3) If pressure on the flask is released during the curing cycle, the two halves are likely to separate, thus increasing the occlusal vertical dimension of the completed denture. (4) Separation of the two halves of the flask by a layer of excess resin, this results in an increased occlusal vertical dimension of the denture. Methods to check premature contact: During insertion of the dentures, it is important to start first with the lower denture because it is smaller and causes less gagging reflex. Thus, it is psychologically more acceptable by the patient. We have first to check the retention, stability and the peripheries of each denture. if there is any discomfort or pain, it should be relieved before checking the occlusion, otherwise the patient will never give a proper centric occlusion. Secondly, we must check the upper and lower dentures together inside the mouth. Checking premature contact is done by a method called selective grinding, which is defined as modification of occlusal surfaces of the teeth by grinding at selected places. This procedure is done to correct minor errors and to establish proper smooth occlusion during centric and eccentric relations. The portions of the teeth maintaining centric occlusion will not be destroyed. Types of the selective grinding: A- Intraoral selective grinding: this is done by using 1- The articulating paper: it is an acceptable method, but has many disadvantage: ▪ Cusps who are not in premature contact may be colored also. ▪ It doesn't record the fossa. ▪ Difficult manipulation, as we must put the articulating paper simultaneously on both sides, otherwise it leads to inaccurate record. 2- Occlusal indicator wax: horse –shoe shaped wax placed on the occlusal surface of the teeth, so any premature contact result in perforation of the wax. Disadvantages of intraoral selective grinding: 1- Because of presence of compressible tissue, we may have incorrect recording. 2- Presence of Saliva may distort the color of the articulating paper. 3- Difficult procedure in case of severely resorbed ridges (very old patient). 4- Cannot be used in case of gross changes in occlusion more than 3 mm space. 5- Psychological point of view, since the patient get better if the denture is given to him without any correction. B- Extraoral selective grinding: Some dentists prefer to do corrections of occlusal errors in the clinic at the time of denture insertion. This is also correct, but it might take time and some patients may think that these errors could be due to work, therefore it is advisable to do the corrections in the laboratory on the articulator, and if further adjustments are required, dentist can do it in the clinic. It is done just after the deflasking of the dentures and before the polishing. This is when we use a semiadjustable or 3 plane-articulator, so we remount the casts with the dentures and detect any processing changes in occlusion by using of articulating paper. We should check the centric occlusion, working and balancing occlusion and protrusive movement. Rules of selective grinding: 1- vertical dimension is maintained by occlusion of the functional cusps which are upper palatal cusps and lower buccal cusps so never grind from them. 2- if it is necessary, we can grind from the inclines of the cusps. 3- We must deepen the fossa rather than removing the cusp unless, it interferes with the balancing and working occlusion. 4- For protrusive movement, we grind from the mesial and distal surface of the artificial teeth. Occlusal errors in centric occlusion and their correction a) Premature contacts which is holding remaining teeth out of occlusion, i.e any pair of opposing teeth can be too long and hold other teeth out of contact (Figure 7a). Solution: fossae of the teeth in question are deepened. The cusp tips should not be shortened (rule 3) b) The cusp tips of opposing teeth appear to be nearly tip to tip (Figure 7b). Solution: Grind on the inclines to move the upper cusp inclines buccally and the lower cusp inclines lingually. In so doing, the central fossae are made broader, the lingual cusp of the upper teeth narrowed, and the buccal cusp of the lower teeth are also narrowed. The cusp tips should not be shortened (Rule 2). c) Upper teeth too buccal in relation to the lower (Figure 7c). Solution: Broaden the central fossae. The buccal cusps of the lower teeth are moved buccally by broadening the central fossae. The cusp tips should not be shortened. A B C Occlusal errors and corrections on working side Most occlusal discrepancies found on the working side can be corrected by reducing premature contacts on the buccal cusps of the maxillary teeth and the lingual cusps of the mandibular posterior teeth (non-centric holding cusps) known as the rule of BULL (Buccals of the Uppers and Linguals of the Lowers). Occlusal errors and corrections on working side include: a) If lingual cusps made contact but the buccal cusps did not, begin grinding by removing any contacts that are present on the inclines of the lower lingual cusp (Figure 8a) b) If buccal cusps made contact but the lingual cusps did not, the lingual incline of upper buccal cusp should be ground (upper buccal cusp is shortened) (Figure 8b). c) Both upper buccal cusp & lower lingual cusp are too long. The inner inclines of both cusps should be ground (cusp's length must be reduced) (Figure 8c). d) No contact between teeth on the working side. The cause of this error is excessive contact on the balancing side. Occlusal errors and corrections on balancing side Bull rule does not work in the balancing side. Reduce interceptive cusp. Slide the articulator through working again and observe the contacts on the balancing side. Occlusal Errors and corrections on balancing side: a) Premature balancing side contacts are reduced by grinding on the lingual inclines of the lower buccal cusps. b) If there are no balancing side contacts, the working side contacts should be reduced until balancing side contacts appear. Continue until working and balancing contacts are about equal. Repeat the same sequence on the opposite side Occlusal errors and corrections on protrusive a) Premature contact in protrusive may require grinding of the anterior teeth (We grind the labial surface of the lower teeth and lingual portion of the upper anterior teeth. This grinding should be done carefully to prevent any damaging to the shape or form of the teeth and destroy the esthetic requirements) b) Equilibration in protrusive movement (Figure 6) also requires selective reduction of the non- functional cusps of posterior teeth (distal inclines of upper buccal cusps and mesial inclines of the lingual cusp of the lower teeth) until free smooth balanced protrusive movement is resulted. Upon completion of the selective grinding, the articulator should slide easily from working to balancing to protrusive side and back, this indicates that a perfect balanced occlusion is established, otherwise further corrections should be done. Instructions of the dentist to denture patients A. What to expect from your new dentures 1. You must learn to manipulate your new dentures. patient must train his musculature in holding the denture. Most patients require at least three weeks to learn to use new dentures and some patients require more time. The patient should be made aware of the limitation to tissue movements and function in advance of the treatment. Otherwise, he will not trust the operator and the quality of service. 2. The position of the tongue plays an important role in the stability of a lower denture, particularly during mastication. You should attempt to position the tongue, so it rests on the lingual surfaces of the lower anterior teeth. This will help develop stability for the lower denture. Besides, the lips and cheeks should be relaxed. 3. Dentures are not as efficient as natural teeth so you should not expect to chew as well with dentures as with your natural teeth. Dentures are better than no teeth at all. Learning to chew with new dentures usually requires at least 6 to 8 weeks. Use of dentures for chewing should be avoided for the first 3-4 days. You should begin with liquid diet followed by relatively soft food in small bites on both sides of the mouth at the same time. Do not try to bite with your front teeth. Use the area of the canine teeth to bite foods, but it is even better to cut the food into small pieces before attempting to chew. Patients, who have been edentulous without prosthesis for a long time and have learned to crush food between the residual ridges or perhaps between tongue and the hard palate, will usually take a longer time for adjustment. 4. Speaking will feel awkward for a while. Hardworking practice usually enable you with new dentures to speak clearly within a few days. Patients should be advised to read aloud and repeat words or phrases that are difficult to pronounce. 5. Soon after the insertion of dentures, salivary flow is stimulated which declines after 2-3 days. Sometimes, there is a feeling of crowding of the tongue. B. Adjustments 1. You must return to your dentist for follow-up treatment after the dentures have been inserted to make some minor adjustments to the denture. 2. If you develop soreness, do not become worried. Call your dentist for an appointment. Do not expect soreness to go away by itself. 3. If you are unable to reach your dentist during weekends or holidays, remove your dentures to prevent excess tissue damage. C. Cleaning It is important to know that successful use of dentures also depends on the maintenance of oral and denture hygiene. 1. After every meal, your mouth should be rinsed with water and your gum should be cleaned with soft brush and toothpaste. Warm saline rinses permit penetration of heat causing dilation of blood vessels which would in turn bring fresh nutrients locally contributing to accelerated repair and regeneration of tissues. 2. Denture breath is a result of dirty dentures. Dentures should be gently cleaned using soft brush and liquid detergent or soap over a bowl filled with water or wet cloth to prevent breakage in case they are dropped. You should not use toothpastes, since they contain abrasive materials that will wear away the surface of acrylic resin. 3. The dentures should be left overnight in denture cleanser to release denture plaque and stains caused by smoking and the high intake of coffee, tea and greasy food. Alkaline peroxide cleaners are the most widely used type of immersion cleaner. Their cleaning action depends on the formation of small bubbles of oxygen which dislodge loosely attached material from the denture surface. They are safe and do not damage acrylic resin or the metals used in denture construction. However, their ability to remove microbial plaque is severely limited. In addition to peroxide cleaners, hypochlorite preparations are effective disinfectants. Immersion of the dentures in a hypochlorite cleaner for more than 6 hours will result in removal of plaque and heavy staining. However, it may cause corrosion of cobalt-chromium and some loss of color of acrylic and silicone soft lining materials. 4. Sterilization of dentures with phenol containing liquids like Dettol should be avoided because it has softening effect on acrylic. Instead, soak your dentures at night in a denture cleaner or a water mouth wash solution. 5. The dentures should be placed in water when not in use in order to prevent shrinkage or warping. D. Your oral Health 1. It is desirable that oral tissues should not remain under continuous stress and therefore it is important to provide rest and natural ventilation by removing dentures from the mouth at least eight hour a day. It is advisable to remove dentures during sleeping hours which would allow tissue to recover from effect of stress as the frequent tooth contacts happened during sleep lead to the possibility that the denture bearing mucosa may be traumatized. In addition, continuous coverage of the denture-bearing mucosa prevents cleansing of the mucosa by the tongue and saliva and increases the exposure to denture plaque. 2. You need annual examinations of the supporting tissue for abnormalities and to assess the function and fit of the denture which are important for your overall dental health. The tissues that support your dentures are constantly changing. This will result in denture looseness and your dentures will need either refitting or replacement. At any event, you should call your dentist for an appointment when you notice excessive looseness.