Dentists from RUDN University presented a new classification of root canal shape changes

 

RUDN UNIVERSITY

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IMAGE: INDIVIDUAL CHARACTERISTICS OF THE SHAPE AND CROSS-SECTION OF THE ROOT CANAL ARE ONE OF THE MAIN ISSUES FOR DENTISTS. WHEN TREATING A ROOT CANAL, A DOCTOR NEEDS TO PROPERLY CLEAN... view more 

CREDIT: RUDN UNIVERSITY

Individual characteristics of the shape and cross-section of the root canal are one of the main issues for dentists. When treating a root canal, a doctor needs to properly clean it, fill it, and carry out a rebuilding procedure so that a canal is sealed. The first stage of endodontic treatment requires detailed knowledge of root canal anatomy. A team of dentists from RUDN University studied and classified various changes in root canal shapes. The new classification will help doctors avoid diagnostic errors, better select their tools, and treat patients more efficiently. The results of the work were published in the Applied Sciences journal.

A root canal is a hollow space in a dental root with blood vessels and nerves going through it. Root canals have different shapes and width which makes treating them extremely complicated. Turns and shape changes can occur both in the coronal (visible) part of a tooth and in other parts that are invisible to the eye. Previous studies were focused on the curvatures of root canals in either the upper (coronal) or the lower (apical) part of a tooth. But a team of dentists from RUDN University carried out large scale research and presented the first-ever classification of root canal shape changes along its whole length.

"Earlier researchers tended to study about one-third of the root canal: either its coronal or its apical part. However, its shape changes along its full length, and this is an important factor for therapy. That is why we decided to take a look at the variations of root canal cross-sections in all three thirds and in different age groups of adult patients. Our goal was to develop a new classification of root canal shape changes," said Svetlana Razumova, MD, a Head of the Department of Propaedeutics of Dental Diseases at RUDN University.

The team conducted an experiment that involved 300 patients from 20 to 70 years of age. The medics took CT scans of their healthy teeth in axial projection, i.e. the X-ray from the CT scanner moved along the roll axis of the teeth. This way the images showed the cross-sections of root canals. The team took 4,805 images in total and used them to study the changes in the shape of root canals depending on the part of a tooth. The images were processed using statistical methods.

The most widely spread changes in all age groups affected premolars (the teeth situated between canines and molars). In over 50% of cases, the shape of the root canal in premolars changed from round in the apical third into oval in the coronal third. Another place with frequent changes in root canal shapes was mandibular molars.

Based on the obtained data the team developed a classification of root canal shape changes. The medics suggested dividing all possible changes into four groups: 1 - no changes in the shape, 2 - changes in the middle part of the root canal, 3 - changes in the middle and apical parts of the root canal, and 4 - changes in the apical part only. This classification will help dentists better understand the structure of each particular root canal and select proper tools to work with it.

"Our studies show that the shapes of root canal cross-sections can vary depending on the part of the canal and the age of a patient. All these variations were included in our classification and should be taken into consideration when choosing a method for canal cleaning. The choice of tools and preparation methods determines the efficiency of treatment at this stage and therefore affects the whole prognosis," added Svetlana Razumova.

Breakthrough for tomorrow's dentistry

KAROLINSKA INSTITUTET

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IMAGE: KAJ FRIED, PHD, PROFESSOR, DEPARTMENT OF NEUROSCIENCE (TO THE LEFT). IGOR ADAMEYKO, PROFESSOR, DEPARTMENT OF PHYSIOLOGY AND PHARMACOLOGY. view more 

CREDIT: GUSTAV MARTENSSON

New knowledge on the cellular makeup and growth of teeth can expedite developments in regenerative dentistry - a biological therapy for damaged teeth - as well as the treatment of tooth sensitivity. The study, which was conducted by researchers at Karolinska Institutet, is published in Nature Communications.

Teeth develop through a complex process in which soft tissue, with connective tissue, nerves and blood vessels, are bonded with three different types of hard tissue into a functional body part. As an explanatory model for this process, scientists often use the mouse incisor, which grows continuously and is renewed throughout the animal's life.

Despite the fact that the mouse incisor has often been studied in a developmental context, many fundamental questions about the various tooth cells, stem cells and their differentiation and cellular dynamics remain to be answered.

Using a single-cell RNA sequencing method and genetic tracing, researchers at Karolinska Institutet, the Medical University of Vienna in Austria and Harvard University in the USA have now identified and characterised all cell populations in mouse teeth and in the young growing and adult human teeth.

"From stem cells to the completely differentiated adult cells we were able to decipher the differentiation pathways of odontoblasts, which give rise to dentine - the hard tissue closest to the pulp - and ameloblasts, which give rise to the enamel," say the study's last author Igor Adameyko at the Department of Physiology and Pharmacology, Karolinska Institutet, and co-author Kaj Fried at the Department of Neuroscience, Karolinska Institutet. "We also discovered new cell types and cell layers in teeth that can have a part to play in tooth sensitivity."

Some of the finds can also explain certain complicated aspects of the immune system in teeth, and others shed new light on the formation of tooth enamel, the hardest tissue in our bodies.

"We hope and believe that our work can form the basis of new approaches to tomorrow's dentistry. Specifically, it can expedite the fast expanding field of regenerative dentistry, a biological therapy for replacing damaged or lost tissue."

The results have been made publicly accessible in the form of searchable interactive user-friendly atlases of mouse and human teeth. The researchers believe that they should prove a useful resource not only for dental biologists but also for researchers interested in development and regenerative biology in general.

One in 10 older dental patients inappropriately prescribed opioids

 

Combinations with psychiatric meds among most dangerous

A new study by researchers at the University of Illinois Chicago and the University of Pittsburgh suggests that a significant proportion of older patients receiving opioids at dental visits also use psychotropic medications -- a potentially harmful combination. Their findings are published in the journal Pharmacotherapy.

Rates of polypharmacy, or taking multiple medications, are high among older adults who are more likely to be managing more than one health issue at any given time. Psychotropic medications that act on the central nervous system, such as antianxiety or antidepressant medications, are especially dangerous if taken with opioids because they can interact with each other and have negative effects.

"Some of the most concerning negative outcomes of these combinations include overdosing on opioids or falling, which can necessitate a visit to the hospital, which in itself carries greater risk for older adults," said Gregory Calip, associate professor of pharmacy systems, outcomes and policy at the UIC College of Pharmacy and corresponding author on the paper.

The researchers looked at medical, dental and pharmacy claims data from 40,800 older adult dental patients who visited a dentist between 2011 and 2015 and were prescribed opioids. The data was from the IBM Watson MarketScan databases.

The average age of the patients included in the study was 69 years old and 45% were female. Of these patients, 10% were taking medications that are associated with increased risks for harm with opioid prescriptions.

There were a total of 947 hospitalizations or emergency room visits among these patients.

The researchers found that among patients prescribed opioids by their dentist, 1 in 10 were already taking a prescription medication that should not be prescribed with opioids.

They also found that patients inappropriately prescribed an opioid medication combination by their dentist were 23% more likely to be hospitalized or visit an emergency department in the 30 days after the dental visit where they were prescribed an opioid, compared with dental patients who were not prescribed an opioid medication.

"Dentists are among the top prescribers of opioids," said Katie Suda, professor of medicine at the University of Pittsburgh School of Medicine and principal investigator of the study. "It seems that the increased messaging regarding limiting opioid prescriptions has been aimed primarily at medical physicians and not tailored to other specialist providers, including dentists. This can have dire consequences. As we saw in our study, opioid interactions with other medications was likely responsible for the significant rise in emergency room visits and hospitalizations."

"Although the percentage of opioids prescribed by dentists has decreased in the last 20 years, dentists must continue interprofessional collaboration with primary care physicians, pharmacists, and other health care providers to address devastating and preventable drug interactions affecting vulnerable patients who look to them for safe and compassionate care," said Dr. Susan Rowan, executive associate dean and associate dean for clinical affairs at the UIC College of Dentistry.

Botox for TMJ disorders may not lead to bone loss in the short term, but more research is needed

 

Low-dose botox injections for jaw and facial pain not linked to bone changes, but NYU Dentistry researchers observe reduced bone density at higher doses

NEW YORK UNIVERSITY

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Botox injections to manage jaw and facial pain do not result in clinically significant changes in jaw bone when used short term and in low doses, according to researchers at NYU College of Dentistry. However, they found evidence of bone loss when higher doses were used.

The researchers, whose findings are published in the Journal of Oral Health Rehabilitation, call for further clinical studies to track bone- and muscle-related changes with long-term use of Botox for TMJD, or temporomandibular muscle and joint disorders.

TMJDs are a group of common pain conditions that occur in the jaw joint and surrounding muscles, with the most common type involving the muscles responsible for chewing. While many individuals manage their TMJD symptoms with conservative treatments such as jaw exercises, oral appliances, dietary changes, and pain medication, some do not respond to these treatments.

Botox (or botulinum toxin), an FDA-approved injectable drug known for its wrinkle-reducing capabilities, is approved to treat certain muscle and pain disorders, including migraines. It works in part by temporarily paralyzing or weakening muscles. In the U.S., a Phase 3 clinical trial is currently underway to study the use of Botox to treat TMJD, but in the meantime, it is increasingly being used off-label.

Thus far, small studies using Botox to treat TMJD in humans have had mixed results. In animal studies, Botox injections in jaw muscles have led to major bone loss in the jaw. This is thought to be due to the muscles not being used to exert force needed for bone remodeling, but Botox may also have a direct effect on bone resorption, the process of breaking down bone tissue.

"Given these concerning findings from animal studies, and the limited findings from clinical studies, more research on the safety of Botox for jaw muscles and bones is critically important," said Karen Raphael, professor in the Department of Oral and Maxillofacial Pathology, Radiology and Medicine at NYU College of Dentistry and the study's lead author.

The NYU study included 79 women with TMJD affecting their facial muscles: 35 of whom received Botox injections (between two and five rounds in the past year) and 44 who were not treated with Botox but may have used other TMJD treatments. Using specialized CT scans, the researchers measured participants' jaw bone density and volume.

The researchers found that jaw bone density and volume were similar between women who had Botox injections to treat their TMJD and those who did not. While most study participants were given relatively low doses of Botox--smaller than in most clinical trials for TMJD--individuals who received higher doses of Botox were more likely to have lower bone density.

Raphael and her colleagues recommend that more human studies be conducted to better understand the impact of the long-term use of Botox on jaw muscles and bones--and whether it just reduces muscle force on bone or also plays a direct role in altering bone resorption.

"Should Botox receive regulatory approval for the treatment of TMJD, we would recommend that a phase IV study be done using low-radiation CT and MRI to track bone- and muscle-related changes with Botox use, examining both dose and long-term use," said Raphael. "Unless specialized imaging of muscle and bone are conducted among patients who receive Botox treatment over long periods, true cumulative effects will remain unknown."