10 Difficulties And Solutions For Root Canal Treatment_News & Events

Discovery of missing root canals

Missing root canals are one of the common reasons leading to failure of root canal treatment. X-ray apical film is the main method to judge the missing root canals. Regardless of the X-ray transillumination angle, when there is only one root canal in the root, the image of the root canal is always located in the center of the root. When the X-ray film shows that the root canal image is not in the center of the tooth root, there should be a high degree of suspicion that there are other root canals. X-ray offset projection (medium or distal) is the most effective way to show and judge the existence of the missing root canal, and to determine the position of the missing root canal (buccal or tongue). In addition, X-ray offset projection can separate overlapping root canal images, determine the direction and degree of curvature of the root canal, determine the location of foreign bodies and perforations in the root canal, and locate the direction of the calcified root canal.

For a single tooth, if the root canal image changes suddenly, the following conditions are indicated:

1) Two root canals are separated from the wide medullary cavity;

2) A wide root canal is divided into two root canals;

3) The overlapping double canals of the premolar and lower anterior teeth begin to separate.

When using X-ray diagnostic wire, if there is another transmission line parallel to the diagnostic wire (root canal image) in the upper middle of the root canal, the other tube should be highly suspected. In addition, familiarity with the anatomy of the pulp cavity root canal system and observing the changes in the position of the root canal orifice will also help to find the missing root canal.

Treatment of calcification and curved root canals

Root canal calcification is a frequently encountered problem in root canal treatment. It can cause the root canal to be blocked and even difficult to find the root canal orifice. Pulp calcification is the pathological process of pulp being subjected to external stimuli. The degree of calcification is related to different stimuli, and the difficulty of clinical treatment is also different. For curved calcified root canals, the opening of the pulp hole should be as convenient as possible, removing all the pulp top, and sometimes more dental tissue needs to be sacrificed. The wall of the pulp hole should form a straight channel with the wall of the root canal. Finding and determining the root canal orifice is the key first step in the treatment of calcified root canals. The most important tools are the straight dental tip probe and the root canal probe. The bottom of the pulp chamber is hard dentin. The probe can enter the root canal orifice a little under certain pressure, and it will feel stuck. At this time, X-ray is used to determine whether it is a root canal orifice. If necessary, a microscope should be used to confirm. Most of the root canal orifice is bent at 1~2mm, and the dentin of the neck should be removed; if the root canal orifice is still not found, you can use 2# oblong drill or ultrasound to enter the root canal orifice for 1~2mm. The black pulp chamber floor and white restorative dentin are the signs of finding the root canal orifice. Root canal lubricants (including EDTA) are helpful for finding root canal openings.

Discovery and treatment of the second canal (mb2) of the mesial buccal root of upper molars

Clinically, after root canal treatment of some maxillary molars, the mesial buccal root apical lesions still exist or form new lesions, which are often caused by missing MB2. In the past, it was reported that the incidence of MB2 was 51.5%-95.2% in isolated teeth and 18.6%-77.2% in clinic. The clinical treatment rate of mb2 can reach more than 90% with microscope. The root canals of the mesial buccal root of maxillary molars can be divided into 4 types:

Type 1: From one root canal to one apical hole;

Type 2: Enter from two root canal openings, but merge into a single canal above the apical foramen to form a apical foramen;

Type 3: Two root canal openings and two apical holes form two independent root canals;

Type 4: Two apical holes are formed from one root canal orifice into the root.

The root canal of MB2 is located in the mesial buccal root canal orifice, and the distance between MB2 and MB is (0.93~2.01)mm. The MB2 root canal orifice is located in the mesial of the line connecting the mesial buccal root and the palatal root (MB-P), and the vertical distance from the line of MB-P is (0.25~0.81) mm. The angle between MB-MB2 and MB-P connection is 9.99~36.15 degrees.

Clinical examination of MB2: When X-rays parallel or offset projections reveal that the root canal image or the diagnostic wire is not in the center of the root canal, the presence of MB2 should be highly suspected. The relationship between MB2 and other root canal orifices should be followed. Ultrasound or oblong should be used. Drill along the mesial side of the MB-P connection line and properly remove the dentin by 1～2mm, then you can find the root canal opening with DG16 probe or root canal probe. It is best to use 08# or 10#K file combined with root canal lubrication. The agent expands the root canal. Attention should be paid to avoid over-seeking, resulting in bottom or side wear.

Discovery and treatment of C-shaped root canals of mandibular molars

C-shaped root canals mostly occur in the mandibular second molars. The incidence of C-shaped root canals in the mandibular second molars is very high in the Chinese population, ranging from 15.8% to 45.5%, which is significantly higher than that of European and American populations (below 8%). Due to the complex root canal morphology, and the occurrence of root canal variation such as higher auxiliary root canals, communicator apical triangles, etc., it is easy to cause missing root canals or three-dimensional imperfect root canal filling. Therefore, the treatment of c-shaped root canals is considered to be correct A challenge for clinicians.

Due to the special shape of the C-shaped root canal, in order to show the characteristics of the C-shaped root canal, Melton et al. classified the cross-sectional shape of the C-shaped root canal in 1991. In 1999, Haddad participated in the classification of the C-shaped root canal. Divided into three types:

Type 1: A continuous C-shape from the orifice of the root canal to the apical hole;

Type 2: The root canal orifice is in the shape of a semi-sign, and there is dentin to separate the independent mesial canal orifice from the distal C-shaped root canal orifice;

Type 3: Root canals are discontinuous, arranged in a C shape, and divided downward into independent 2 or 3 root canals.

Many scholars believe that X-rays cannot be used to diagnose it, but we have found through research that horizontal projection X-rays before C-shaped root canal surgery have the following characteristics:

Root characteristics:

a. It presents a single root, tapered root tip, square round or nodular shape, with a cord or spindle-shaped X-ray density reduction zone in the middle.

b. Like double roots, the root tips are wider and square, and there are periodontal ligament images between the "double roots" root tips; the bone trabecula, periodontal ligament and "root divergence" between the "double roots" are displayed Unclear.

Features of medullary cavity:

a. In a single conical root, it is often seen that the images of the two tubes are close to the 1/3 area of the root tip and merge into the low-density area of X-ray.

b. A small and fuzzy third canal image can be seen between the mesial and far root canal images.

These X-ray features help to determine the existence of C-shaped root canals before clinical operation. C-shaped root canals have a relatively high incidence of root canal variation such as accessory root canals, communicating branches, and apical triangles. Therefore, root canals are being performed. During the preparation process, attention should be paid to the combination of mechanical preparation and chemical preparation. If possible, ultrasonic file and irrigation fluid can be used to wash the root canal. After perfect root canal preparation, it is best to use hot gutta-percha vertical compression method for root filling, so as to better fill the communicating branches and the root canal.

Teeth treatment with undeveloped root tips

Incomplete root apex development can be seen in teeth with inflamed pulp, pulp necrosis, or root apical lesions. The treatment plan should be determined according to the condition of the pulp and the level of root development.

Vitalotomy is used in young permanent teeth with trauma or caries to decompose and expose the pulp. Ca(oh)2 or root canal cement (MTA) can be used to cover the pulp. Regular observations usually take 2 to 3 years for root formation. If it fails , To undergo apexplasty or root canal therapy.

Apexplasty is suitable for young permanent teeth with undeveloped apex. Apexplasty may fail again after the early success in some cases. It may be due to insufficient sealing of the pulp cavity root canal system, re-invasion of bacteria and toxins, or longitudinal or transverse root canal wall fractures, so at least 4 observations should be made. ~5 years.

It should be noted that the perfect cleaning and preparation of the root canal system and the tight filling of the crown are as important as Ca(oh)2 or MTA root tip induction materials.

Apical surgery

After root canal treatment fails, root canal retreatment should be performed first. The success rate of root canal retreatment is more than 60%. Therefore, only a few cases require apical surgery.

Indications for apical surgery:

1. Anatomical factors: such as root canal calcification, blockage and severe bending, inability to complete root canal preparation and filling, and extensive absorption in the apical area, resulting in treatment failure.

2. Accidents during treatment: broken equipment, shoulders, perforations, overfilling lead to treatment failure.

3. Root canal can not be unobstructed: such as post core, silver needle, non-removable root fillings and silver mercury hinders retreatment of the root canal.

4. Symptoms persisted: After perfecting root canal treatment, the symptoms did not improve for a long time. After excluding various possible factors, apical surgical exploration can be considered to find and deal with possible causes: such as missing longitudinal root canal, missing accessory apical foramen, Apical bifurcation, perforation, overfilling and other reasons.

Contraindications of apical surgery:

First of all, attention should be paid to the patient's general condition, and non-surgical indications should be excluded. Secondly, the location of the affected tooth, the maxillary sinus and the mandibular neural tube, and the short root of the affected tooth and severe periodontal disease are all prohibited for apical surgery.

Precautions for apical surgery:

1. Length and angle of apical resection: 3mm parallel resection of the apical area can remove more than 93% of the collateral root canals, which is the appropriate length of resection. The traditional resection slope is 45 degrees, which is convenient for observation and operation. At present, the resection surface less than 10 degrees is considered ideal.

2. Apical preparation: The ideal method is to prepare the head with ultrasonic inversion, prepare 3mm along the direction of the root canal, remove the contents of the root canal and prepare the root canal to form an inverted filling retention shape.

3. Apical inverted filling materials: There are many inverted filling materials, such as silver mercury, glass ionomer cement, IRM, Super-EBA and MTA. The most ideal material at present is MTA.

4. It is very important to stop bleeding during root apical surgery. Epinephrine-containing anesthetics can be used to press the adrenaline-containing gauze into the bone cavity, and ferrous sulfate solution or calcium sulfate can be used to assist hemostasis.

5. At the end of inverted filling, the bone cavity should be flushed with saline before suturing to prevent debris from staying in the bone cavity.

Treatment of internal and external absorption of the tooth root

The reasons for internal and external absorption of the tooth root are different, and the treatment methods and prognosis are also different. Therefore, according to the X-ray and clinical manifestations, the internal and external absorption should be distinguished, and the appropriate treatment method should be selected.

Use the X-ray apex film and bite wing to distinguish the internal and external absorption of the tooth root:

The internal absorption boundary is smooth, the shape is symmetrical, and the root canal at the absorption site is thick;

The outer absorption boundary is rough, the density is different, it is cannibalized, and the shape is asymmetrical. Before the root canal is damaged, the original outline of the root canal can be found.

When shifting the projection, the positional relationship between the internal absorption and the root canal remains unchanged; while the external absorption site changes. Internal resorption starts from the pulp cavity or the inner wall of the root canal, and is related to pulp inflammation and bacterial infection. Generally, there are no symptoms, and most of them are found during X-ray photography. Root canal treatment should be performed as soon as possible. After the infected tissue is removed, the prognosis is good, otherwise further development will cause perforation of the root canal wall.

It is difficult to remove the infected tissue from the internal absorption site. Full washing or ultrasonic washing is an effective cleaning method, and the root canal is sealed with Ca(oh)2 paste for one week before root filling.

Due to the irregular internal absorption, it is best to use the hot gutta percha vertical compression technique for root filling. If the internal absorption is too large and the root canal wall is very thin, excessive pressure should be avoided, and Ca(oh)2 paste and gutta-percha root filling should be used. Root canal wall perforation is relatively small. Ca(oh)2 paste can be used for root filling for 3 months to induce hard tissue formation and then root filling, or MTA root canal filling and repairing.

Larger root canal wall perforations can be repaired by MTA from the root canal or surgically. Apical surgery can be considered for internal absorption near the apical area, and root cutting can be considered for multiple teeth.

Extra-root resorption starts from the periodontal tissue, and the reasons are mostly trauma, excessive correction force, embedded teeth, tooth bleaching, replantation, and periapical inflammation. The treatment method for external absorption in the apical area caused by inflammation of the periapical region is the same as internal absorption. For external absorption caused by other factors, corresponding treatment and root canal treatment are adopted.

Removal of broken instruments

Instrument breakage may occur during root canal treatment, which affects the patency, preparation and perfect filling of the root canal, resulting in treatment failure. Therefore, it is necessary to remove or pass foreign bodies in the root canal. Clinically, there are a variety of methods for removing fractured instruments in the root canal, including ultrasound, H file, cannula, and apical surgery.

Acute attack during root canal treatment

Acute attacks during root canal treatment include pain between appointments and after root canal filling.

Despite the careful manipulation of the treatment process, postoperative pain and swelling are sometimes unavoidable and unpredictable. The vast majority of postoperative reactions are mild discomfort (40%), moderate to severe pain occurs in about 25% of cases, and acute attacks occur in 2% to 4%.

The postoperative response is related to the patient's condition, the condition of the dental pulp and periroot tissue, and the treatment steps. Preoperative pain and swelling, pulp necrosis, or acute apical periodontitis are more likely to have an acute attack. Using long-acting anesthetics, perfecting root canal shaping and cleaning, giving analgesics and preparing patients psychologically can effectively reduce the degree of pain between appointments. Therefore, it is necessary to instruct patients on the condition, degree and duration of pain that may occur after surgery. Preventive use of antibiotics is not effective in reducing postoperative pain and is unnecessary, but for patients with infections or systemic diseases, antibiotics should be used under the guidance of physicians.

Acute apical symptoms or abscess formation should open the medullary cavity or incision and drainage. Aspirin and ibuprofen can be taken for mild to moderate pain; ibuprofen and codeine can be taken for moderate to severe pain. Hormonal drugs are generally not used. In addition, the use of long-acting local anesthetics can also help delay root canal treatment In the pain.

Factors affecting the long-term efficacy of root canal therapy

1. The state of the pulp before root canal treatment: The state of the pulp before root canal treatment is a controversial factor. It is generally believed that the success rate of root canal treatment of vital pulp is higher than that of dead pulp.

2. Apical status before root canal treatment: Apical lesions before root canal treatment will reduce the success rate of root canal treatment by 7.5% to 14%. However, whether the size of apical lesions affects the long-term effect of root canal treatment is still controversial.

3. Root canal preparation methods and filling techniques: There is no significant difference in the effect of different preparation methods on the success rate of root canal treatment; the case of cold side pressure filling has a higher success rate than that of no lateral pressure filling, and the full length of the root canal is more filling than the root canal. The tip filling success rate is high, but the difference is not statistically significant. The size of the main file for root canal preparation has no significant effect on the long-term effect of root canal treatment.

4. Root canal filling material: The combination of gutta-percha tip and root filling paste is the most commonly used clinical method. It is not advisable to simply use paste root filling or silver needle and paste combined root filling has many problems.

5. The filling quality of the apical area: It is divided into two factors: the filling position of the apical area and the filling density of the apical area. The evaluation criteria for the position of the root canal area are relatively consistent in foreign countries: the distance between the root canal filling and the X-ray root apex position is acceptable. Underfilling or overfilling will reduce the effect of root canal treatment. In addition, the non-compact filling of the apical area will significantly reduce the long-term effect of root canal treatment. The root tip area is not densely filled so that microorganisms have room for survival; while the root tip lateral branches have more root canals, and the tissue fluid is easy to infiltrate when the root tip is not densely filled to provide nutrients for the bacteria, which ultimately leads to the failure of root canal treatment.

6. Crown restoration after root canal treatment: Crown restoration should become a necessary step for perfect root canal treatment. If there is no good crown restoration, it will affect the long-term effect of root canal treatment.

7. Accidents in root canal therapy: Lateral penetration and broken instruments in root canal therapy have a certain impact on the effect of root canal therapy. Mainly because it is difficult to prepare, rinse and fill the root canal under side penetration or broken instruments, which leads to an increase in the failure rate of root canal treatment; but with the application of root canal microscope, ultrasound and good repair materials (such as MTA), it can be Accidents in root canal treatment are treated in time, which improves the long-term curative effect.

Through a review of the literature, the above-mentionedThe factors that have a significant impact on the long-term efficacy of treatment are: the filling quality of the apical area, the state of the apex before root canal treatment, and the condition of crown restoration after root canal treatment. Therefore, ensuring the position and three-dimensional compactness of the root canal filling, proper sealing according to the condition of the pulp, and timely crown restoration after treatment and ensuring the quality are the prerequisites for achieving good expectations of root canal treatment.