Periodontal Considerations (PDF)

‫بســـم هللا الرحمــن الرحيم‬ PERIODONTAL ASPECTSS IN FIXED PROSTHODONTICS  Patients Healthy Periodontally periodontium compromised Treat the condition...

‫بســـم هللا الرحمــن الرحيم‬ PERIODONTAL ASPECTSS IN FIXED PROSTHODONTICS  Patients Healthy Periodontally periodontium compromised Treat the condition Preserve the condition Arrest its progress Restoration that will not insult Establish a regimen of strict oral hygiene Use a restoration to preserve heathy the attachment apparatus attachment apparatus of abutment tooth Design features of the different surfaces of the fixed prosthesis that may influence directly or indirectly the periodontal health of the surrounding tissues. 1.Axial Crown Contours. 2.Crown Margin. 3.Pontic Design. 4.Bridge design. 5.Occlusal Morphology. Periodontium: A connective tissue structure attached to periosteum, anchors the teeth in the mandibular & maxillary alveolar process. 1. Gingiva a. Free marginal gingiva b. Attached gingiva c. Interdental papillae 2. Periodontal ligament 3. Alveolar bone.  Gingival crevice (sulcus) → Normal depth → 1-2 mm. Epithelial attachment → 1 mm. Connective tissue attachment → 1 mm. Alveolar crest → It is located 2 mm apical to the base of the sulcus.  Biologic width: The combined width of connective tissue and junctional epithelial attachment formed adjacent to a tooth and superior to the crestal bone. The biologic width allows gingival fibres to establish direct contact with the tooth and acts as a barrier to prevent penetration of microorganisms in the sulcus into the underlying periodontal tissues  Periodontal ligament: Collagen fibers grouped in bundles embedded in alveolar bone & cementum. Support the tooth during function & anchors it to the jaw. Healthy periodontal ligament in functional occlusion is 0.25mm. wide. Widest at the margin and apex and narrower in the middle Functions of the periodontal ligament: 1. Supportive function: Connects the tooth to the alveolar bone Supports the tooth in its socket during function. 2. Socket absorbing function: P.L. fibers withstand forces applied parallel to the long axis of the tooth. (absorbs axial forces)→ protects tooth especially at the apex. Lateral (horizontal) & rotational forces are less absorbed. On tension side fibers are extended & on the pressure side fibers are compressed. Bone resorption in areas of pressure & bone formation in areas of tension. 3. Formative function: P.L. acts as a reservoir, mesenchymal cells differentiate into: Osteoblasts Cementoblasts Fibroblasts cells 4. Sensory function: Mechanoreceptors in P.L. regulate amount of masticatory occlusal forces. If high forces upon the periodontium → Stimulation of great numbers of mechanoreceptors → send inhibitory impulses passing via sensory nerves to stop masticatory forces. Factors affecting periodontal health in fixed prosthodontics: I. Axial crown contours Proximal contact Embrasure Facial & lingual contour Emergence profile II) Occlusal morphology I. Occlusal table dimension. Force magnitude, duration, frequency III) Crown Margin placement Extension (location/position) length Nature & shape, (sharp/dull/round/blunt/polished) Restoration material Shape ,thickness & adaptation of margins IV) Pontic design & material V) Bridge design I. Axial crown contours: A. Facial & lingual contours: ❑ The height of contour must be in harmony with adjacent natural teeth. Position of height of contour : The height of contour on the facial surface of posterior teeth usually occurs in the cervical third. The height of contour of lingual surface of mandibular posterior teeth is located in the middle one third  Overcontouring: Leads to accumulation of food debris and plaque and gingival inflammation. Under contouring: Leads to forced deflection of food and gingival recession. Emergence Profile The part of the axial contour that extends from the base of the gingival sulcus past the free margin of the gingiva. The emergence profile extends to the height of contour, producing a straight profile in the gingival third of the axial surface. Production of a straight profile should be a treatment objective in restoring a tooth, because it facilitates access for oral hygiene measures. B. Proximal contour:is very important to the periodontal health 1. Proximal contact: ▪ Proper contact prevents food stagnation between teeth & stabilize them in the denta arch. The contact must be more than a point ▪ Should not extend too much cervically → not to encroach on the gingival embrasure. ▪ Location of proximal contact (Contact position): OG: for posterior teeth, in the Occ.1/3, except for upper 6 & 7→ in M 1/3 BL: slightly facial to the middle of the posterior teeth, except for 1st. & 2nd. molars → centered facio-lingualy.  Contact dimension: Proper contact dimension → prevents food impaction + allows easy cleaning. Broad proximal contact (wide BL)narrow embrasure)→ blocks the embrasure + interferes with proper cleaning inter- proximally. Crowding papillae Trapping food debris → gingival inflammation + pressure on inter- dental papilla. Narrow contact (point contact) (wide embrasure)→ allows food impaction (Wedging of fibrous food) but the impacted food can be removed easily. III. Crown margin placement: Placement of Margins of Restorations Where does the gingival margin go? Supra gingivally. Sub gingivally. At the crest of the marginal gingiva.  Margins are always rough due to micro-irregularities inviting food debris & plaque accumulation → continuous irritation, decay, gingival inflammation & periodontal pocket. From a periodontal viewpoint both supragingival and equigingival margins are well tolerated. The greatest biologic risk occurs when placing margins subgingivally. 1. These margins are not as accessible as supragingival or equigingival margins for finishing procedures, and in addition, 2. if the margin is placed too far below the gingival tissue crest, it violates the gingival attachment apparatus. 3. The ideal intra-crevicular position for margins is 0.5 mm. beneath the gingival crest 4. If gingival recession, the F.L. & crown margin should be placed at CEJ. Clinical situations requiring sub-gingival finish line: 1. Esthetics. 2. Cervical erosion, caries, and old restoration extend sub- gingivally. 3. Root sensitivity. 4. Addition retention in case of short clinical crown OG height. 5. Proximal contact area extends to gingival crest.  Periodontists recommend that when determining where to place the restoration margins relative to the periodontal attachment, the patient’s existing sulcus depth be used as a guideline in assessing the biologic width requirement for the patient. 1. If the sulcus probes 1.5 mm or less, place the restoration margin 0.5 mm. below the gingival tissue crest. 2. If the sulcus probes more than 1.5 mm, place the margin one half the depth of the sulcus below the tissue crest. 2. Material of the crown margin: a. Porcelain : Highly glazed porcelain → the most biologically accepted material. Chemically inert & easily cleaned. b. Gold alloys : Highly compatible material after good finishing & polishing. Sub-gingival margins may be burnished on the die with a fine stone. No intra-oral finishing is done to avoid injury to the gingiva. c. Base metal alloys: Any rough areas or margins are smoothened with blue rubber wheels followed by white rubber wheels. d. Acrylic resin: A.R. margin is rough & contains excess monomer 3. Nature of the crown margin: Thin lancet margin was recommended for maximum adaptation to tooth surface, but it causes constant irritation & laceration to gingival tissues. Margins → rounded, smooth, blunt, dull & highly finished & polished. Rough, sharp, porous margins → bacteria & plaque → irritation to gingival tissues → gingivitis & periodontal breakdown. Fingertip examination of all restoration margins should be done carefully before insertion to ensure smooth, rounded, polished extensions for better gingival tissue tolerance. Sensitive fingertips are a great aid to biologic compatibility. 4. Shape, thickness & adaptation of margins: Successful margins should possess good marginal adaptation with a gap of less than 50umm. Types of defective margins: a. Over-extended margin. b. Under-extended margin. c. Thick margin. d. Open margin. Fit and adaptation of margins: Successful margins should possess a gap of 50-120 µm. Types of defective margins: a. Overextended b. Underextended c. Thick d. Open III) Questions Related to Pontic Concern two areas Materials Design Factors must be 1. Gingival Surface. considered: 2. Occlusal Surface. The effect of the 3. Labial, Buccal, and material itself Lingual Surfaces. 4. Proximal Surfaces The effect of the surface finish Both of them.  Pontics are classified according to contact to oral mucosa into: Mucosal Contact Non-Mucosal Contact Ridge Lap Sanitary (Hygienic) Modified Ridge Lap Modified Sanitary Ovate Pontic Conical Pontic.  2. Occlusal Surface ❑One Concept advocates the reduction of the occlusal dimensions. The reduction of the occlusal width ranging from one fifth to one third the buccolingual dimension is specified to control the force on the abutment teeth. ❑The Second Concept maintains normal occlusion width, -To provide a soft tissue protective mechanism during mastication. -To provide adequate occlusion with the opposing arch. ❑The Third Concept tends to minimize the significance of occlusal dimension. Recent research points out the importance of the proprioceptive mechanism in regulating the occlusal force regardless of the dimension of the opposing food tables.  4. Bridge Design Different Fixed Partial Denture Designs produce different magnitude of tipping force A)Fixed Fixed Bridge B)Fixed Supported Bridge C)Fixed Free (Cantilever Bridge)  IV. Occlusal Morphology: one should make every effort to direct occlusal forces in an axial direction to benefit from the greater tolerance of the periodontium to forces in this direction. Periodontium tolerates occlusal forces falling along the long axis of the tooth. Lateral or horizontal forces are ordinarily accommodated by bone resorption in areas of pressure and bone formation in areas of tension.  The effect of occlusal forces on periodontium is influenced by: 1. Direction of the applied force: The most favorable force → along the long axis of the tooth that transferred into tension in the periodontal ligament → bone deposition. The horizontal, lateral & torque forces → transferred into compression in the PL → bone resorption. 2. Duration of the applied force: Intermittent forces (mastication): The most favorable force → relaxation period → time for healing & repair. Continuous forces: very harmful to the periodontium. caused by para-functional activity → do not allow time for repair 3. Magnitude (Severity) of the applied force: Force within the physiological capacity of the periodontium → adaption by PL. → thickening + ↑ density of supporting bone. Force > capacity of the supporting tissues torque → pathological changes in the periodontium ''traumatic occlusion'' When the occlusal forces exceed the adaptive capacity of the periodontium tissue injury results. Periodontal injury caused by occlusal forces is called occlusal trauma.  Premature contact or cuspal interference lead to → stress concentration at a point → destruction in the periodontium & traumatic occlusion. Ex.(Premature contact, Para-functional habits ,improper orthodontics & PD. with occ. rest on teeth). Trauma from occlusion occur in three stages: Injury., Repair ( if condition is corrected). Change in morphology of periodontium (if condition is not corrected). Occlusal trauma is defined as an injury to the peridontium (periodontal ligament, alveolar bone, and cementum) as a result of excessive occlusal force. Occlusal trauma will clinically manifest itself : Increasing mobility and/or migration of the teeth. Persistent discomfort or tenderness. Pain to percussion or upon biting. Radiographic signs of the traumatic lesion may include The presence of a widened periodontal ligament space, Discontinuity of the lamina dura surrounding the tooth roots,Alveolar bone and/or root resorption. Trauma from occlusion does not cause gingivitis or periodontal pockets which means that they are caused by local irritation from plaque, bacteria, calculus and by food impaction. Primary and secondary occlusal trauma The tissue injury associated with occlusal trauma is often divided into two categories: primary and secondary. In primary occlusal trauma, a lesion results from application of excessive occlusal forces to a tooth or teeth with normal supporting structures: In secondary occlusal trauma, Pathologic lesion caused by normal force on diseased periodontium. I) Tooth Mobility: Mobility beyond the physiologic range is termed abnormal or pathologic. Increased mobility is caused by one or more of the following factors: 1. Occlusal trauma. 2. Trauma due to accident. 3. Periodontal involvement increased bone resorption leading to mobility. 4. Para-functional habits. Ex. Continuous forces with no time for repair. 5. Clinically detected by pressing the teeth between a hard object (e.g. mirror handle) & a finger. X-ray appears as widened periodontal ligament space.  Evaluation of tooth mobility (Miller Mobility Index) Grade 0: physiological mobility Grade 1: increased mobility but less than 1 mm in total mobility 2mm buccolingually &/or vertical tooth mobility Splinting: is to secure the injured part of the body to decrease further damage or injury, and to make the individual more comfortable. The ligating, tying, or joining two or more teeth for the purpose of stabilization. Functions of splinting: 1. Stop mobility or arrest its increase. CAUSE IT Redistribute occlusal forces over large no of teeth. 2. Protect loose teeth from injury during FUNCTION OR MASTICATION. 3. Prevent natural teeth from migrating and super-erupting. 4. Centre of rotation is transferred to the middle third. Indications: 1. To stabilize periodontally involved and mobile teeth. 2. Bruxism. 3. To Stabilize Teeth After Trauma. 4. To retain orthodontically repositioned teeth. Prevention of tipping, drifting and supereruption of unopposed teeth. The use of healthier teeth results in a new increase in crown- root ratio and a net decrease in force to the individual tooth, especially in a horizontal direction. (Guillermo et al 2002) Factors affecting the number of teeth required to stabilize a loose tooth: 1. Depends on the grade and direction of mobility. 2. Amount of remaining bone. 3. Position of the tooth in the arch. 4. Whether it is used as an abutment. Methods of splinting: 1. Temporary, reversible and provisional splint. Short term 6-8weeks Temporary splinting may or may not be followed with permanent splinting. Temporary splinting is accomplished with the composite material alone or in combination with extra and intra coronal wires or screen meshes. Composite filling splints Composite and wire splint Resin fiber reinforcement splints Ligature wire, A-splint or circumferential wires. (Rarely used)) 3 4. Provisional splinting with full-coverage acrylics ( Commonly used ) Removable appliances.. Acrylic bite-guards or occlusal splint: Orthodontic retainer. b. Permanent splint: Fixed partial denture with rigid connectors Resin bonded retainers Pinledge retainers -II) Tooth preparation and crown configuration in periodontally compromised teeth:  Patients Healthy Periodontally periodontium compromised Treat the condition Preserve the condition Arrest its progress Restoration that will not insult Establish a regimen of strict oral hygiene Use a restoration to preserve heathy the attachment apparatus attachment apparatus of abutment tooth  EXAMINATION Visual examination: evaluation of color consistency, texture and shape of gingiva Proping: 6 areas around the tooth pocket depth, bleeding on probing Furcation involvement: Mobility: Xray: alveolar crest resorption Integrity of thickness of lamina dura Horizontal bone loss Vertical bone loss Widening of periodontal ligament space C/R ratio  Sequence of Treatment of periodontally compromised patients: 1. Control of dental plaque by establishing adequate oral hygiene measures. 2. Scaling and Root planning 3. Correction of any defective restorations. 4. Removal of compromised teeth. 5. Occlusal adjustment. 6. Splinting. 7. Surgical therapy if needed. 8. Treatment of furcation involvement. 9. Temporary restorations. 10. Final restorations after perio ttt by 4-6 weeks.  Treatment plan for periodontally compromised dentition. Preprosthetic Prosthetic phase phase Initial therapy Surgical therapy FURCATION INVOLVEMENTS Glickman’s classification Grade I → < 3mm apical to CEJ. Grade II → >3mm. but no total horizontal involvement of furcation. Grade III → Horizontal through & through lesion that is occluded by gingiva Grade IV → Horizontal through & through lesion that is not occluded by the gingiva  PREPARATIONS FOR PERIODONTALLY COMPROMISED TEETH Restoration of molars with furcation involvement Early Grade I & II → fluted complete crown preparation with cast restoration. Deep Grade II, III & early Grade IV → Root amputation, hemisectioning then post & core & complete crown. Grade IV with advanced vertical loss → Poor restorative prognosis consider retaining one root to support an overdenture.  Prosthodontic considerations after periodontal treatment 1-Margin placement: a- Supragingival margin placement: Whenever possible, margins are parepared supragingivally on the enamel of the anatomic crown.  MARGIN PLACEMENT: On enamel, away from the gingival sulcus. Extends apically to cover root surface that may have been affected by caries or erosion.  2- Preparation of finish line A shoulder is a poor choice when the margin must be placed on the root surface because of the constricted, smaller diameter of the root. ▪ 1.0mm wide Shoulder will lead to : 1- Possible pulpal encroachment. 2-Weakening the natural structural durability of the tooth.. 3-The shoulder has a greater potential for concentrating stresses that could ultimately lead to fracture of the tooth. A chamfer finish line on the facial surface in this apical position will result in approximately the same depth of axial reduction as would a shoulder at the usual level. A- Knife edge prep. Keep axial walls safely from the pulp. B- Shoulders placed on root surfaces compromise the pulp  A metal-ceramic crown fabricated in such circumstances should have a wide metal gingival collar to blend the root contour with that required for a ceramic veneer of adequate thickness.  3- Furcation flutes: A Sometimes, the finish line should be extended too apically till it approaches the furcation area where the common root trunk divides into 2 or 3 roots. There will be intersection of the finish line with the vertical flutes and concavities which is normally present in the root trunk (A). B The axial surface of the restoration occlusal to the gingival finish line must also have the same vertical flutes or concavities until it meets the facial grooves in the occlusal third of the facial surface (B).  Any horizontal ridge in the facial or lingual surface of the tooth that intersect with the vertical flutes or concavities result in plaque retaining areas.  Prosthodontic considerations after periodontal treatment 4- Wound Healing considerations: The time elapsed after completion of periodontal treatment is crucial when intracrevicular margins are anticipated. Gingival margins after surgery commonly migrate coronally, whereas they tend to recede after scaling and root planning. Margins prematurely placed intracrevicularly in the second situation often become exposed as healing progresses, and the result may be unesthetic.so we must leave suffient time after surgry before prosthodontic tttt 2 months  Prosthodontic considerations after periodontal treatment 6- Attached Gingiva: The avoidance of traumatic gingival recession usually depends on a zone of thick keratinized gingiva 4 to 5 mm in width, of which 2 to 3 mm is attached.  Despite tissue keratinization, if the probe is seen through the free gingival margin, the ability to resist trauma is doubtful. The surgical placement of a thicker, free autogenous gingival graft is indicated before the final tooth preparation of intracrevicular margins.  Prosthodontic considerations after periodontal treatment 7- Restoration of Endodontically Treated Teeth: -Posts are recommended to be extended to one- half the length of the root remaining in bone. - In the periodontal patient these posts often extend into the apical one-third of the root. -This needs tapered posts instead of parallel posts to minimize thinning of dentin at the post apex, especially in teeth with cone-shaped roots.  Screw-type posts, while more retentive than cemented posts, produce greater stress on the root. They are not used near the apex, since minute dentin fractures are likely to be present from the root canal instrumentation. Pin-retained amalgams alone or in combination with posts of modified lengths have been used if the attachment loss extends the posts too near to the root apices.  Prosthodontic considerations after periodontal treatment 8- Gingival Retraction and Impression: All retraction methods induce transient trauma to the junctional epithelium and connective tissue of the gingival sulcus.  A- Retraction Cord: If the retraction cord is used carelessly with inadequate attached gingiva, injury to the gingival fibers occurs. This can allow impression material to be forced into the gingival connective tissue and bone, producing a foreign body reaction. This can manifest as a localized periodontal abscess or a diffuse cellulitis. Radiographs will reveal the radiopaque material and are a diagnostic aid when impression material is suspected as a cause of inflammation.  DISPLACEMENT PASTES Expasyl is an AlCl3-containing paste is injected into the dried sulcus with a special delivery gun. Advantages of this system include good hemostasis with less discomfort than with tradiHowever, less tissue displacement is achieved than with cord, which may make subsequent laboratory steps such as die trimming more problematic. tional cord. ❑. The material is dispensed from a syringe directly into the sulcus.  EXPANDING POLYMERIC FOAM Expanding polymeric foam provides tissue displacement with minimal discomfort or gingival trauma. A, Magic FoamCord polyvinyl siloxane tissue displacement system.  EXPANDING POLYMERIC FOAM ❑ The patient closes on the cotton ❑ Maxillary incisor prepared for an ❑ The expanding polymeric foam is roll, maintaining pressure for 5 all-ceramic crown. Hemorrhage injected around the preparation and minutes. Tissue has been displaced control with ferric sulfate can be condensed with a special hollow cotton from the preparation margins used if bleeding is noted. roll (Roeko Comprecap Compression before the impression material is Caps). injected.  b. Electrosurgery: -The use of modern units by skilled dentists results in cellular healing comparable to a scalpel cut. - Controlled depth cutting electrode tips avoid bone trauma but injure the gingival fibers if the tip is not angled properly in the sulcus. 9- Temporary and Provisional Crowns: Provisional restorations can provide several functions: 1- Improve esthetics. 2-It can restore the occlusal scheme to be incorporated into any definitive prostheses. 3-After wearing a provisional restoration, patients should be reevaluated to determine if treatment should proceed to a definitive restoration. 4-Only after the provisional restoration has been worn by the patient, the design and occlusal form can be evaluated. This evaluation should be made before deciding to proceed with the definitive restoration. Prosthodontic considerations after periodontal treatment 10. Crown Contours a. Facial and Lingual Sulcular Contours: -On the marginal or radicular surfaces, the enamel contours in the sulcular region flare from the vertical axis of the gingiva to support the gingiva (A). A -The intracrevicular contours of an artificial crown should be as close to the original enamel contour as possible (B). -Wagman 1980 has estimated this angle of enamel flare from the CEJ to be approximately 22.5 degrees from the vertical B axis of the gingival housing.  As the gingival margin progresses more apically, the sulcus narrows, and the intracrevicular contours of the tooth become the flat contours of the root rather than the convex surface of the anatomic crown. In this situation, the intracrevicular contours of the artificial crown do not mimic the root but depend on the adjacent gingival morphology. When intracrevicular margins are adjacent to thin gingiva on the root, the sulcular contours of the artificial crown should be flat, mimicking the shape of the root, to prevent overcontouring.  When intracrevicular margins are adjacent to thick gingiva on the root, the sulcular contours of the artificial crown should incorporate the average A enamel bulge angle to support the thick gingiva (B). B  b. Proximal Contours: Proximal root surface concavities on posterior teeth can be reduced in the contours of the final restoration if more tooth structure is reduced over the buccal and lingual prominences than over the concavities during preparation.  The interdental brush was A demonstrated as an effective proximal cleaning device in altered periodontal environments when root concavities were prevalent. The interdental brush is not effective B in deplaquing the tooth surface at the gingival margin if it fits too loosely in a large embrasure (A). Proximal overcontouring is indicated to allow snug passage of the brush through the interdental embrasure (B).  Prosthodontic considerations after periodontal treatment 11- Occlusal surface: -In an effort to direct the occlusal forces along the long axis of the tooth, prostheses should be designed with a narrower occlusal table and cusp fossa occlusal contacts and the steepness of cuspal inclines reduced. - -Even contacts should be established anteriorly as well as posteriorly, with freedom in centric occlusion. -Overbite and overjet should be minimal. -The occlusal contacts should be monitored regularly and adjusted accordingly during maintenance.  Other treatments to consider in occlusal equilibration are: -Shortening extruded teeth. -Improving the alignment of rotated, malposed or tilted teeth. -Correcting discrepancies in marginal ridge relationships. - The anatomy of the occlusal surface should provide well- formed marginal ridges and occlusal sluiceways to prevent interproximal food impaction.  Prosthodontic considerations after periodontal treatment 12-Cementation: All intracrevicular margins are checked carefully after cementation for excess cement. The cement material is tolerated by the gingiva, but retains plaque as an overhanging margin regardless of the margins. These cement excesses are often subgingival, so the material is unnoticed and slowly dissolves. THANK YOU