Fixed Prosthodontics Lecture No:9 PDF

Fixed Prosthodontics Lecture No:9 Fluid (moisture) control, isolation & soft tissue management in FPD Lecturer: Dr.Lana Bahram Khidher BDS,Ph.D in Prosthodontic INTRODUCTION Control of fluids and appropriate disp...

Fixed Prosthodontics Lecture No:9 Fluid (moisture) control, isolation & soft tissue management in FPD Lecturer: Dr.Lana Bahram Khidher BDS,Ph.D in Prosthodontic INTRODUCTION Control of fluids and appropriate displacement of the gingiva are essential during tooth preparation to obtain accurate impressions, and for cementation. FLUID SOURCES IN THE ORAL CAVITY: Saliva(pair of parotid &submandibular and sublingual glands) Inflamed gingival tissues/ Iatrogenic soft tissue damage (Gingival bleeding during tooth preparation) Water / dental materials (Rotary instruments, triplex syringe, etchants, irrigant solutions Gingival crevicular fluid (Sulcular fluid). Fluid control objectives (( WHY SHOULD ISOLATE THE OPERATIVE SITE?)) 1. To obtain a dry clean operating field 2. For easy access and visibility 3. To improve the properties of dental materials 4. To protect the patient and the operator 5. To improve the operating efficiency Methods The methods employed may perform the task of fluid control, isolation and retraction of oral tissues, singly or in combination. Depending on the location of the preparations in the dental arch, a number of techniques can create fluid control & the necessary dry field of operation. Rubber Dam It is used to isolate the tooth during restorative procedures. Some authors indicate its use during preparation, impression and cementation of indirect restorations. When used with elastomeric impression materials, it should be lubricated and clamp removed. When all margins are supra-gingival, moisture control with a rubber dam is probably the most effective method. In most instances, however, a rubber dam alone cannot be used, so a Multiple Isolation Techniques should be performed to achieve optimal saliva control. Cotton roll Simplest method of fluid control and isolation. Used during impression and cementation procedures. Absorbent cotton rolls must be placed at the source of the saliva, the muco-buccal fold or in the sublingual area, In the maxillary arch, placing a single cotton roll in the vestibule immediately buccal. When a mandibular impression is made, placement of additional cotton rolls to block off the sublingual and submandibular salivary ducts is usually necessary. Saliva ejector (low vacuum suction) Used for fluid removal during impression and cementation procedures. May be used during tooth preparations in maxillary arch by placing it in the corner of the mouth opposite the side being prepared, with the patient’s head turned towards that side. It is not as effective as high vacuum suction. Can be used without any assistance. Antisialogogues When saliva control is difficult a medication with anti-sialagogic action (drugs that inhibit parasympathetic innervation and thereby reduce secretions, including saliva) may be considered. This is especially beneficial during impression making. Dry mouth is a side effect of certain anticholinergics. Anticholinergic drugs – atropine, dicyclomine and propantheline may be used. They are given 1 h prior to commencement of dental procedure. They are contraindicated in patients having hypersensitivity to the drug, asthma, obstructive conditions of the gastrointestinal tract and congestive cardiac failure. It should be prescribed with caution in older adults and should not be administered to any patient with heart disease. They are also contraindicated in individuals with glaucoma because they can cause permanent blindness. Clonidine, an antihypertensive drug may also be used. It is safer than anticholinergics but should be used with caution with other anti-hypertensives. It can cause drowsiness which may not be desirable. Local anesthetic materials In addition to pain control, local anesthetics also reduce salivary flow during impression making. They act by blocking nerve impulses from the periodontal ligament that regulate salivary flow Definition: The deflection of the marginal gingiva away from a tooth Also called gingival retraction or tissue dilation. It is essential that the gingiva is in a healthy state before the tooth preparation. Indications Objectives 1. To provide adequate reproduction of finish lines. To expose the prepared finish line, and evaluate the depth and 2. To accurately duplicate sub gingival margins. uniformity of it without laceration of soft tissues. 3. To provide the best possible condition for the To control the gingival crevicular fluid. impression material , fluid control. Provides access for the impression materials to record accurately 4. To fabricate accurate restorations thereby the finished margins and a part of the unprepared tooth beyond preventing periodontal disease. the finish lines. Helps to obtain accurate marginal fit which will reduce the marginal leakage and subsequent deterioration of the tooth.  Gingival SULCUS (Crevice) A shallow groove around the tooth bounded on one side by the surface of the tooth and on the other by the epithelial lining of the free margin of the gingiva. It is “V” shaped with its base at the most coronal level of the epithelial attachment to the tooth root. Biological Width Biologic width is defined as the dimension of the soft tissue, which is attached to the portion of the tooth coronal to the crest of alveolar bone. It acts as a barrier and prevents penetration of microorganisms into the periodontium. Gingival retraction techniques: 1) Mechanical. (plain Retraction cord ,Retraction Crown, Copper band or tube , Anatomic compression caps, Matrices and wedges, Rubber dam ) 2) Chemo mechanical (combination of mechanical and chemical) a) Impregnated Retraction cord ,with one of following; aluminum sulfate ferric sulfate aluminum chloride epinephrine b) Displacement polymer & paste(Cordless technique) 3) Radical or surgical means or technique (Electrosurgical,Laser). zinc chloride Mechanical Method of Retraction This method physically displaces the gingiva. Generally in this technique, we apply pressure on the gingiva through gingival sulcus. This mechanical pressure, after certain period of time, physically push the gingiva away from the finishing line. It might be done by the construction of temporary crown with slightly long margin leaving it for 24 hours, or by using rubber clamp, or by using plan retraction cord( free of medicament )….etc. The most common way by using retraction cord. Retraction cord is a special cord made of cotton comes either with or without medicament (vasoconstrictor). Classification of retraction cords 1. According to chemical treatment a) Plain….cord without any medicament. b)Impregnated…..cord impregnated with hemostatic agent. 2. According to configuration: Twisted Knitted Braided Advantages of Knitted cord over other; 1) Afford greater inter-thread space than braided cord. 2) Form an interlocking chain of thousands of tiny loops, making it: easy to pack below the gingival margin stays put when packed into place. 3) Compresses upon packing, then expands for tissue displacement. 3. According to thickness (diameter) According to its size, we have different thickness of retraction cord ( color coded thickness); Black - 000 Yellow – 00 Both are recommended for anterior teeth with minimal crevicular space. Also can be used as a primary cord for the double cord technique. Purple - 0 Blue – 1 Both are recommended for bicuspids. Also #0 is used as the primary cord for the double cord technique, while , #1 cord is recommended to be used as the secondary cord Green - 2 Red – 3 Both sizes are is used for molars where tissue friability permits Some textbook divide retraction cord into three main size; SMALL- involve (#000 &# 00) to be used in anterior teeth, where thin firmly tissue is present MEDIUM- involve (#0, #1 & #2) to be used where greater bulk is encountered e.g. posterior teeth LARGE- involve size (#3) should be used with caution as can produce soft tissue trauma. Instrument Instrument used for packing the cord is called ‘Fischer’s cord packer’, It should be thin enough to be placed in the gingival sulcus without damaging the tissues, and the angle of the instrument should allow packing of the cord all around the tooth.  Displacement techniques Two methods may be employed: 1. Single-cord technique: One cord is placed in the sulcus and the impression is made immediately following retraction after removing the cord. is the most commonly used method. Indicated for making impression of one to three prepared teeth with healthy gingiva tissues. 2. Double-cord technique: Two cords are used; one thin cord is first packed deep into the sulcus and left there during impression making to provide haemostasis. The second cord is placed over the first cord to provide retraction, and is removed immediately prior to impression making. It is indicated when making impressions of multiple prepared teeth and when tissue health is slightly compromised with more than normal bleeding anticipated.  Gingival retraction paste (Cordless technique): This is a recent development where retraction is achieved using only chemicals. This consists of an aluminium chloride–containing paste (Expasyl) , which is injected into the sulcus prior to impression making.The paste is left in the sulcus for 3–4 min to achieve the desired retraction. It is washed off and impression is made. Advantage Achieves good haemostasis with less trauma.  Surgical technique (radial or surgical means) ROTARY GINGIVAL CURETTAGE (GINGETTAGE) : Rotary curettage is a troughing technique. Epithelial tissue in the sulcus is removed by a rotary instrument while finish line is being created. A supragingival finish line is first created to complete the tooth preparation. Electrosurgery: In this technique, an electro-surgical unit could be used to remove the gingival tissue from the area of the finishing line with the advantage of controlling the post-surgical hemorrhage. However, electrosurgery is contraindicated when there is gingival inflammation or periodontal disease. In this case, gingivectomy could be performed. There is the potential for gingival tissue recession after treatment Soft Tissue Laser: Soft tissue lasers have been introduced into dentistry and can provide an excellent adjunct for tissue management before impression making For gingival retraction, Nd- YAG lasers types are used. Advantages of laser: 1. Certain laser dentistry procedures do not require anesthesia. 2. Laser procedures minimize bleeding because the high-energy light beam aids in the clotting (coagulation) of exposed blood vessels, thus inhibiting blood loss. 3. Bacterial infections are minimized because the high-energy beam sterilizes the area being worked on. 4. Damage to surrounding tissue is minimized. 5. Wounds heal faster and tissues can be regenerated. Disadvantages: 1. Slow technique. 2. Expensive.