Single DenturesSingle Upper Dentures Opposing: Single Lower Dentures Opposing:Upper Natural Dentition Natural dentitionPartial lower denture
Difficulties of Maxillary Single Denture Against Dentate Mandible Occlusal discrepancies Excessive load Combination syndrome Denture fracture Teeth abrasion Esthetic limitation
The Subsequent problems with single denture against natural teeth 1- Great force generated by the natural teeth. 2- The occlusal form of the remaining natural teeth (malposed, tipped, or super erupted teeth in the lower arch) make it difficult to achieve a harmonious balanced occlusion.3- Excessive pressure result in resorption of the residual ridge & hyperplastic tissues.4- Combination syndrome and associated changes.
Upper Single against Lower Dentate ArchRight working Maxillary Denture Opposing Dentate Mandible Centric occlusion The patient wore this denture for more than 10 years resorption of the maxilla and the wear associated with the posterior mandibular dentition (specially when porcelain teeth were used). Note the patient in the right working position. There are no balancing contacts on the opposite side. Resorbed maxilla
How To Overcome These Problems The primary consideration for a continued success of a single complete denture is the preservation of that which remains: Proper diagnosis and full use of every factor, which favor success for this denture. Applying the principles of CD construction .Maximum base extension within functional anatomical limits (distributed forces over the largest possible area of supporting structures and the force per unit area kept at minimum).Reduction of the forces to which the denture is subject.
Steps for Single Denture construction Proper Diagnosis and mounting the diagnostic casts.Occlusal Adjustment and Tooth ModificationFinal Impression. Jaw relation.Face bow transfer. Artificial teeth arrangement, adjustment and Try-in of waxed denture.Delivery.
Diagnosis check-outInclude the checking of: Ridge relationshipInter-dental spaceOcclusal planeSpaces Proper Diagnosis: Tooth positionCuspal inclinationRotationsTooth wear
Occlusal Plane Adjustment&Tooth ModificationOcclusal Plane Discrepancies The occlusal plane discrepancy is readily apparent when the denture teeth are properly arranged. This discrepancy can only be corrected by restorative means.
Tooth Reduction Protocol Confirm pulpal maturity (X-rays, EPT)No anesthesiaBegin with teeth requiring most reduction
Preparing Plane of Occlusion Individual Tooth ModificationsSharp Unworn Cusps Reduce cuspal inclination.Heavily Abraded Teeth Reduce Bu-Li width.
Tooth modifications and occlusal adjustment I- Swenson’s TechniqueII- Bruce TechniqueIII- Yurkstas’ TechniqueIV- Boucher’s TechniqueV- Custom Template-Resin Techniques
Swenson’s Technique Denture teeth are set and when the natural teeth interfere with placement of denture teeth, stone teeth are adjusted and marked on the cast with pencil.The natural teeth are modified by using the diagnostic cast as a guide.
Bruce Technique The Modifications are made on the stone cast. A clear acrylic resin template is fabricated over the modified stone cast & with pressure indicated past on the internal surface of it , the unfavorable areas are shown remove them.
The interferences are removed by movement of the maxillary porcelain teeth over the mandibular stone teeth. Prematurity's are identified and removed by grinding the natural teeth. The procedure is repeated for right and lateral excursions until a harmonious balanced occlusion is established. Boucher Technique
The use of a metal U-shaped occlusal template that is slightly convex on the lower surface is placed on the occlusal surfaces of the remaining teeth. 20° Template Yurkstas Technique
Custom Template – ResinTechniquesCommon Occlusal Disharmonies
1) Completely edentulous maxilla opposing a mandibular complement of natural teeth with missing first molars, or second premolars, or both . a) If the molars are not severely tilted or over erupted they may be reshaped by selective grinding. b)When more than a moderate amount of tooth reduction is found necessary, the ideal treatment is to restore the tilted molars with cast gold crowns, onlays, or a fixed bridge with or without RCF.
d) If the molars are severely tilted forward and supererupted, and modification is not possible, extraction is necessary. c) If a large space does exist mesial to the tilted molars, another alternative treatment is to design a removable partial denture that would restore the mesial half of the molars by using an onlay mesial rest.
Artificial Teeth ArrangementAnterior Tooth Arrangement of Single Denture Lip supportMinimal vertical overlap (Overbite)Protrusive balance Ensure:
Posterior Tooth Arrangementof Single Denture “An occlusal scheme that employs a multiplicity of point contacts, rather than one that utilizes broad-surfaced contacts on inclined planes is advocated”. John J. Shary
Harmonious balanced occlusion in a single denture can be achieved either by: I - Statically equilibrated occlusion using a programmed articulator to stimulate the patient’s mandibular movements. a- Articulator equilibrated technique. b- Articulator generated path technique.II - Dynamically equilibrated occlusion by the use of functional generated path technique (Functional chew-in techniques) Methods Used To Achieve Balance Articulation:
Statically equilibrated occlusiona-Articulator equilibrated technique: Equal contacts in centric occlusion and no interferences in excursive movements & avoid broad inclined planes Semi adjustable articulator.Lingualized occlusion.Balanced sliding occlusion (free articulation).Monoplane occlusion.
Statically equilibrated occlusion a- Articulator equilibrated technique.Statically equilibrated occlusion b- Articulator generated path technique before after By using a cavity preparation in the occlusal surface of artificial teeth, like Class I. filled with amalgam like material, that altered according to articulator functional movements which simulate the chewing action of human , as much as possible.
Dynamically equilibrated occlusion:Functional generated path technique (Stansbury, 1928) An upper bit-rim of compound (preserve VD), that trimmed buccaly & lingually for lat. freedom movements, covers with Carding wax that molded inside patient’s mouth (developing functional occlusion path).Pouring the Carding wax with stone give us a model represent the functional path of lower natural teeth.Arranged upper teeth first related to conventional lower teeth, then to the lower model represents the “functionally generated occlusion”.
Functional generated path technique (Stansbury, 1928)Artificial Teeth Materials & Types
Artificial Tooth Material Plastic (acrylic , cross linked resin )PorcelainMetal (casted)Acrylic with gold occlusal surface, or amalgam stoppers.
1- Porcelain teeth : Wear very slowly and therefore the occlusal vertical dimension is maintained but, cause rapid wear of opposing natural teeth and may be exposed.2- Acrylic resin teeth : No wear of the opposing natural teeth, they are the teeth of choice. The major disadvantage of resin teeth is their wear, which results in loss of vertical dimension.
3- Acrylic resin with gold occlusal surfaces: although gold occlusals are considered the best material to oppose natural teeth, their expense and the time involved in their fabrication. 4- Acrylic resin with amalgam stops:reduce the occlusal wear, and the technique is simple less time consuming and less expensive than with the gold occlusals. 5- Cross-linked resin : The wear resistance is higher than that of the conventional acrylic resin teeth.
Single DentureSupported byImplantsImplant Assisted Overlay Maxillary Dentures Against lower natural teeth Occlusion is bilateral balance in such patients
Upper Single against Lower Natural AnteriorsSingle denture opposing distal extension RPD
Protrusive position Resorbed premaxilla Centric occlusion The vertical overlap of the anterior teeth was excessive and with the patient in the protrusive position there are no posterior contacts. As a result the denture is tipped anteriorly during the function severe resorption of the premaxilla (combination syndrome). Single denture opposing distal extension RPD
Combination Syndrome A specific pattern of resorption when anterior mandibular teeth are retained and are opposed by a complete maxillary denture. The premaxilla undergoes severe resorption and is usually accompanied by the development of fibrous hyperplasia of the maxillary tuberosity.
When mandibular anterior teeth remain, patient will attempt to function in protrusive relationship top sense feeling of mastication. Combination Syndrome
Combination SyndromeResorbative Changes Occur In The Maxillary Anterior Ridge Settling Of the maxillary anterior denture base V. D. O. will begin to decrease lowers the posterior O. P. as maxillary denture moves superiorly and anteriorly. As bone is resorbed from maxillary anterior ridge, denture will tip upward anteriorly and downward posteriorly.
The change in the angulation of the occlusal plane may result in a protrusive or sliding contact of the mandibular teeth with the denture, which can contribute to the loss of support for the remaining natural teeth or precipitate periodontal changes.
The labio-buccal flange of the denture produces a low grade irritation in the surrounding soft tissues, resulting in development of Epulis Fissuratum, and cause an associated overgrowth of fibrous tissue covering the maxillary tuberosities.
The Combination Syndrome is a Result of Three Main Factors The great magnitude of forces involved.The unsuitability of the denture foundation to resist them. Particularly unfavorable occlusal relationship.
With some careful grinding of the canines we can produce a bilateral balanced occlusion Single denture opposing distal extension RPD
In this patient occlusal rests have been used to idealize the occlusal plane. The incisal angle and the angle of the balancing ramp are compatible and bilateral balance is maintained. Single denture opposing distal extension RPD
Osseointegrated Implants Overlay Denture against Lower Partial Arch Implant assisted overlay dentures are recommended for the maxilla when opposed by natural dentition in the mandible (full or partial). The implants prevent tipping of the denture anteriorly and also provide additional retention and stability. Although the implants prevent tipping of the denture and provide support for the denture in the anterior region, the occlusion should still be designed to provide bilateral balance. Otherwise, the excessive tipping forces and lateral loads will lead to an excessively high implant loss rate.
Note: Resilient attachments on the distal sides of the bar bilaterally, are preferred. Osseointegrated Implants Overlay Denture against Lower Partial Arch
Implant Supported overlay dentures are preferred to fixed protheses. However 6 or more implants with at least 2 cm of anterior spread must be used to achieve a predictable result. Advantages:Lip support and estheticsCostSpeech articulation Osseointegrated Implants Overlay Denture against Lower Partial Arch To maximum results the lower also replaced with implant supported Prosth.
Surgical Prosthetic Correction of COMBINATION SYNDROMESEQUENCE FOR ONE APPOINTMENT SURGICAL TREATMENT PRE-SURGICAL/ PROSTHETIC PLANNING:2. SURGICAL/ PROSTHETIC PHASE: a. Maxillary Soft Tissue Graft with Hydroxylapatite for Reconstruction of resorbed ridge, with upper immediate denture ready for insertion (not loaded). b. Extractions, alveoplasty & insertion of mandibular implants (immediate lower denture & soft liner are ready to be used).
As Conclusion:Strategies for prevention of resorption Correct occlusal discrepancies: a) Reshaping by grinding. b) Reshape with RPD framework. c) Provide new restorations, if possible.Retain root tips particularly in the premaxilla to facilitate support (over denture planed).Place osseointegrated implants to facilitate support. Avoid excessive vertical overlap of the anterior denture teeth.
Esthetic and phonation difficulties. Abrasion of the artificial teeth if acrylic is used, or the abrasion of natural teeth if porcelain is used. Increase the tendency of fracture of maxillary denture due to occlusal stresses exerted by natural teeth. The implant can not conceder in the treatment plan….then preferred to converted to C.D. IF the presence of natural lower anterior teeth cause:
Lower Single against Upper Dentate ArchEdentulous Mandible Opposing Dentate Maxilla Difficulties:Excessive loadOcclusal problemsFracture Tooth wear Tissue abuse Increased monitoringMinimal denture foundation area
In the mandible, the limited denture bearing area will lead to advanced residual ridge resorption of the edentulous mandible. For this reason, a lower complete denture opposing upper natural teeth should be avoided . A lower complete denture opposing upper natural teeth is acceptable for patients with class III jaw relation. and for a patient with cleft palate. Edentulous Mandible Opposing Dentate Maxilla
Edentulous Mandible Opposing Dentate Maxilla Conventional dentures are contraindicated because they cause severe resorption as seen in this patient. In past years many prosthodontists recommended extraction of the remaining maxillary teeth. Today other options are available.
Maximize denture base coverageMinimized occlusal forcesPreprosthetic surgeryRetention of key rootsUse of osseointegrated implantsTemporary soft liners replaced on a regular basis Permanent soft liners Options other than extraction of maxillary dentition For Preservation of the Residual Alveolar Ridge Edentulous Mandible Opposing Dentate Maxilla
You should also…..1. When construct the lower denture restoration, should Leveling the upper occlusal plane: by extraction, grinding of cusps, crowns or occlusal build-ups
2. Lower Ridge Augmentation is done, if the lower R.R. was so resorbed.3. Retained Roots Supported Over Denture Retaining roots in key positions facilitate support and prevent compression of the periosteum. Be caution that:The excessive loads delivered to these areas will result in continued resorption of the mandibular body.
4. Osseo-integrated Implants assisted overlay dentures opposing dentate maxilla The implants are used to facilitate retention, stability, and provide support in the anterior region. Posterior occlusal loads, however, must be borne by the retromolar pad, the buccal shelf and the residual alveolar process. A carefully made border molded impression will make maximum use of these support areas.
Osseo-integrated Implants Opposing Dentate Maxilla Implant supported prostheses – All the occlusal forces are borne by the implants This type of prosthesis stops the process of resorption of the mandible. It is therefore the most desirable method for restoring the edentulous mandible that opposes a fully dentate maxilla.
Questions for Review Name the five factors affecting occlusal balance. (10 points)Why is it difficult to achieve bilateral balance with a complete denture that opposes an intact dentate arch? (6 points)Define combination syndrome. (4 points)In the past many prosthodontists recommended extracting the remaining maxillary teeth when opposed by an edentulous mandible. Why? What are the options available today? Which option is preferred and why is this option preferred? (14 points)Discuss in detail the strategies you would use when restoring an edentulous arch that opposes a fully dentate arch to prevent or minimize resorption of the edentulous arch. ( 10 points)When fabricating a maxillary denture opposing a fully dentate mandibular arch what are the consequences of arranging the maxillary anterior denture teeth with excessive vertical overlap? (4 points)
Typical examination questions in an organized summary, discuss the problems of the single denture wearer and possible solutions to specific problems (15) discuss the problems faced by the patient wearing a specific type of single denture and propose strategies to cope with the problems(6)