Unusual Anatomy Of The Mandibular First Premolar

On 09/09/2011, in Non-surgical Root Canal, Root Canal Anatomy, by Vladimir Tismensky, DDS

The normal anatomy of the mandibular first premolar is well documented in dental literature and text books.  However, there are variations in the number of roots, canals and foramenas.  A literature review by Cleghorn and Christie in JOE 2007, combining all cited studies with over 6700 teeth revealed the following with regards to the number of canals in the first mandibular premolar:

Single canal – 76% of teeth

Two or more canals – 24% of teeth

Angulated radiographs and their careful interpretation can give us a clue as to the complexity of the root canal space.  Specifically, a sudden disappearance of a canal space in the middle third of the root radiographically is a strong sign of multiple canals.  In addition, the use of the microscope and symmetry laws are especially helpful when unexpected or unusual anatomy is present.  In some cases, a cone beam image may be taken to get a better understanding of a root canal anatomy of a particular tooth.

I saw a 35 year old white male yesterday with irreversible pulpitis on tooth #21. His general dentist referred him for a root canal and noted the unusual anatomy of the pulp space.

Angulated pre-op radiograph reveals presence of more than one canal.

Pre-op tooth #21

Upon endodontic access and microscopic examination, four distinct canals were located and treated. A glass ionomer barrier was placed over the root filling material to augment the seal.

Post-op tooth #21

 

 
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“Water Bending Effect”

On 06/02/2011, in Clinical Tips, Non-surgical Root Canal, Root Canal Anatomy, by Vladimir Tismensky, DDS

I often use images taken with the camera attached to the microscope as part of documentation, communication with the referring dentist or patient education.

In this post, lets pay attention to photographs illustrating the use of a concept of liquid surface tension and cappilary adhesion. I call it a “water bending” or a “prism” effect.

Water, or any liquid for that matter exhibits surface tension which is related to the cohesive properties of water (molecules “stick” to each other), and capillary action which in turn is related to adhesive properties of water (molecules “stick” to the surface of an object).

Case 1

Pre op

Access opening

Note, the image above of an access opening: cant see the canals well unless the walls of the prep would be flared quite a bit.

The image below is taken of the same exact access opening but with a little hypochloride liquid in the access. Due to surface tension and capillary adhesion, the liquid bends inside the prep and with proper illumination we can see all four canals nicely.

Same access with liquid in it

Post op

Case 2

Pre op

Due to a “water bending effect” we can clearly see four canals through a very conservative access opening.

Access, "water bending effect"

 

Post op

The “water bending effect” has limited clinical applications.  Occasionally during apical surgery, I use it to view/detect lingual canals and to see where the ultrasonic tip should go with out changing the position/angle of the microcsope.

Case 3

Image below shows an osteotomy for an apical surgery tooth #14.

Note  minimally angled resection of the MB root (I try to get as close to 90 degrees resection as possible to minimize the number of exposed dentinal tubules), cant see the canals unless we look at this resection from a slightly different angle.

MB root of #14 resected

Next image was taken from the same angle as the first one but with a little saline in the surgical crypt. Now we can see gutta percha/sealer due to a water bending effect, and the ultrasonic instrumentation can immediately start with out repositioning of the microscope.

Water bending effect

MTA in MB1-MB2 with isthmus and DB

 Although its clinical implications are minimal, the “water bending” or a ”prism” effect is really cool and can be used in dental photography as an educational tool.

 
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Maxillary Molar with Two Palatal Roots

On 05/22/2010, in Non-surgical Root Canal, Root Canal Anatomy, by Vladimir Tismensky, DDS

Maxillary molar with four distinct roots is a rarity!

The overall incidence of four-rooted maxillary molars has been reported to be less than 0.4%. Nevertheless, dentists should be aware of such variation.

When examining the pre-operative periapical radiographs of maxillary molars, if the outlines of the roots are unclear, the root canals show sharp density changes, or the apices cannot be well defined, then extra roots can be suspected! Horizontally angulated radiographs can also be helpful to distinguish the multiple root morphology of maxillary molars. Most definitive means however is visualizing the “road map” on the pulp chamber floor.

The following two cases had pulp chambers shaped like a quadrangle with one orifice in each corner.

Case 1: Tooth #14 (palatal roots length: 23mm on both)

Pre-op

Post-op

Case 2: Tooth #15 (palatal roots length: 25mm MP and 24mm DP )

Pre-op

Post-op

In both cases canals were instrumented with a combination of hand files and Protaper rotary instruments and sealed with Resilon cones and sealer using warm vertical condensation.

 
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Nice Periapical Healing

On 03/30/2010, in Non-surgical Root Canal, Root Canal Anatomy, by Vladimir Tismensky, DDS

Tooth #4
Necrotic pulp with asymptomatic periapical periodontitis.

Pre-op

Instrumentation was completed with protaper instruments and hand files in the apical third.

Post-op

Warm vertical condensation using Resilon cones and sealer.

Follow-up 6 months

 
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