Difficult lower premolar Flashcards
What are the probabilities of bifurcation of mandibular 1st premolars?
Root canal morphology is unique to each individ- ual tooth. It has been shown to be variable to differ- ent genders as well as races (Caliskan et al. 1995).
The clinician must be familiar with various path- ways root canals take to the apex.The pulp canal system is complex, and canals may branch, divide, and rejoin. Weine (1996) has categorized the root canal systems in any root in four basic types and Vertucci (1984) identified eight pulp space configurations.
Mandibular 1st premolars in particular are known to have complex root canal anatomy, which can make diagnosing and treating the pulp canal space challenging. A good clinician must know the prob- abilities of additional pulp canal spaces in any given tooth before proceeding with the treatment. According to a study on root canal configuration of the mandibular 1st premolar (Baisden, Kulild & Weller 1992), the incidence of one root canal system varied from 69.3 to 86%; two canals, 14 to 25.5%; and three canals, 0.4 to 0.9%.
What are the anatomical and morphological factors to consider before non‐surgical treatment of mandibular premolars?
There are several factors that should be consid- ered, such as gender, race, and position of the tooth in relation to other teeth (Caliskan et al. 1995). In addition, there are certain anatomical factors that are of unique importance to the premolars: (1) position of the inferior alveolar nerve (IAN) in relation to the apex of the tooth; (2) presence or absence of a cortical tunnel around the IAN; and (3) buccolingual and mesiodistal dimension of the root canal system. • Position of the IAN: Before undertaking procedures
on mandibular premolars, it is critical to know the location of the IAN with respect to the surrounding structures to avoid injury. According to Denio, Torabinejad & Bakland (1992), the IAN canal is located buccal to the 2nd molar, lingual to the 1st molar and directly inferior to the 2nd premolar.
• Presence or absence of a cortical tunnel around the IAN:The mandibular canals appear in some cases as distinct bony‐walled channels within porous lined trabecular bone. However, in many cases the canals have no definite borders apical to the 1st molars and 2nd premolars (Denio
et al.1992). Olivier (1927) as well as Carter and Keen (1971), found that 60% of mandible speci- mens contained canals while 40% of the dissec- tions had no distinct canals.These findings suggest that the clinician should identify the canal position and proceed with caution while treating the mandibular premolar.
• Buccolingual and mesiodistal dimension of the root canal system: Non‐surgical treatment of mandibu- lar premolar tooth may pose a challenge to the most skilled clinician.These groups of teeth tend to have a high flare‐up and failure rate.The root canal system of mandibular 1st premolars tends to be wider buccolingually than mesiodistally. If two canals are present, direct access to the buccal canal is usually possible; however, extension of lingual access may be necessary to gain access to the lingual canal (Walton &Torabinejad 1996).
Why is proper imaging important before treating mandibular premolars?
A proper imaging report, and a proper under- standing of the image report, are of paramount importance for a good clinical outcome. Images that can be helpful for treatment of a mandibular premo- lar include intra‐operative periapical radiograph with mesial and distal angles, and CBCT. One good hint of the probability of more than one canal or an acces- sory canal would be the disappearance of a pulp canal midway of the root or at a certain level apically. The prudent decision to follow upon seeing this would be to take multiple‐angled intra‐oral periapical radiographs or a CBCT. The imaging would help the clinician to decide at what distance he/she should look for the additional canal, as well as allow him/her to stay away from danger zones such as the furcation areas, and to detect the presence and severity of concavity of distal surface. Evaluation of CBCT images results in identification of a greater number of root canal systems (Matherne et al. 2008).
What are the essential steps to be taken to successfully treat mandibular premolars?
Cleaning and shaping of the root canal system is a precursor to a well‐obturated and sealed canal, which would be a stepping stone to the longevity and long‐term health of the tooth. Cleaning of the root canal system would include identifying all the canals within the root canal system, and accurately measuring and shaping with a reliable rotary system. Taking these steps will provide the clinician with an area that can be well obturated and sealed three‐ dimensionally. Knowledge of both basic root and root canal morphology as well as possible variation in the anatomy of the root canal system is important to achieve success in non‐surgical root canal treat- ment (Cleghorn, Christie & Dong 2007). Ingle (1961) reported that the most significant cause of endodon- tic failures was incomplete canal instrumentation, followed by incorrect canal obturation. Slowey (1979) has indicated that, probably because of the varia- tions in canal anatomy, the mandibular premolars are the most difficult teeth to treat endodontically. Another step that would aid the clinician in treatment would be the addition of a microscope in the arma- mentarium for better visualization.Tactile sense with a fine, curved stainless steel file is also often the best guide to the detection of the accessory canal sys- tems (England, Hartwell & Lance 1991).
What are the potential consequences of over instrumentation and/or apical sealer extrusion on a mandibular premolar?
Root canal treatment of the mandibular premo- lar presents unique challenges due to its proximity to the IAN canal. Three‐dimensional obturation of the root canal system constitutes one of the goals of endodontic treatment. Ideally, the filling material should be confined to the root canal space without extending to periapical tissues or other neighboring structures (Himel & DiFiore 2009; Gonzalez‐Martin et al. 2010). However, if filling materials are accidentally extruded to neighboring neurovascular structures, nerve injury, with an ensuing altered sensation, may occur (Rosen et al. 2016). Endodontic therapy might also damage the IAN. Several mechanisms have been proposed to explain this damage, including neurotoxic effect from root canal filling material penetrating the IAN (Escoda‐Francoli et al. 2007; Pogrel 2007); mechanical pressure on the nerve caused by over‐extension of filling material or over‐instrumentation with hand or rotary files; or an increase in temperature proximal to the IAN greater than 10° C (Escoda‐Francoli et al. 2007). IAN damage has been suggested to occur in 1% of mandibular premolars that receive root canal treatment (Escoda‐Francoli et al. 2007).
