Obturation First Lecture 2024 PDF

Obturation of The Root Canal System By Mahmoud Ramadan Abo ElSeoud Lecturer of Endodontics Faculty of Dentistry Alexandria University Remember: The main cause of pulpal and periapical disease is BACTERIA. Factors affecting outcome of primary root canal treatment (2 factors related to obturation...

Obturation of The Root Canal System By Mahmoud Ramadan Abo ElSeoud Lecturer of Endodontics Faculty of Dentistry Alexandria University Remember: The main cause of pulpal and periapical disease is BACTERIA. Factors affecting outcome of primary root canal treatment (2 factors related to obturation) 1. Absence of preoperative radiolucent lesion. 2. Dense filling with no voids. 3. Filling within 0-2 mm of the radiographic apex. 4. Satisfactory coronal restoration. Why to obturate the root canal after biomechanical preparation ? 1. Studies indicate that root canal systems cannot be completely cleaned and disinfected (bacteria free canals). 2. Since the primary etiology of pulpal and periradicular pathosis is bacterial.  Therefore , obturation of the radicular space is necessary to (Objectives of obturation): 1. Entomb the remaining irritants in the canal. 2. Seal the apex from the periapical tissue fluids (prevents apical leakage). 3. Obturation also reduces coronal leakage (prevents coronal leakage) ( Achieved with adequate coronal restoration) .  Simply, obturation serves to prevent the traffic of fluids from the periradicular tissues or saliva into the canal as well as of bacteria and their products from the canal to the periradicular tissues.  Obturation main aim is to prevent leakage and reinfection of the cleaned and disinfected root canal system. Obturation should seal the root canal apically, laterally and coronally It should be noted that effective coronal seal maintaining an (permanent restoration) is considered essential for long term successful root canal treatment. Root canal obturation materials 1.Sealer. 2.Core material. Root Canal Sealers  Functions of root canal sealers: 1. Root canal sealers are necessary to seal the space between the dentinal wall and the obturating core interface. 2. Sealers also fill voids and irregularities in the root canal, lateral and accessory canals. 3. Fill the spaces between gutta-percha points used in lateral condensation. 4. Serve as lubricants during the obturation process. • Grossman outlined the properties of an ideal sealer. • At present no sealer satisfies all the criteria. Common features for all types of sealers:  Sealers are biocompatible and well tolerated by the periradicular tissues.  All sealers exhibit toxicity when freshly mixed; however, their toxicity is greatly reduced on setting.  Sealers are resorbable when exposed to tissues and tissue fluids.  Tissue healing and repair generally appear unaffected by most sealers, provided there are no adverse breakdown products of the sealer over time. Types of Root Canal Sealers The most popular sealers are: 1. Zinc oxide–eugenol formulations. 2. Calcium hydroxide sealers. 3. Glass ionomer sealers. 4. Resin based (epoxy resin or methacrylate resin) sealers. 5. Calcium silicate–based sealers. Zinc Oxide and Eugenol  Zinc oxide–eugenol sealers have a history of successful use over an extended period of time.  Zinc oxide–eugenol sealers will resorb if extruded into the periradicular tissues.  Features of ZOE sealers:  Slow setting time.  Shrinkage on setting.  Solubility.  Can stain tooth structure.  An advantage to this sealer group is antimicrobial activity. Example: Pulp Canal Sealer Calcium Hydroxide Sealers  Calcium hydroxide sealers were developed for therapeutic activity (antimicrobial, mineralization potential) .  It was thought that these sealers would exhibit antimicrobial activity and have osteogenic–cementogenic potential.  Unfortunately, these actions have not been demonstrated.  Solubility is required for release of calcium hydroxide and sustained activity which is inconsistent with the purpose of a sealer. Examples:  Calciobiotic root canal sealer .  Apexit and Apexit Plus . Glass Ionomer Sealers Glass ionomers have been advocated for use in obturation because of their dentin-bonding properties. A disadvantage of glass ionomers is their removal if retreatment is required.  This sealer has minimal antimicrobial activity. Example: Ketac-Endo. Resin Sealers Resin sealers have a long history of use , they provide adhesion, and do not contain eugenol. There are two major categories: Epoxy resin–based. Methacrylate resin–based sealers. Epoxy Resin Sealers AH-26 (DENTSPLY) is a slow setting epoxy resin that was found to release formaldehyde when setting. AH Plus (DENTSPLY ) (Gold Standard) is a modified formulation of AH-26 in which formaldehyde is not released. The sealing abilities of AH-26 and AH Plus appear comparable.  AH Plus is an epoxy resin–amine based system that comes in two tubes.  It exhibits a working time of approximately 4 hours. AH Plus sealer is a resin formulation. (Courtesy DENTSPLY DeTrey, Konstanz, Germany.) AH Plus sealer achieves high bond strength to both dentin (2.06 MPa) and gutta-percha (2.93 MPa). The adhesiveness of AH Plus to root dentine is related to covalent bonds between epoxide rings and the exposed amino groups in the collagen network of dentin. Methacrylate Resin Sealers  Four generations of methacrylate resin–based root canal sealers have been marketed for commercial use.  The bondable root canal sealers has been aggressively promoted with the highly desirable property of creating monoblocks within the root canal space ( similar to bonding composite to dentin).  It was suggested that monoblock obturation improves the seal and fracture resistance of the filled canals.  The formed bond was not durable and long term failure was noted. Silicone Sealers  Example: RoekoSeal is a polydimethylsiloxane that has been reported to expand slightly on setting.  Example: GuttaFlow and GuttaFlow2 are cold flowable matrices that are triturated.  They consist of gutta-percha in particulate form (less than 30 μm) added to RoekoSeal.  The material is provided in capsules for trituration.  The technique involves injection of the material into the canal, followed by placement of a single master cone.  The material provides a working time of 15 minutes and it cures in 25 to 30 minutes.  The material fills canal irregularities with consistency and is biocompatible, but the setting time is inconsistent and may be delayed by final irrigation with sodium hypochlorite. GuttaFlow trituration capsule and injection syringe (Coltène/ Whaledent). Calcium Silicate Sealers  A new category of root canal sealers based on mineral trioxide aggregate (MTA) has recently been commercially available.  These sealers are based on tricalcium silicate, a hydraulic (water setting) powder used for various surgical and vital pulp therapy treatments. These sealers exhibit Bioactivity (induce hydroxyapatite formation) (therefore called Bioceramics) Ther are also hydrophilic (sets in the presence of moisture) .  Tricalcium silicate cements/sealers set by reaction with water and form a highly alkaline (pH of about 12) mixture consisting of a rigid matrix of calcium silicate hydrates and calcium hydroxide.  When tricalcium silicate cement sets, the dimensional change is less than 0.1% expansion, which helps with creating a barrier, and is especially important for obturation. Examples of tricalcium silicate sealers 1. Endosequence BC sealer. 2. Ceraseal. Premixed ready to use calcium silicate sealers Medicated Sealers  Sealers containing paraformaldehyde (e.g: Sargenti paste, N2, RC2B) are strongly contraindicated in endodontic treatment.  These sealers are not approved by the U.S. Food and Drug Administration and are unacceptable under any circumstances in clinical treatment because of the severe and permanent toxic effects on periradicular tissues. The toxic in vivo effects of these materials on the pulp and periapical tissues have been demonstrated over time. Overextension has resulted in osteomyelitis and paresthesia. Core Materials The most common method of obturation involves gutta-percha as a core material.  Regardless of the obturating technique, emphasis should be placed on the process of shaping and cleaning the canal. The properties of an ideal obturation material have been outlined by Grossman. Core obturating materials may be classified into: 1. Solids ( Silver cones used in the past). 2. Semisolid materials ( GP ) ( The most common material nowadays). 3. Pastes ( not used any more). Silver Cones ( not used nowadays) Jasper introduced cones made of silver, which he claimed produced the same success rate as gutta-percha and were easier to use. Disadvantages of silver cones: 1. When silver points contact tissue fluids or saliva, they corrode. The corrosion products have been found to be cytotoxic and produce pathosis or impede periapical healing. 2. Silver cones are rigid so can be easily placed to length.  This resulted in clinician often failing to properly clean and shape the canal before obturation (canals may be instrumented to file # 15 or # 20 without any coronal flaring). Silver cones are advocated for ease of placement and length control. A, Radiograph of a facial maxillary right central incisor obturated with a silver cone. B, Tissue discoloration indicating corrosion and leakage. C, Lingual view indicates coronal leakage. D, Corroded silver cone removed from the tooth. E, Post-treatment radiograph of the tooth Gutta-Percha Gutta-Percha  Gutta-percha is the most popular core material used for obturation.  Major advantages of gutta-percha are its: 1. Plasticity, ease of manipulation. 2. Minimal toxicity. 3. Radiopacity. 4. Ease of removal with heat or solvents.  Disadvantages include: 1. Lack of adhesion to dentin. 2. When heated, shrinkage upon cooling.  Gutta-percha cones consist of approximately: 1. 20% guttapercha. 2. 65% zinc oxide (antibacterial activity). 3. 10% radiopacifiers. 4. 5% plasticizers ( wax or resin). Rubber like material obtained from trees growing in Asia (Indonesia and Malaysia).  Since gutta-percha comes from trees, so its original color is white.  By the addition of dyes, its color usually changes to pink to simulate the color of the pulp ( the tissue that it replace).  Can be stained to any color by the addition of different dyes. Properties of gutta-percha:  Gutta-percha is the trans-isomer of polyisoprene (rubber) and exists in two crystalline forms (α and β).  In the unheated β phase, the material is a solid mass that is compactable.  When heated, the material changes to the α phase and becomes pliable and tacky and can be made to flow when pressure is applied.  A disadvantage to the α phase is that the material shrinks on setting. Gutta-percha can be made to flow if it is modified by either heat or solvents such as chloroform. This permits adaptation to the irregularities of the canal walls.  Gutta-percha cones are available in standardized (numbers) and nonstandardized (letters) sizes .  The nonstandard nomenclature refers to the dimensions of the tip and body. For example: A fine-medium cone has a fine tip with a medium body. Nonstandard guttapercha cones: extra fine, fine fine, fine, medium fine, fine medium, medium, large, and extra large. Standardized cones are designed to match the taper of stainless steel ( 2%) and nickel-titanium instruments ( 4%,6%). Standard gutta-percha cone sizes #15 to #40.  For example: A size 40, 0.02 taper cone has a tip of 0.4 mm and a taper of 0.02 mm per millimeter (2% Taper similar to size 40 file). Size #30 2 % taper file and standard gutta-percha point. Although gutta-percha points cannot be heat sterilized, gutta-percha points can be sterilized by placing in 5.25% NaOCl for one minute followed by 96% ethyl alcohol. WHEN TO OBTURATE THE CANAL 1. The root canal is ready to be filled when the canal is cleaned and shaped to an optimum size. 2. The tooth should be comfortable. 3. Dry canals may be obtained with absorbent points except in cases of apical periodontitis or apical cyst, in which “weeping” into the canal persists. 4. The smear layer (organic and inorganic components) lining the canal walls should also be removed. EXTENSION OF THE ROOT CANAL FILLING The anatomic limits of the pulp space are the cementodentinal junction apically, and the pulp chamber coronally.  Debate persists, however, as to the ideal apical limit of the root canal filling.  Canals filled to the apical CDJ are filled to the anatomic limit of the canal.  Beyond this point, the periodontal structures begin. Ideal termination of canal preparation and obturation. A, Apical constriction at cementodentinal junction marks end of root canal. From this point to anatomic apex (0.5 to 0.7 mm), tissue is periodontal. B, Photomicrograph of periapex. Small arrows at cementodentinal junction. Large arrow (bottom) at denticle inclusion  The CDJ junction is an average of about 0.5 to 0.7 mm from the external surface of the apical foramen, as clearly demonstrated by Kuttler, and is the major factor in limiting filling material to the canal. Therefore, filling to the radiographic end of the root is actually overfilling since the apical flare of the foramen is filled with periodontal tissue. Histologic section of a root apex, demonstrating anatomy of the classic foramen and constriction. Histologic section demonstrating the foramen exiting short of the root apex.