Pontics in FPD PDF

Pontics in FPD Dr. Mohamed Tharwat El-Behairy Lecturer of fixed prosthodontics Content: Definitions Functions and requirements Pre-treatment assessment and management Classifications Factors affecting pontic design Definition : Pontic is defined as a fixed partial denture...

Pontics in FPD Dr. Mohamed Tharwat El-Behairy Lecturer of fixed prosthodontics Content: Definitions Functions and requirements Pre-treatment assessment and management Classifications Factors affecting pontic design Definition : Pontic is defined as a fixed partial denture component that replaces the lost natural tooth and restores function and appearance compatible with continued oral health and comfort. FUNCTIONS OF A PONTIC: 1) Restores mastication and articulation of speech. 2) Maintains teeth relationships both intra and interarch. 3) To satisfy patient’s esthetic needs. 4) Satisfy patient’s psychological need to eliminate space in the dentition.  Ideal Requirements: It should restore the function of the tooth it replaces. Provide good esthetics. It should be comfortable to the patient. It should be biocompatible that is it should not impinge on the tissues or should not produce any reaction on the tissues. It should permit effective oral hygiene. Easy to clean and easy to maintain. Preservation of the underlying mucosa and bone. It should not produce any ulceration in the mucosa and resorption of the residual alveolar ridge. PRETREATMENT ASSESSMENT: I. Pontic Space II. Residual Ridge Contour (Surgical Modification) III. Gingival Architecture Preservation. Pontic Space Mesio-distal and occluso-cervical space is analyzed for any drifting or tilting of teeth. In case of reduced pontic space: 1. Orthodontic repositioning 2. Small pontics (trap food and difficult to clean) 3. Increase the proximal contours of adjacent teeth better than making an FPD with under sized pontics. 4. No prosthodontic intervention Residual Ridge Contour Ideal ridge contour: 1. Should have smooth regular surface of attached gingiva 2. With adequate width and height for pontic placement. 3. Free of frenal attachment Loss of residual ridge leads to: 1. Open gingival embrasure (black triangles) 2. Food impaction 3. Percolation of saliva during speech Loss of residual ridge contour, leading to unesthetic open gingival embrasures Food entrapment (arrow) Siebert’s classified residual ridge deformities into three categories: Class I defects: faciolingual loss of tissue width with normal ridge height Class II defects: loss of ridge height with normal ridge width Class III defects: a combination of loss in both dimensions  Residual ridge deformities as classified by Siebert.2 A, Class I defect. B, Class II defect. C, Class III defect. Gingival Architecture Preservation: After tooth extraction – resorption occurs in buccal plate -- horizontal defect Bone loss averages 3 to 5 mm at 6 months after extraction; 50% of the width of the alveolar ridge is lost at 12 months* Ideal ridge contour  Alveolar architecture preservation technique. A, Atraumatic tooth extraction. B, Cross-section view of the immediate interim partial fixed dental prosthesis, demonstrating ovate pontic form.  C, Interim restoration. Note the 2.5- mm apical extension of the ovate pontic. D, The seated interim restoration should cause slight blanching of interdental papilla.  E, Interim restoration 12 months after extraction Pontic modifications 1. Patient’s inability to undergo surgery because of cost. 2. Patient’s with medically compromised condition. 3. Ridges with severe defects, where 2 or more pontics must be used to fill the space. 1. Gingival masks ? 2. Andrews bridge system ?  Gingival masks A gingival mask, sometimes called a gingival replacement prosthesis, is a type of artificial gum. It provides dramatic cosmetic improvements in patients who have receding gums or have lost gum tissue from untreated conditions. Andrews bridge system The indications for fixed-removable Andrew's Bridge system are tooth loss along with the defect in the edentulous ridge, (failure of fixed partial denture because of long edentulous space, the removable partial denture has failed due to discomfort related to its palatal extension). It requires a castable bar and sleeve attachment, which provides precision and retention while seating. It is primarily indicated where abutments are capable of supporting a fixed partial denture, but residual ridge shows severe loss. Case.1 Case.2 Classification of Pontics A- Construction technique 1-Prefabricated pontic: 2-Custom-made pontic: B- Pontic materials 1. Metallic 2. Non-metallic: All-ceramic Acrylic resin Fiber-reinforced resin 3. Metal-ceramic C- Relation to the mucosa: 1.Mucosal contact: Ridge lap Modified ridge lap Ovate Conical 2.No mucosal contact: Sanitary or Hygienic Pontic Modified sanitary (hygienic) Saddle or ridge lap pontic: The saddle pontic has a concave fitting surface that overlaps the residual ridge buccolingually, simulating the contours of the missing tooth on both sides of the residual ridge. Advantages: Disadvantages: Esthetics Saddle or ridge lap designs should be avoided because the concave gingival surface of the pontic is not accessible to cleaning with dental floss lead to Plaque accumulation Tissue inflammation.  Dental floss A, Cross-section view of ridge lap pontic. B, The tissue surface is inaccessible to cleaning devices.  Modified ridge lap pontic It combines the best features of the hygienic and saddle pontic designs, combining esthetics with easy cleaning. It overlaps the residual ridge on the facial (to achieve the appearance of a tooth emerging from the gingiva) but remains clear of the ridge on the lingual to enable optimal plaque control. The modified ridge lap design is the most common pontic form used in areas of the mouth that are visible during function Maxillary and mandibular anterior teeth Maxillary premolars and first molars.  To enable optimal plaque control, the gingival surface must have no depression or hollow. Rather, it should be as convex as possible from mesial to distal aspects (the greater the convexity, the easier the oral hygiene). CONICAL PONTIC: Often called egg-shaped, bullet-shaped, or heart-shaped. It is convex in all directions with only one point of contact at the center of the residual ridge. This design is recommended for the replacement of mandibular posterior teeth where esthetics is a lesser concern and presence of thin knife edge ridge.  CONICAL PONTIC A, Conical pontics may create food entrapment on broad residual ridges (arrow). B, The sanitary pontic form may be a better alternative. OVATE PONTIC: The ovate pontic is the most esthetically appealing pontic design. Its convex tissue surface resides in a soft tissue depression or hollow in the residual ridge, which makes it appears that a tooth is emerging from the gingiva. It requires faciolingual width and apicocoronal thickness. Advantages: 1. Its pleasing appearance when used successfully with ridge augmentation, its emergence from the ridge appears identical to that of a natural tooth. 2. It is not susceptible to food impaction. 3. Because the tissue surface of the pontic is convex in all dimensions, it is accessible to dental floss. ❖ The ovate pontic design eliminates the potential for unsupported porcelain in the cervical portion of an anterior pontic. Disdvantages: 1. Meticulous oral hygiene is necessary to prevent tissue inflammation resulting from the large area of tissue contact. 2. The need for surgical tissue management and the associated cost. Recommended location: Maxillary incisors, cuspids and premolars Contraindication: Patients unwillingness for surgery SANITARY OR HYGIENIC PONTIC 1.Design: No contact with residual ridge Occluso-gingival thickness greater than 3mm Adequate space for cleansing advantages: Good access for oral hygiene Least tissue inflammation Disadvantages: Poor aesthetics Recommended location: Non appearance zone Contraindication: Appearance zone Less vertical dimension MODIFIED SANITARY PONTIC A modified version of the sanitary pontic. It is also less susceptible to tissue proliferation that can occur when a pontic is too close to the residual ridge. Its gingival portion is shaped like an archway between the retainers leads to: Increase connector size Decrease the stress concentration on the pontic and connectors It is called arc-FPD  Factors affecting pontic design BIOLOGIC Cleansable tissue surface Access to abutment teeth No pressure on ridge MECHANICAL Rigid (to resist deformation) Strong connectors (to prevent fracture) Metal-ceramic framework (to resist porcelain fracture) ESTHETIC Shaped to look like tooth it replaces Appears to “grow” out of edentulous ridge Sufficient space for porcelain  BIOLOGIC CONSIDERATIONS Pontic has to preserve the Residual ridge Abutment Opposing teeth. Factors of specific influence are : 1. Pontic ridge contact. 2. Plaque control and oral hygiene measures. 3. Pontic material. 4. Occlusal forces 1- PONTIC RIDGE CONTACT Pressure-free contact between the pontic and the underlying tissues is indicated to prevent ulceration and inflammation of the soft tissues. If any blanching of the soft tissues is observed at try-in, the pressure area should be identified with pressure-indicating paste and the pontic recontoured until tissue contact is passive. Contact should be on keratinized attached tissue 2- ORAL HYGIENE CONSIDERATIONS The chief cause of ridge irritation is the toxins released from microbial plaque, which accumulate between the gingival surface of the pontic and the residual ridge, causing tissue inflammation and calculus formation. Patients must be taught efficient oral hygiene techniques, with particular emphasis on cleaning the gingival surface of the pontic. Devices such as proxy brushes, super floss, and dental floss with a threader are highly recommended.  To prevent food accumulation and allow oral hygiene measures the following is done: 1. Gingival embrasures around the pontic should be wide enough to permit oral hygiene aids. 2. Tissue contact between the residual ridge and pontic must be passive to permit passage of floss over its entire tissue surface. 3. Avoid using saddle pontic design: If the pontic has a concavity in its gingival surface, plaque will accumulate, because the floss cannot clean this area, and tissue irritation will follow.  3- PONTIC MATERIAL Any material chosen to fabricate the pontic should be biocompatible. Biocompatibility of materials used to fabricate pontics centered on two factors: 1. The effect of the materials 2. The effects of surface adherence.  Glazed porcelain is generally considered the most biocompatible of the available pontic materials. Well polished is smoother, less prone to corrosion, and retentive plaque of than an unpolished or porous casting is generally considered the most biocompatible of the available pontic materials. Resin should not be used because of its porous nature and difficulty to maintain highly polished surface  4- OCCLUSAL FORCES Pontics with normal occlusal widths are generally recommended. Reducing the buccolingual width of the pontic by as much as 30% has been suggested as a way to lessen occlusal forces and the loading of abutment teeth. Harmful forces are encountered if a FPD is loaded by the accidental biting on a hard object or by parafunctional activities like bruxism.  MECHANICAL CONSIDERATIONS The prognosis of fixed partial denture pontics will be compromised if mechanical principles are not followed closely. Mechanical problems may be caused by: Improper choice of materials, Poor framework design, Poor tooth preparation, Poor occlusion. These factors can lead to fracture of the prosthesis or displacement of the retainers. For example Long-span posterior FPDs are susceptible to mechanical problems. There is significant flexing from high occlusal forces. So, a strong all- metal pontic is needed in high-stress situation rather than a metal-ceramic pontic, which is more susceptible to fracture  ESTHETIC CONSIDERATIONS The patient will evaluate the result by how it looks, especially when anterior teeth have been replaced. An esthetically successful pontic will replicate 1. Form 2. Contours 3. Incisal edge 4. Embrasures 5. Color of adjacent teeth  GINGIVAL INTERFACE The pontic's simulation of a natural tooth is most challenging at pontic tissue interface After a tooth is removed, the alveolar bone undergoes resorption and/or remodeling. If original tooth contour is followed, pontic looks unnaturally long inciso-gingivally A, Esthetic failure of a four-unit partial fixed dental prosthesis (FDP) replacing the right central and lateral incisors. The pontics have been shaped to follow the facial contour of the missing teeth, but because of bone loss they look too long. B, The replacement FDP. Note that the gingival half of each pontic has been reduced. Esthetic appearance is much improved. C, This esthetic failure is the result of excessive reduction. The central incisor pontics look too short.  To achieve the illusion of a natural tooth, an esthetic pontic must deceive observers into believing they are seeing a natural tooth. Special attention should be directed to the contour of the labial surface as it approaches the pontic-tissue junction, to achieve a “natural” appearance. The modified ridge-lap pontic is recommended for most anterior situations; it compensates for lost buccolingual width in the residual ridge by overlapping what remains, rather than emerging from the crest of the ridge as a natural tooth would.  When appearance is of utmost concern, the ovate pontic, used in conjunction with alveolar preservation or soft tissue ridge augmentation  If a pontic is poorly adapted to the residual ridge, there will be an unnatural shadow in the cervical area that looks odd and spoils the illusion of a natural tooth. The second premolar pontic is successful because it is well adapted to the ridge; the first premolar is evident because of its poor adaptation to the ridge,  In moderate bone resorption : Shape the pontic to simulate a normal crown and root with emphasis on the cemento-enamel junction. The root can be stained to simulate exposed dentin. 2- Use pink porcelain to simulate gingival tissues  PONTIC DESIGN Pontic design Appearance Recommended location Advantages Disadvantages Indications Contraindications Materials Non esthetic Where esthetics is Sanitary/ Good access for Posterior mandible Poor esthetics zones Impaired important Minimal All metal hygienic oral hygiene oral hygiene vertical dimension Saddle- Not amenable to Not Not recommended Esthetic Not recommended Not applicable ridge-lap oral hygiene recommended Posterior areas Molars without esthetic Good access for where esthetics All-metal Metal- Conical Poor esthetics Poor oral hygiene requirements oral hygiene is of minimal ceramic All-resin concern High esthetic requirement Most areas with Where minimal Metal-ceramic Modified Good Moderately (i.e., anterior teeth and premolars, esthetic esthetic concern All-resin All ridge-lap esthetics easy to clean some maxillary molars) concern exists ceramic Superior esthetics Requires surgical Very high esthetic requirement Desire for Unwillingness for Metal-ceramic Negligible food Preparation Not Maxillary incisors, canines, and optimal surgery All-resin Ovate Entrapment Ease for esthetics Residual ridge premolars of cleaning Residual ridge All ceramic High smile line defects defects