Root Canals Demystified

The health of your mouth can be directly linked to total body health. Studies have shown that there is a link between gum disease and serious chronic health conditions such as diabetes, heart disease, osteoporosis, respiratory disease and cancer. 

What is a root canal?

In very simple terms, when a tooth has some kind of damage, large decay or disease, it can still be saved by drilling out the pulp and nerve in the root of the tooth, cleaning and shaping the inside of the root canal, filling and sealing the space, and then capping it with a crown to protect and restore the tooth to its original function.

There are three stages in root canal treatment:

Stage 1: involves removal of the dead nerve and the gross infection. An antibiotic medication is left in the canal to help reduce the bacteria. The symptoms usually subside after this. 

Stage 2: this involves further cleaning and shaping of the canals. Certain medications are used to flush out the debris and create a sterile environment to receive the inert filling.

Stage 3: this is the last stage in the completion of treatment which involves filling the canals with an inert filling material. A permanent filling is done to restore the tooth and then it is ready to receive a crown.

What is a smear layer?

Smear layers are created on hard tissues whenever they are cut with hand or rotary instruments. This thin (1-2 microns) layer of denatured cutting debris consists of microcrystalline and organic particle debris. Because it is very difficult to remove, it is often the surface to which restorative materials are cemented. The solubility characteristics, chemical reactivity and the structure-function relationships of this layer have not yet been well-defined. During creation of the smear layer, cutting debris is forced variable distances into dentinal tubules. These so-called smear plugs, together with the smear layer decrease dentin permeability, dentin sensitivity and surface wetness. Bonding adhesive resins to smear layers appears to limit the theoretical bond strength unless the smear layers are loosened or partially removed.

What kinds of chemicals are used in a root canal procedure?

A number of different and toxic substances are used to disinfect, irrigate, fill and seal the root canal. Numerous studies on these chemicals all seem to say that for brief exposure (1-10 minutes, depending on the substance) to the canal, only a small erosion of tissue or bone or inflammation will be caused. There is an agreed understanding that there are no perfect or totally safe alternative products so these products are used for their apparent advantages to the process even though they are cytotoxic and less than perfect for the jobs they are doing (dissolving necrotic tissue, killing bacteria, removing smear layer, and enhancing bond strength). Here are some examples:

RINSES/DISINFECTANTS

Sodium hypochlorite (household bleach) Pictures of accidental extrusion of  NaOCl  

Chlorhexidine gluconate can stain teeth, irritate mouth, cause swelling and dry the mouth

EDTA (ethylenediaminetetraacetic acid) binds and holds onto minerals.

MTAD (mixture of docycycline isomer, citric acid and a polysorbate 80) can cause hypersensitivity, nausea or headaches.   

Calcium hydroxide (NaOCl) can cause ulceration and tissue corrosion (the dentist below lost vision after accidentally splashing calcium hydroxide into her own eye. Even after treatment she had recurring corneal abscesses, fungal infections and keloids forming between her eyeball and eyelid requiring removal ).                                          

CEMENTS/PLUGS/CAPS/SEALERS

MTA (Mineral Trioxide Aggregate) tricalcium oxide, silicon oxide, bismuth oxide, tricalcium silicate and tricalcium aluminate and is popular for direct capping of partial pulpotomy, especially for children. Shown to be 53% cytotoxic; see this study. Summary

Metacresol Acetate’s toxicity is due to denaturation and precipitation of cellular proteins, poisoning all cells directly. It can be absorbed following inhalation, oral, or dermal exposure. Cresol is extremely corrosive and may cause cutaneous damage, and gastrointestinal corrosive injury.

Formocresol (formalin, cresol and glycerine) releases formaldehyde; the American Association of Endodontists in 2017, advise against its use because it demonstrates teratogenicity (birth defects) and tumorigenicity (cancer). It is still in use.

Local drug delivery in endodontics: A literature review

Calcium phosphate cement is non-toxic but tends to be more porous which is not optimal.

Odontopaste is a zinc oxide-based root canal paste steroid with 5% clindamycin hydrochloride and 1% triamcinolone acetonide which disinfects dentinal walls and is used as a therapeutic dressing in prepared canals after pulpectomy and root canal preparation.

ZOE (Zinc oxide eugenol) is usually anti-inflammatory but it can be cytotoxic if used directly on tissue; there are three main reaction types: direct tissue damage, contact dermatitis and allergic reaction.

Glass ionomer (glass polyalkenoate cement) contains alumina, silica, fluoride, phosphate, sodium, calcium or strontium. Fluoride release is enhanced-initial rapid release followed by sustained, lower level release which can cause hypersensitivity to cold foods and beverages.

Resin cement components include barium fluoroaluminosilicate glass, calcium aluminosilicate strontium glass, quartz, colloidal silica, ytterbium(III) fluoride and other glass fillers. A downside to polymers is the possibility of creating monomers which are tumorigenic and carcinogenic.They reduce cell viability, especially of mesenchymal and osteoblastic cells.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7817560/

It is interesting to note that the majority of articles and studies conclude that none of the available sealers prevent leakage consistently. It is impossible to prevent the leakage unless sealer bonds both to the tooth structure and to the core material.

FILLERS

Gutta-Percha is a thermoplastic latex derived from the Palaquium gutta evergreen tree, considered inert and non-toxic.

Polycaprolactone urethane-based resin is a polymer with urethane as one of the ingredients. Urethane contains known respiratory toxins called isocyanates, but dried, it is considered to be non-toxic.

Calcium Hydroxide with Iodoform  is a filler that can decrease viability of macrophages and epithelial cells, lead to irritation of follicles and formation of cyst-like radiolucent defects and can damage liver cells.

Can a tooth survive without the pulp?

The soft tissue inside the tooth root is called pulp and it contains blood vessels, nerves and connective tissue, which help grow the root of your tooth during its development. A fully developed tooth can survive without the pulp because the tooth continues to be nourished by the tissues surrounding it. 

What kind of filler is used in the root canal?

Most commonly, a substance called gutta-percha is used to fill the empty root canal. Gutta-percha is a plastic substance from a Malaysian tree called the percha tree. Although GRAS (generally accepted as safe), gutta-percha does have some disadvantages such as not being strong enough to hold certain procedures and may cause vertical root fractures in a tooth that was previously filled with gutta-percha.

How do you know if you need a root canal?

A few symptoms that may alert the dentist to the option of root canal are:

• Severe pain while chewing or biting
• Pimples on the gums
• A chipped or cracked tooth
• Lingering sensitivity to hot or cold, even after the sensation has been removed
• Swollen or tender gums
• Deep decay reaching the root
• Darkening of the gums
• Mechanical or heat trauma to the tooth

Is a root canal procedure painful?

Patients are given anesthesia, so it feels like other dental procedures such as getting a tooth removed or getting a filling. After the procedure, there may be mild discomfort for a few days.

Is a root canal safe?

Yes and no. Generally, the answer would be yes. Published statistics say that the success rate of root canal therapy is between 85-98%. As a result of certain variables, problems can and do occur. The underlying cause of major complications is harmful bacteria spreading to and through your blood to the rest of your body causing systemic problems. 

1. If the dentist inadequately prepares and disinfects the “dugout”, bacteria can grow and cause infection, inflammation and pain. This infection can move to the bone and cause deterioration of the bone mass and a sepsis issue. Neurotoxic bacteria that cause damage to the root canal can travel from the mouth to the eyes through the lymphatic system and then damage the optic nerve, leading to vision loss.
2. If the crown is loose or cracked, infection can get in and cause the same cycle.
3. Accidental injection of sodium hypochlorite beyond the root apex can cause violent tissue reactions characterized by pain, swelling, hemorrhage, and in some cases the development of secondary infection and paresthesia (burning or prickling sensation in the hands, arms, legs, or feet, but can also occur in other parts of the body).
4. Sinus communication, which is a small hole in the sinus lining which may be opened during the root canal process, which can feel like air rushing over the hole, runny nose or fluid entering your nose when you are drinking.
5. Accidental perforation of the sinus lining during the root canal process, can cause headaches, pressure and/or pain in the sinus.
6. Accumulation of unwanted materials such as cholesterol crystals can irritate tissues where the root canal was done as well as scar tissue or cystic lesions.
7. Zipping, which is caused by using progressively larger and stiffer files to working length, can result in a poorly cleaned root canal which fails to provide resistance form to compact the filler and leads to under-filling, yet, vertical overextension of the filling material.
8. When a dentist uses a revitalizing agent in the pulp, a significant number of patients experience severe post-operative pain and necrosis of gingiva and bone.
9. Some of the rinses, fillers, liners and cements can damage periodontal and bone tissues.

How long do root canals last?

It depends… Statistics say they may last 10 years but some can last 20 or more years, depending on oral hygiene, diet, lifestyle, the strength of the tooth and the quality of the original root canal treatment. Root canals can be redone up to 3 times; after that the tooth will need to be pulled because it will be too weak to provide the resistance needed to hold the filling.

Can a dentist determine if a root canal is in good condition?

With an X-ray, both bone and soft tissue can be seen as well as signs of infection. 

What symptoms may be present when the bone under a root canal is infected?

There may be pain in the mouth or jaw, redness, swelling or drainage of pus that may give an unfamiliar taste in the mouth.

Can bone infection in the mouth be fixed?

Yes. An endodontist can cut out the infected area, carefully and thoroughly scrape the infection off the bone, graft bone and/or tissue, if needed, to fill the space and implant a post. Sometimes the tooth can be saved and a new root canal done after the gums and bone have healed. One or two courses of antibiotics after the gum surgery should be enough to kill the infecting bacteria. A healthy body will then drain the infection out through the sinuses and lymphatic system. 

Summary

Root canal procedures are popular because they save a tooth and are much less expensive than either bridges or implants. As with most procedures, there may be benefits as well as risks. It is up to you to base your decision on your own best interest. The first step is to find a dentist who is experienced and has excellent testimonials or references over time. Do your research and don’t go for the cheapest price! Any time you are doing surgery of any kind in your mouth, it is critical to communicate any conditions, sensitivities, allergies you have and any medications you are on so the dentist can accommodate any possible reactions. Go online to learn about the whole process and ask questions about possible adverse effects, the remedies for them and how the dentist plans to protect you from any negative outcomes.

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