Labial access to lower incisors
Straight line access to root canals is one of the most important factors in modern endodontics (S Patel & J. Rhodes British Dental Journal 203). It prevents instruments from working under high stress and helps to avoid separation. It also prevents iatrogenic mistakes such as ledging, zipping perforations and separations of instruments.
For most of the teeth, straight line access is easily done, especially when working with magnification and under the rubber dam. For lower incisors, however, there are no clear guidelines on how to approach root canal treatment and lingual access is very popular.
In my clinical practice over the past 10 years, all root canal treatments are done with the use of a microscope. Initially, lower incisors were treated with lingual access, as I was taught in dental school. However, this provided poor visualisation of the root canal system and I was hardly able to find, and never able to clearly see, two canals. This was frustrating as I was not gaining much from using a microscope.
This made me think that there must be better way of doing root canal treatment in lower incisors and to visualise both canals, especially since about 40 per cent of lower incisors present two canals. Those are located in labial and lingual direction. Early articles that I found helped a great deal. First, in 1985, clinicians LaTurno SA, Zillich RM said: “A radiographic analysis of lower incisors conclude that a more labial orientation of the access opening would provide straight-line access to the canal more consistently than the ‘traditional’ lingual access opening. The more labial placement of the access opening on mandibular anterior teeth will make endodontic treatment more efficient and may, therefore, increase endodontic success rates in these teeth.”
In 1989, Madjar D, Kusner W, Shifman A wrote that labial endodontic access is an alternative to the conventional lingual endodontic access in permanent teeth. The labial approach facilitates visibility and provides direct access to the root apex. Current restorative procedures offer improved methods to overcome the aesthetic impairment from this approach. Labial access is especially beneficial for patients with limited mandibular opening.
Other research – carried out in 1991 by Clements RE and Gilboe DB in Canada on access for root canal treatment for lower incisors – found that this approach facilitates the identification and instrumentation of two canals, if present, and makes complete obturation easier. More coronal tooth structure is preserved, enabling an optimum core design for bracing the root.
As a result of my reading about alternative access, my clinical practice has changed dramatically and now all lower incisors are treated with labial access. Surprisingly, no patient has questioned why the tooth is accessed from the visible side and none had any aesthetic complaints after treatment. I believe this is because a wide selection of composite materials and constantly developing techniques make the access cavity invisible.
I recently reviewed a case treated a few years ago. Review X-rays showed excellent healing of a large apical lesion, thanks to good access to apical area during treatment. Labial access was most helpful here and I could only get this result due to the alternative modern approach. Use of the Zeiss microscope and rotary instruments from Dentsply were also useful.
If we analyse the lower incisor anatomy radiologically, we can see that labial access provides straight line access. And if we draw a line on the X-rays from apex to coronal part, it shows that access cavity projects labially in those teeth.
Surprisingly, all new VTs that I meet on my endodontic study days at Glasgow Dental Hospital’s Postgraduate Centre have never heard of labial access. However, most of them, after the study day and a short exercise on extracted teeth, are happy to give it a go. All say it is a lot simpler and they will be able to restore the access cavity with composite material.
I hope this short article provides another option to clinicians undertaking endodontic procedures.
About the author
Having undergone extensive postgraduate training in endodontics, Dr Paradowski gained an MSc in endodontology at the University of Chester in 2012. Shortly after graduation in 1999 from Medical and Dental University in Szczecin and VT training in Poland, Marcin performed his first root canal treatment, using a Leica surgical microscope. He has used a surgical microscope for this procedure ever since and tested several brands of surgical microscope for his MSc dissertation. Marcin has trained in oral surgery for more than three years, including surgical endodontics in his native Poland. Hours spent in oral surgery, maxillofacial units and general surgery wards have seen him achieve success with difficult surgical treatments. Postgraduate courses in Germany increased his knowledge in restorative dentistry and, since moving to Scotland, he has become a VT trainer and runs study days for VTs at Glasgow Dental Hospital. Contact Marcin at firstname.lastname@example.org