Components of The Root Canal System PDF

Components of The Root Canal System, Root Canal Anatomy & Objectives of Access Cavity Dr. Mohammed Basabrain Main Points Introduction (Prerequisites for endodontic treatment) Components of the root canal system Root Canal Anatomy Access Cavity  Introduct...

Components of The Root Canal System, Root Canal Anatomy & Objectives of Access Cavity Dr. Mohammed Basabrain Main Points Introduction (Prerequisites for endodontic treatment) Components of the root canal system Root Canal Anatomy Access Cavity  Introduction (Prerequisites for endodontic treatment) A thorough knowledge of tooth morphology Careful interpretation of angled radiographs Adequate access to and exploration of the tooth’s interior Main Points Introduction (Prerequisites for endodontic treatment) Components of the root canal system Root Canal Anatomy Access Cavity Components of the root canal system Dental pulp outline and composition Pulp chamber o Pulp horns Root canals o Canal orifices o Root canals o Accessory canals o Apical foramina  Components of the root canal system Dental pulp outline and composition o The root canal system housed by dentin where the dental pulp is located o The outline of this system corresponds to the external contour of the tooth o However, factors such as physiologic aging, pathosis, and occlusion may modify its dimensions by producing secondary and tertiary dentin and cementum o Dental pulp is a vascularized, innervated, unmineralized connective tissue Components of the root canal system Pulp chamber o Pulp horns The pulp chamber is the defined space lying in the center of the tooth Pulp horns are the extensions of the pulp chamber that curl up toward the cusps  Components of the root canal system Root canals Canal orifices are the opening which o Canal orifices leads from the pulp chamber into a root canal o Root canals A root canal is the naturally occurring anatomic space within the root of a tooth A root canal begins as a funnel-shaped canal orifice generally at or just apical to the cervical line It ends at the apical foramen, which opens onto the root surface at or within 3 mm from the center of the root apex the American Association of Endodontists  Components of the root canal system o Root canals A root with a tapering canal and a single foramen is the exception rather than the rule Sometimes, it has multiple foramina, additional canals, fins, deltas, ?? intercanal connections, loops, ‘C-shaped’ canals, and accessory canals. Loop5 Delta  Components of the root canal system o Root canals Types of Root canal system (Vertucci’s classification) The only tooth that showed all eight possible configurations was the maxillary second premolar Components of the root canal system o Root canals The pulp canal system is complex, and canals may branch, divide, and rejoin Consequently, the practitioner must treat each tooth, assuming that complex anatomy occurs often enough to be considered normal. Components of the root canal system Root canals Specific types of canal morphology appear to occur in different racial groups African American → higher number of extra canals in mandibular premolars than Caucasians. Asians have a higher → mandibular 2ed molars with single-rooted & C-shaped canals  Components of the root canal system Root canals o Accessory canals o Furcation canals accessory & lateral canals Lateral canals are channels that pass from the root pulp laterally through dentin to the periodontal tissue o Apical deltas Essentially it is just a very complex form of a lateral canal where one main canal branches in many apical exits Components of the root canal system Accessory canals Accessory canals are minute canals extend in a horizontal, vertical, or lateral direction from the pulp to the periodontium 74% of cases → apical third of the root 11% in the middle third 15% in the cervical third Accessory canals contain connective tissue They are formed by the entrapment of periodontal vessels in Hertwig’s epithelial root sheath during calcification Pathologically, they are significant because they serve as avenues for the passage of irritants, primarily from the pulp to the periodontium  Components of the root canal system Root canals o Apical foramina The apical foramen is the opening at the apex of the root of a tooth, through which the nerve and blood vessels that supply the dental pulp pass. Apical constriction (Minor apical diameter) Apical Foramen (Major apical diameter) The apical constriction (AC) The cementodentinal junction (CDJ) The apical Foramen (AF)  Components of the root canal system o Root canals Apical foramina Apical constriction (Minor apical diameter) It is usually 0.5 -1 mm short of apical foramen. Components of the root canal system o Root canals Apical foramina Apical Foramen (Major apical diameter) It is a rounded edge, like a funnel or crater, that differentiates the termination of the cemental canal from the exterior surface of the root. The apical foramen deviates from the apex in 50-98% of the teeth. This deviation averages 0.3 to 0.6 mm but could be as much as 3 mm. Main Points Introduction (Prerequisites for endodontic treatment) Components of the root canal system Root Canal Anatomy Access Cavity  Root Canal Anatomy Types of roots Mature (Straight) Mature (Curved) ▪ Slightly curved ▪ Severely curved ▪ Dilacerated ▪ Bayonet (S-SHAPE) Immature (Strait or curved) ▪ Tubular ▪ Blunder buss Main Points Introduction (Prerequisites for endodontic treatment) Components of the root canal system Root Canal Anatomy Access Cavity  Access Cavity Objectives Guidelines Important clues to the location of orifices and to the type of canal system Principles of Endodontic Access Cavity Preparation Armamentaria Access Cavity Objectives (1) Caries removal. Why? To eliminate mechanically as many bacteria as possible from the interior of the tooth To assess restorability (2) To conserve sound tooth structure (3) To completely unroof the pulp chamber & to remove all coronal pulp tissue (vital or necrotic) Access Cavity Objectives (4) To locate all root canal orifices (5) To achieve straight- or direct-line access to the apical foramen or the initial curvature of the canal to reduce the risk of file breakage  Access Cavity Objectives Guidelines Important clues to the location of orifices and to the type of canal system Principles of Endodontic Access Cavity Preparation Armamentaria Access Cavity Guidelines 1) Visualization of the Likely Internal Anatomy 2) Evaluation of the Cementoenamel Junction and Occlusal Anatomies 3) Preparation of the Access Cavity through the Lingual and Occlusal Surfaces 4) Removal of All Defective Restorations and Caries before Entry into the Pulp Chamber 5) Removal of unsupported tooth structure 6) Creation of access cavity walls that do not restrict straight or direct-line passage of instruments to the apical foramen or initial canal curvature 7) Location, Flaring, and Exploration of All Root Canal Orifices 8) Inspection of the Pulp Chamber, Using Magnification and Adequate Illumination 9) Irrigants, dyes, light, and transillumination can also help in root canal localization 10) Evaluation of Space Adequacy for a Coronal Seal Access Cavity Guidelines 1) Visualization of the Likely Internal Anatomy Radiographically: Diagnostic radiographs help the clinician estimate the position of the pulp chamber, the degree of chamber calcification, the number of roots and canals, and the approximate canal length Clinically: Examining tooth anatomy at the coronal, cervical, and root levels Access Cavity Guidelines 2) Evaluation of the Cementoenamel Junction and Occlusal Anatomies Krasner and Rankow found that the (CEJ) was the most important anatomic landmark for determining the location of pulp chambers and root canal orifices. They proposed nine guidelines, or laws, of pulp chamber anatomy to help clinicians determine the number and location of orifices on the chamber floor 1. Law of centrality 2. Law of concentricity: 3. Law of the CEJ 4. First law of Symmetry 5. Second law of Symmetry 6. Law of color change 7. First law of orifice location 8. Second law of orifices location 9. Third law of orifices location  Access Cavity Guidelines 2) Evaluation of the Cementoenamel Junction and Occlusal Anatomies Guidelines of Krasner and Rankow 1. Law of centrality: The floor of the pulp chamber is always located in the center of the tooth at the level of the CEJ 2. Law of concentricity: The walls of the pulp chamber are always concentric to the tooth’s external surface at the level of the CEJ; that is, the external root surface anatomy reflects the internal pulp chamber anatomy 3. Law of the CEJ: The distance from the external surface of the clinical crown to the wall of the pulp chamber is the same throughout the circumference of the tooth at the level of the CEJ, making the CEJ the most consistent repeatable landmark for locating the position of the pulp chamber  Access Cavity Guidelines 2) Evaluation of the Cementoenamel Junction and Occlusal Anatomies Guidelines of Krasner and Rankow 4. First law of Symmetry: Canal orifices are equidistant from a line drawn in a mesiodistal direction through the pulp-chamber floor (exception: maxillary molars). 5. Second law of Symmetry: Canal orifices lie on a line perpendicular to a line drawn in a mesiodistal direction across the center of the floor of the pulp chamber (exception: maxillary molars).  Access Cavity Guidelines 2) Evaluation of the Cementoenamel Junction and Occlusal Anatomies Guidelines of Krasner and Rankow 6. Law of color change: The pulp chamber floor is always darker in color than the walls. 7. First law of orifice location: The orifices of the root canals are always located at the junction of the walls and the floor 8. Second law of orifices location: The orifices are located at the angles in the floor-wall junction 9. Third law of orifices location: Canal orifices are located at the terminus of the root development fusion lines (Developmental grooves) Access Cavity Guidelines 3) Preparation of the Access Cavity through the Lingual and Occlusal Surfaces Anterior: through the lingual tooth surface Posterior: through the occlusal surface These approaches are the best means of achieving straight- line access and diminishing Esthetic and Restorative concerns. Access for mandibular incisors can be moved from the lingual surface to the incisal surface. This allows better access to the lingual canal and improves canal debridement. Access Cavity Guidelines 4) Removal of All Defective Restorations and Caries before Entry into the Pulp Chamber If restorations are not completely removed, you can miss fractures, caries, and marginal breakdown Working through restorations also allows restorative debris to become more easily lodged in the canal system Removal of caries prevents: Irrigating solutions from leaking past the rubber dam into the mouth Carious dentin and its bacteria from entering the root canal system. Access Cavity Guidelines 5) Removal of unsupported tooth structure The clinician should remove all unsupported tooth structures to assess restorability and to prevent tooth fracture during or between procedures. Access Cavity Guidelines 6) Creation of access cavity walls that do not restrict straight or direct-line passage of instruments to the apical foramen or initial canal curvature Sufficient tooth structure must be removed to allow instruments to be placed easily into each canal orifice without interference from canal walls, mainly when a canal curves severely or leaves the chamber floor at an obtuse angle. Failure to follow this guideline results in treatment error, including root perforation, ledge formation, and apical transportation. Access Cavity Guidelines 7) Location, Flaring, and Exploration of All Root Canal Orifices A sharp endodontic explorer (DG-16) is used to locate canal orifices. Next, all canal orifices and the coronal portion of the canals are flared to make instrument placement easier. The canals are then explored with small, pre-curved K-files (#6, #8, or #10). Access Cavity Guidelines 8) Inspection of the Pulp Chamber, Using Magnification and Adequate Illumination DOM Surgical loupes and dental operating microscope (DOM) are available instruments to help the clinician accomplish these goals. A clinician trained in microscopic techniques has a better Dental loops chance of locating and negotiating intricate root canal systems. Access Cavity Guidelines 9) Irrigants, dyes, light, and transillumination can also help in root canal localization A drop of sodium hypochlorite (NaOCl) can be placed in the pulp chamber and viewed under the DOM. The solution will often bubble and “light up” a canal orifice Transillumination of the pulp chamber with a curing light has also been suggested to help locate root canal orifices Caries detection dye or other stains can also locate hard-to-find root canal orifices  Access Cavity Guidelines 10) Evaluation of Space Adequacy for a Coronal Seal A proper access cavity At least 3.5 mm of temporary filling material (e.g., Cavit) is needed to provide an adequate coronal seal for a short time. https://www.semanticscholar.org/paper/Estimation-of-tertiary-dentin-thickness-on- pulp-Riyadi-Azizah/6bdf08e947d3eb8796ee4c3e75be37f640a0ccea/figure/0  Access Cavity Objectives Guidelines Important clues to the location of orifices and to the type of canal system 1. Examination of the pulp chamber floor 2. The relationship of orifices to each other. Principles of Endodontic Access Cavity Preparation Armamentaria  Buccal Access Cavity Palatal Important clues to the location of orifices and to the type of canal system 1)Examination of the pulp chamber floor If only one canal is present, it is usually located in the center of the access preparation Oval shaped orifice, must be explored with apically pre-curved small K-files If only one orifice is found and it is not in the center of the root, another orifice probably exists, and the clinician should search for it on the opposite side Access Cavity Important clues to the location of orifices and to the type of canal system 2) The relationship of orifices to each other. The closer the orifices, the greater the chance the two canals join at some point in the body of the root. As the distance between orifices in a root increases, the greater the chance that the canals will remain separate. The more separation between orifices, the less the degree of canal curvature.  Access Cavity Objectives Guidelines Important clues to the location of orifices and to the type of canal system Principles of Endodontic Access Cavity Preparation Armamentaria Access Cavity Principles of Endodontic Access Cavity Preparation Established by G. V. Black I. Outline Form II. Convenience Form III. Removal of the remaining carious dentin IV. Toilet of the cavity Access Cavity Principles of Endodontic Access Cavity Preparation - I Principle: Outline Form Outline form is a projection of the internal anatomy of the pulp onto the external structure The outline form ensures the correct shape and location and provides straight-line access to the apical portion of the canal or to the first curvature. Access Cavity Principles of Endodontic Access Cavity Preparation I Principle: Outline Form The form can change with time. eg: in anterior teeth with mesial and distal pulp horns, the access is triangular. In older individuals with chamber calcification, the pulp horns are absent, so the access is ovoid. Factors regulating outline form 1. The size of the pulp chamber 2. The shape of the pulp chamber 3. The number of root canals, their curvature, and their position Access Cavity Principles of Endodontic Access Cavity Preparation - II Principle: Convenience form Modification of the ideal O.F. to facilitate unstrained instrument placement and manipulation. As an example, the use of nickel–titanium rotary instruments requires straight-line access. An access might be modified to permit placement and manipulation Access Cavity Principles of Endodontic Access Cavity Preparation - II Principle: Convenience form A maxillary premolar exhibiting three roots. The outline form might be made more triangular to facilitate canal location Failure to properly modify the access cavity outline by extending the convenience form will ultimately lead to failure by either root perforation, “ledge” formation within the canal, instrument breakage, or the incorrect shape of the completed canal preparation, often termed “zipping” or apical transportation.  Access Cavity Principles of Endodontic Access Cavity Preparation - III Principle: Removal of the Remaining Carious Dentin Caries and defective restorations must be removed : (1) to eliminate mechanically as many bacteria as possible from the interior of the tooth. (2)To eliminate the discolored tooth structure, that may ultimately lead to staining of the crown, (3) to eliminate the possibility of any bacteria-laden saliva leaking into the prepared cavity. (4) To assess restorability After the caries are removed, if a carious perforation of the wall is allowing salivary leakage, the area must be repaired with cement, preferably from inside the cavity. Access Cavity Principles of Endodontic Access Cavity Preparation - IV Principle: Toilet of the cavity Irrigation, washing out necrotic materials and debris BENEFITS: 1- Flushing debris from pulp chamber 2- Improves visibility 3- Acts as lubricant for instrument penetration in root canal  Access Cavity Objectives Guidelines Important clues to the location of orifices and to the type of canal system Principles of Endodontic Access Cavity Preparation Armamentaria Access Cavity Dental loops Armamentaria Magnification and Illumination Handpieces DOM Burs: Round Carbide burs are useful for penetrating through the roof of the pulp chamber and for removing the roof. Some clinicians prefer to use a Fissure Carbide bur or a Diamond bur with a rounded cutting end to perform these procedures #2, #4, and #6 round carbide burs Tapered stone #57 fissure with round end carbide bur Access Cavity Armamentaria Burs: Non-Cutting tip Fissure Carbide and diamond burs with safety tips (i.e., they do not have a cutting end) are safer choices for axial wall extensions to prevent perforation of the pulp chamber Endo Z bur Safe end tapered stone Trans-metal Bur: It is excellent due to its exceptional cutting efficiency for cutting through metallic restorations such as amalgams, all-metal cast restorations, or metal copings of porcelain fused to metal crowns. Trans-metal bur Access Cavity Armamentaria Burs: - Round Diamond Burs (sizes #2 and #4) are needed for endodontic access through porcelain or Metalloceramic restorations. Diamond burs are less traumatic to porcelain than carbide burs and are more likely to penetrate the porcelain without cracking or fracturing. Carbide bur, such as transmetal bur, is used for metal or dentine penetration because this bur has greater cutting efficiency #2 and #4 round diamond burs Access Cavity Armamentaria Burs: - Mueller Bur and LN Bur: Extended-shank round burs are very useful if a tooth has a receded pulp chamber and calcified orifices, the clinician often must cut into the root to locate and identify the canal orifices. Mueller bur NL bur Access Cavity Armamentaria Burs: Gates-Glidden burs - Gates-Glidden Burs or Orifice Shaper (Taper Nickel–Titanium Orifice Opener): Once the orifices have been located, they should be flared or enlarged and blended into the axial walls of the access cavity. This process permits the intracanal instruments used during shaping and cleaning to enter the canal(s) easily and effortlessly. #.12 taper nickel– titanium orifice opener Access Cavity Armamentaria Burs: - Gates-Glidden Burs or Orifice Shaper (Taper Nickel–Titanium Orifice Opener): When using either of these two techniques for canal flaring, the clinician must guard against removing excessive dentin on the furcation side of a root canal, which could create a “strip” perforation. Access Cavity Armamentaria Endodontic Explorer, Endodontic Spoon, #17 Operative Explorer: DG-16 endodontic explorer (top), CK-17 - Endodontic Explorer: endodontic explorer (bottom) The DG-16 endodontic explorer is used to identify canal orifices. The CK-17 endodontic explorer serves the same purpose, but its thinner, stiffer tip can be useful for identifying calcified canals. - Endodontic Spoon Excavator The endodontic spoon can be used to remove coronal pulp and carious dentine. Access Cavity Armamentaria Endodontic Explorer, Endodontic Spoon, #17 Operative Explorer: - #17 Operative Explorer: It is useful for detecting any remaining pulp chamber roof, particularly in the area of a pulp horn Access Cavity Armamentaria - Ultrasonic Unit and Tips: It is useful for detecting any remaining pulp chamber roof, Endodontic ultrasonic tips particularly in the area of a pulp horn Ultrasonic systems provide excellent visibility compared with conventional handpiece heads, which typically obstruct vision. Fine ultrasonic tips are smaller than conventional round burs. Endodontic ultrasonic unit Access Cavity Armamentaria - Ultrasonic Unit and Tips: Is useful for detecting any remaining pulp chamber roof, particularly in the area of a pulp horn Ultrasonic tips can trough and deepen developmental grooves to remove tissue and explore for canals. The abrasive coatings allow clinicians to sand away dentin and calcifications conservatively when exploring canal orifices. Minimally invasive access cavity preparation??? DEBATE ……. to preserve as much tooth structure as possible, while managing to locate, debride, enlarge, shape, and obturate the root canal(s). However, too restricted access might impact the remaining and important root canal procedures… Definitive, evidence-based outcomes have yet to be seen within this empirically based approach.  References Cohen, Pathways of the Pulp tenth and eleventh edition Principles and practice Torabinejad 5th edition. Thank you