Relining And Rebasing Of Complete Dentures

Relining And Rebasing Of Complete Dentures

Question. Explain the various relining techniques and add a note on the advantages and disadvantages of each technique.
Answer:

Various relining techniques There are two major relining techniques:

• Open-mouth
• Closed-mouth.

Various relining techniques Indications for Relining or Rebasing

• Immediate dentures at three to six months after their original construction.
• When the residual alveolar ridges have resorbed and the adaptation of the denture bases to the ridges is poor.
• When the construction of new dentures with the accompanying series of appointments can cause physical or mental stress, such as for geriatric or chronically ill patients.
• When the patient cannot afford the cost of having new dentures constructed.

Read And Learn More: Complete Dentures Question and Answers

Various relining techniques General considerations

• The occlusal vertical dimension should be satisfactory.
• The centric relation should coincide with centric occlusion.
• Oral tissue should be in optimum health.
• Denture base extension should be adequate.
• Inter-occlusal distance should be correct,

Various relining techniques Contraindications

• When an excessive amount of resorption has taken place.
• When abused soft tissues are present.
• When the patient complains of TMJ problems.
• If the dentures have poor esthetics.
• If the dentures create major speech problems.

Various relining techniques Steps in Relining Technique

Various relining techniques Tissue Preparation

• Excessive hypertrophic tissue should be surgically removed. The dentures can be used as a surgical splint.
• The oral mucosa should be free of areas of irritation.
• Removal of the dentures from the mouth during sleep is a must for several weeks before treatment commence.
• The dentures should be left out of the mouth at least two or three days before making the final impression.
• Daily massage of the soft tissues is helpful to stimulate their blood supply.

Various relining techniques Denture Preparation

• Pressure areas on the tissue surface of the dentures should be relieved.
• Minor occlusal disharmony is corrected by selective grinding.
• Small border inadequacies are corrected.
• A correct posterior palatal seal area should be established before the final impression. Stick compound and auto-polymerizing acrylic resin can be used for this purpose.

Various relining techniques Factors to Take Care of During Relining

• Do not increase the occlusal vertical dimension.
• Multiple even contacts (maximum intercuspation) should be present in centric relation.
• Do not permit the maxillary denture to move forward during impression-making.
• Ensure that centric relation and centric occlusion are identical.
• Ensure that an accurate posterior palatal seal has been established.
• An equal thickness of the final impression material should be used.

Various relining techniques Closed-Mouth Relining Techniques – Maxillary Denture

Done using the existing centric occlusion and intercuspation of the dentures. The various techniques in the closed mouth are

Technique A

Technique A Centric relation is recorded before the impression is made, using the medium of choice (modeling compound or wax).

Technique A Denture preparation Denture is relieved of all large undercuts and a space of 1.5–2 mm is made on the tissue surface for impression material. The borders are reduced 1–2 mm except for the posterior border of maxillary dentures.

A large part of the middle of the palatal portion of the maxillary denture is removed for visibility in positioning the maxillary denture during impression-making.

Technique A Border molding Borders of the dentures are reformed to their functional contours by using a low-fusing modeling compound.

Technique A Impression Zinc oxide-eugenol impression paste is used. During the border molding and impression making, the patient closes lightly into the premade interocclusal record. The impression of the exposed part of the palatal section is made with quick-setting plaster.

Technique A Advantages

• The opening of the palatal portion will allow better seating of the maxillary denture and alleviate the increase in the vertical dimension.
• The premade interocclusal record helps to position the dentures during the impression-making and to orient the dentures on the articulator.
• The two-step impression technique will reduce the possibility of moving the maxillary denture forward during the final impression-making.

Technique A Disadvantages

• The possibility of moving the maxillary denture forward is still a major problem.
• The wax interocclusal record is not an accurate and safe record This technique does not suggest any solution for the difficulties of relining both dentures at the same time.

Technique B

Technique B Centric relation Existing centric occlusion and intercuspation are used as a means to seat the dentures.

Technique B Denture preparation The same as for technique A. For easy removal of the palatal portion, the outline of the area is drawn and deepened on the polished surface up to half the thickness of the base. Holes are drilled at 5- to 6-mm intervals inside this groove.

Technique B Border molding Low-fusing modeling compound (green stick) is suggested for border molding.

Impression Kerr’s impression wax (Iowa wax) is the material of choice in this technique. The impression is made in two steps. The impression of the labial flange and the crest of the alveolar ridge between the canines is made as a second step.

Technique B Advantage

The two-step impression technique will reduce the possibility of extreme forward movement of the maxillary denture.

Technique B Disadvantages

• Wax impression material is difficult to work with and the possibility of distortion exists.
• Errors of existing centric occlusion can produce an inaccurate impression.

Technique C

Technique C Centric relation Same as in technique B.

Technique C Denture preparation Same as in techniques A and B. The labial and palatal flanges of the denture are perforated. The perforations will decrease the pressure inside the denture during the impression-making procedure, thereby preventing displacement of a maxillary denture.

Technique C Border molding is The same as techniques A and B.

Impression No specific impression material is recommended.

Technique C Disadvantages

The same as in techniques A and B.

Technique D

Technique D Centric relation The existing centric occlusion is used to seat the maxillary denture.

Technique D Denture preparation The same as in the other technique.

• The denture periphery should be shortened to create a flat border.
• A large opening should be prepared in the palatal portion of the maxillary denture.
• Adhesive tape is attached over the buccal and labial surfaces of both dentures 2 mm away from the denture borders.
• With a knife-edge stone, a fairly deep groove should be cut into the buccal and labial surfaces of the dentures at the junction of the impression material and filled with molten baseplate wax.

Technique D Border molding During the impression making it has been emphasized that a slight amount of impression material should be left on the flattened borders.

Technique D Impression Plaster of Paris or zinc oxide-eugenol is suggested for the first step of impression making, and plaster of Paris for the second step (the palatal portions).

Technique D Advantages

The same as in technique A.

Technique D Disadvantage

Even though it has been suggested that the patient should not seat the denture by closing on it, the existing errors of centric occlusion may produce some pressure points and a faulty impression can result.

Technique D Closed-Mouth Relining Technique–Mandibular Denture

Technique E

Technique E Centric relation Existing centric occlusion is used as a means to seat the mandibular denture during the secondary impression. The occlusion is corrected during the establishment of a new occlusal vertical dimension.

Technique E Denture preparation Loss of vertical dimension is corrected by luting softened modeling compound to the occlusal surfaces of the mandibular posterior teeth.

• The patient is directed to repeatedly pronounce the letter “m”. The record is chilled, trimmed, and slightly heated before returning it to the patient’s mouth.
• The procedure is repeated until the occlusal vertical dimension is established to the operator’s satisfaction. The denture is luted to the maxillary denture in maximum intercuspation.
• A softened modeling compound is placed inside the mandibular denture and the articulator is closed against the lower cast to contact the incisal guide pin.
• With this procedure, the amount of vertical dimension indicated by the thickness of the compound on the surface of the mandibular teeth is transferred to the base of the mandibular denture. The mandibular denture at this stage is used as a tray for making the final impression.

Technique E Impression Modeling compound at the early stage and zinc oxide-eugenol for making the secondary impression is suggested.

Technique E Advantages

• The loss of vertical dimension can be compensated for during the relining procedures.
• The error in centric occlusion can be reduced during the laboratory stages.

Technique E Disadvantages

• This technique is very time-consuming from the standpoint of clinical and laboratory procedures.
• The procedure for the establishment of occlusal vertical dimension is highly questionable.

Technique E Open-Mouth Impression Technique

Boucher’s technique (technique F) is the only one that explains a method for relining the mandibular and maxillary dentures at the same time.

Technique F

• Centric relation Utilizing both dentures as recording bases, the jaw relation is recorded after making the secondary mandibular and maxillary impressions.
• Denture preparation A posterior palatal seal is formed in the modeling compound on the maxillary denture. One millimeter of space is provided inside the denture for the new impression material. The borders are shortened by 1 mm to allow space for the impression material to form a new border.
• In the lower denture, the buccal surfaces of the lingual flanges are ground to minimize the pressure against the mylohyoid ridges and between the tissues of the floor of the mouth and buccal sides of the lingual flanges.
• The lingual flange between the mylohyoid eminences is shortened by 1 mm. The labial flange between the buccal notches is shortened by 1 mm.
• Two grooves are cut on the buccal sides of the lingual flanges to facilitate the removal of the retro mylohyoid eminences after the cast is poured.
• A modeling compound handle formed over the lower anterior teeth facilitates handling the denture when it is carried to the mouth. Adhesive or masking tape is adapted over the polished surfaces of both dentures and over the teeth.
• Border molding If the flanges are inadequate, the borders should be corrected with a modeling compound.
• Impression Zinc oxide-eugenol impression material in which the patient is asked to pull his upper lip down and to open his mouth wide.
• These actions mold the impression material over the border of the denture. The upper denture is laid aside until the lower impression has been made.

Technique F Advantages

• The special trimming of the denture and making room for the impression material will facilitate the making of a reasonable impression during the selective pressure impression technique without any occlusal interference.
• A separate interocclusal record using already made impressions as the recording bases will allow the operator to concentrate on recording the jaw relation.
• It is possible to verify the centric relation record, if necessary.
• The interocclusal record, which is made with quick-setting plaster, is a reliable one.

Technique F Disadvantage

• The technique requires more clinical and laboratory time.

Technique F Suggested Technique

Functional impression with fluid resin (tissue conditioning material).

Technique F Clinical Procedures

• Dentures are not to be worn overnight before impression making.
• Examination of old dentures for errors of occlusion and centric occlusion (maximum intercuspation).
• The basal surface of the denture is reduced to allow room for the tissue conditioning material.
• This surface is dried before the material is placed into the denture.
• A minimum thickness of tissue conditioning material is placed over the tissue surface of the denture.
• After removal from the mouth, the tissue conditioner is trimmed to remove all excess material.

Technique F Instructions were given to the patient on the care of resilient liners

• When the patient returns to the dentist after three to five days, the denture should be examined for denuded areas. Mark the denuded areas with an indelible pencil and relieve the pressure areas on the denture before the next application of tissue conditioner.
• Underextended borders should be corrected with impression compound before the next application of the material.
• The material is never allowed to remain in a denture for more than a week, as the material itself may become a source of irritation.
• When the tissue has returned to a clinically discernible healthy state, the patient is scheduled for making impressions.
• All of the tissue conditioning material on the tissue surface of the dentures should be replaced with new impression material.
• The patient is instructed to wear the dentures for 3 minutes while in the waiting room and he or she may eat a light meal if desired.
• If there are no pressure areas, this impression could be considered as a master impression for relining the dentures.

Technique F Laboratory Procedure

• After the final impression is made, a cast must be poured immediately.
• Mount the maxillary cast on a semi-adjustable articulator using the face-bow transfer record.
• Relate the mandibular denture to the maxillary denture, which is already mounted on the articulator, using an interocclusal record.
• If an occlusal discrepancy exists, it should be corrected before separating the impressions from the casts, by using a selective grinding procedure.
• The procedures of relining and rebasing are the same until this stage. During the laboratory phase of a rebasing procedure, the entire old denture base is replaced by new material without changing the arrangement of the teeth.
• The presence of all porcelain teeth greatly facilitates a rebasing procedure. If resin teeth are present, relining is usually indicated, as it is difficult to rebase a denture with resin teeth.
• When the dentures are finished, plaster remount casts are made and the maxillary cast is mounted on the articulator.

Technique F Insertion Procedure

• Use a pressure-indicating paste to locate pressure areas. They are carefully relieved by grinding with mounted stones.
• A new interocclusal record is used to mount the lower denture in centric relation.
• It is necessary to verify the mounting before adjusting the occlusion.
• With a selective grinding procedure, occlusion can be preferred at the correct occlusal vertical dimension.
• Before dismissing the patient at the initial placement visit, check the occlusion once again.