Anatomical structure of the tooth
Anatomy distinguishes three elements of tooth structure:
Tooth root
- This is an invisible “part” that is hidden in the jaw. A tooth can have from one to three roots, depending on its functions. However, there are known cases when one tooth had up to 5 roots. The root is attached to the alveolus (tooth socket), tightly surrounded by connective tissue.
Tooth neck
- This is the transitional part of the tooth from the root to the crown. It is also covered by the mucous membrane of the gums and connected to the bone substance of the alveoli.
Crown of the tooth
– this is the visible part, in fact, what we call a tooth.
The shape of teeth depends on the functions they perform. Nature has provided for all stages of chewing here.
A man takes a bite of food. The front teeth come into play. They feature a thin edge and cut off pieces of food. Such teeth are called incisors. Then the pieces are sent to the pointed outer teeth. The fangs tear them into smaller pieces. Premolars and molars - large lateral teeth - complete the process - chewing food, grinding it, so that the food ground into porridge is sent into the esophagus.
Central upper incisor
Average age of eruption: 7-8 years
Average age of root formation: 10 years
Average length: 22.5 mm
The crown of the central upper incisor, close to rectangular on the vestibular side and wedge-shaped on the proximal side, allows for convenient endodontic access and is ideally positioned for direct examination using a mirror. The tooth is especially suitable for the novice doctor, since in it the canal is directly visible for a third of its length. With fiber optic illumination, the view of the channel can be improved.
Primary opening using a fissure bur is made immediately above the enamel palatal tubercle of the equatorial third of the crown on the lingual surface of the tooth. The instrument is directed along the long axis of the root. Based on the final shape of the access cavity, a triangular hole is made. Trephination of the tooth cavity often occurs during the first implantation. After the feeling of “falling” into the pulp chamber, the fissure bur is replaced with a spherical bur No. 4-6 with an extended shank.
A ball bur is used to widen the hole towards the incisal edge. You need to make sure that the pulp cavity is completely open. A fissure bur may again be required to widen the access cavity and give it its final shape. At this time, all carious dentin, which has significantly changed its color and pulp calcifications, is removed. It is necessary to remove leaking fillings and treat proximal carious cavities with adequate temporary filling.
The root is quite characteristically cone-shaped and sharply tapering towards the apex. The cross-section of the root canal approaches triangular in the cervical part, gradually becoming rounded closer to the apical foramen. Multiple canals in the root are rare, but accessory and lateral canals are common. The apical foramen is rarely located exactly at the apex, but is usually within 2 mm laterally.
Treatment methods for apical periodontitis of the tooth
How to treat chronic apical periodontitis and how does the treatment method for acute apical periodontitis differ? In both cases, the patient will need several visits to the doctor, since the therapy is carried out in several stages.
- The first stage:
opening the tooth, thoroughly cleaning the dental canals from the remains of necrotic pulp and areas affected by caries. Expansion of channels. - Second stage:
relief of inflammation. It is produced by filling the channels with antiseptic and anti-inflammatory materials. Additionally, the doctor may prescribe medicinal rinses, and in advanced cases, a course of antibiotics. - Third stage:
filling the canals and monitoring the results of treatment using radiography.
In particularly difficult cases, surgical intervention may be required to gain access to the affected root through an opening in the alveolar bone. If none of the treatment methods brings results, the tooth is removed.
Functions of periodontium –
- Retaining function - it consists in holding the tooth in the alveolus, and the dento-alveolar fibers of the periodontium are primarily responsible for this.
- Shock absorption and distribution function - intercellular substance and periodontal fibers allow you to evenly distribute the chewing load from the tooth to the alveolar tissue.
- Protective function - the connective tissue and cellular components of the periodontium represent the so-called “histohematic barrier”, which ensures the structural and antigenic homeostasis of both the periodontium itself and the surrounding tissues. The implementation of the protective function is mediated by both specific and nonspecific protective factors.
- Plastic function - ensures the preservation of the structure of the periodontium, as well as the reparation of both the periodontium itself and adjacent tissues (for example, the bone plate of the alveolus, as well as the cement of the tooth root). The periodontium is very rich in cellular elements, including osteoblasts, which are responsible for the formation of bone tissue on the surface of the alveoli, as well as cementoblasts, on which the production of replacement cement for the tooth root will depend.
- Trophic and sensory functions are provided by a well-developed vascular and nervous network (a large number of receptors). These functions are closely related to those listed above.
Lateral upper incisor
Average age of teething: 8-9 years
Average age of root formation: 11 years
Average length: 22.0 mm
The crown of the upper lateral incisor, approximating an oval shape, is almost ideal for endodontic access, as is the case with the central incisor. Fiber optic illumination is also helpful when accessing this tooth.
The initial opening using a fissure bur is made immediately above the enamel tubercle in the equatorial third on the palatal surface of the tooth. The access cavity is oval in shape. When performing the initial opening, the fissure bur often occupies the entire narrow cavity of the coronal pulp. After removing the roof of the pulp chamber, a ball-shaped bur No. 4 or 6 is used to clean it from carious dentin, pigmented areas and calcifications.
A fissure bur may again be required to finalize the oval shape of the access cavity.
Adequate expansion is then created using spherical burs. Care must be taken to ensure that probes, endodontic cutting instruments and condensation instruments do not come into contact with the walls of the access cavity.
To ensure the cleanliness of the canal walls and their hermetically sealed filling, all carious tissues and leaky fillings must be removed and replaced with temporary filling materials.
The cross-section of the canal varies from oval in the cervical part to round in the apical foramen. The root is slightly cone-shaped and can bend at the apical part, usually in a distal direction. The apical foramen is often located closer to the anatomical apex than the central incisor, but can be located laterally within 1-2 mm of it.
In rare cases, access is complicated by the presence of a “tooth-in-tooth” developmental anomaly, invagination of part of the lingual surface of the tooth into the crown. This creates a space in the tooth that is surrounded by enamel and communicates with the oral cavity. Tooth-in-tooth is most common in the upper lateral incisors, but can occur in other teeth. Due to anatomical developmental defects, these teeth are prone to caries and the pulp may die before the apex is fully formed. This formation (“tooth within a tooth”) is localized in the crown; it must be processed mechanically and removed or bypassed.
Complications after treatment of apical periodontitis
Treatment of acute apical periodontitis (as well as chronic) is a rather complex process that requires accuracy and concentration from the doctor. Like any intervention, it can lead to complications under unfavorable circumstances. What symptoms should you pay attention to after treatment of apical periodontitis?
- A sharp pain that occurs immediately after the end of the anesthesia may indicate that when filling the roots, the filling mass has gone beyond the boundaries of the tooth and is pressing on the gums. There is also a possibility of root perforation and breakage of the thin end of the endoscopic instrument in the root canal.
- After putting the medicine into the canals, the tooth hurts when pressed, and the gums are slightly swollen. These symptoms indicate that the doctor has used a strong medication that irritates periodontal tissue. It could also be a sign of an allergic reaction.
However, in most cases, timely treatment of apical periodontitis ends successfully and does not cause complications.
Apical periodontitis of the tooth - what is it?
The diagnosis of periodontitis is made when the patient's periodontal tissues near the apex of the tooth root become inflamed, which is why it is called apical. It affects deep gingival and bone structures, so it is not easy to treat - unlike, for example, caries. Nevertheless, this disease requires immediate intervention, because if the patient is not in a hurry to treat apical periodontitis, then he risks encountering unpleasant consequences of the disease: the appearance of granulomas and cysts, destruction of the alveolar bone, and in the most severe cases, even sepsis.
Diagnosis of apical periodontitis
It should be remembered that the symptoms of apical periodontitis are similar to the symptoms of some other oral diseases: pulpitis, sinusitis, hilar cyst and others. To make an accurate diagnosis, the following studies are necessary:
- electroodontometry
- helps to assess the degree of pulp necrosis; - radiography
- allows you to see tissue changes in the apical region; for chronic apical periodontitis, x-ray is the best diagnostic method, but it may not detect acute inflammation at an early stage; - A blood test
is an additional diagnostic method. With apical periodontitis, an increase in the level of leukocytes and ESR is observed.
The neck of the tooth is exposed, how to treat it
After the doctor has diagnosed the cause of the exposed cervix, he recommends the patient one of the following treatment methods:
- Filling the exposed area. This procedure is indicated at the initial stage of the pathological process. When a wedge-shaped defect has formed, there is nothing to attach the filling material to, so filling is irrelevant.
- Remineralization of enamel. A product containing calcium is used. The patient will not feel pain during the procedure. The process lasts about 10 minutes. A drug is applied to the affected tooth to help strengthen the enamel, protect the roots from exposure, and prevent tooth loss. In addition, the advantage of remineralization is the return of the enamel to its former shine. How many sessions a person needs is determined by the doctor.
- The enamel is coated with fluoride (fluoridation). Special varnishes or gels that contain fluoride are used. Fluoridation can be simple or deep. With the help of such methods, the dental neck is restored and tooth sensitivity is reduced. With deep fluoridation, the drug strengthens the enamel as it penetrates inside it.
- Installation of veneers. This is a thin ceramic plate. It is applied to a previously ground tooth. This technique is indicated for advanced cases. With the help of veneers, it is possible to completely eliminate the disease and minimize the risk of its recurrence.
- Crowns. Before installing crowns, the tooth is ground down. It is a radical way to protect the tooth root and prevent further progression of the pathology.
- Gum plastic surgery.
Drug and surgical treatment
If the cause of exposure of the neck of the tooth is a lesion or pathology of the mucous membrane, the patient is consulted by an implant surgeon. During the operation, tissue taken from the palate of the mouth is implanted under the tooth root. This helps to increase the volume of gum tissue and cover exposed areas of the tooth. At the end of the surgical intervention, sutures are placed on the gums. After this, the patient is scheduled to regularly visit the attending physician, who will monitor the healing process.
Use an antiseptic solution to rinse your mouth. You can eliminate swelling and redness of the gums with the help of medicinal gels. If pus is present, an antibacterial drug is prescribed. The choice of medication is made only by the attending physician; self-medication is prohibited.
Upper first premolar
Average age of teething: 10-11 years
Average age of root formation: 12-13 years
Average length: 20.6 mm
The first upper premolar is a transitional tooth between the incisor and molar and most often has two roots.
When molars are lost, the main chewing load falls on the premolars. In removable prosthetics, these teeth are used as supporting teeth, which increases the impact of torque on them. Additional torque forces, together with deep carious lesions, can cause severe calcification of the pulp cavity. Early molar loss often causes rotation of the premolars, which can make identification of the pulp chamber difficult.
The mouths of the canals are located below and somewhat to the center of the tops of the mounds. The initial opening is made in the central fissure, giving it an oval shape in the bucco-palatal direction. After identifying the mouth, the doctor must accurately determine the presence of an anastomosis leading to the mouth of another canal. The direction of the roots can be determined using an endodontic probe. Root bifurcation visible on a routine periapical photograph may indicate tooth rotation. With divergent roots, less expansion of the occlusal approach is required, and with parallel roots, on the contrary, it may be necessary to remove the crown tissue towards the tops of the cusps. All infected dentin and leaking fillings should be removed and replaced with suitable temporary fillings.
Options for root anatomy include fused roots with separate canals, interconnecting canals or a “web,” a common apical foramen, and the possible presence of three roots, which is rare but should always be kept in mind. In the latter case, the mouths of the buccal canals will not be clearly visible using a dental mirror. An endodontic probe or a thin file will help determine the structure of the canal. Cams and Skidmore report that maxillary premolars with three roots and three apical foramina are found in 6% of cases. The length of the root is much shorter than that of the canine, and a distal bend is not common. The apical foramen is usually located close to the anatomical apex. The length of the roots when using intact tubercles as reference points is usually the same. The apical part of the roots often tapers sharply, ending in very narrow and curved tips.
Given the possibility of vertical mesial-distal fractures of the crown or root of the first premolar, before endodontic treatment, all fillings should be removed and the crown should be carefully examined under fiber light.
To prevent vertical fractures of the crown or root after endodontic treatment, it is necessary to completely close the occlusal access cavity.
Upper first molar
Average age of teething: 6-7 years
Average age of root formation: 9-10 years
Average length: 20.8 mm
The largest in size, with a complex anatomy of the root and root canal system, the so-called “6-year molar” is the most frequently treated, while presenting the greatest difficulties in treatment among the posterior teeth. During its treatment, the largest number of endodontic errors and complications arise, and it is undoubtedly one of the functionally important teeth.
The three separate roots of the maxillary first molar form a trifurcation: the palatal root is the longest, and the distal buccal and mesiobuccal roots are approximately the same length.
The palatal root in the apical third often curves in a buccal direction. Of the three channels, it has the largest diameter and is the easiest to access. Its mouth is shifted to the palatal wall of the crown. The root deviates sharply from the median axis of the tooth. In cross section, the root is flattened and has a ribbon-like shape, which requires special attention when cleaning and instrumenting it. Fortunately, it rarely has more than one apical foramen.
The distal buccal root is conical and usually straight. It always has one channel.
The mesiobuccal root of the first molar has generated more research, clinical inquiry, and frustration than any other root in the oral cavity. Green showed that 14% of the mesiobuccal roots of the maxillary first molars studied had two apical foramina, and 36% of the roots had two orifices. Pineda reported that 42% of these roots had two canals and two apical foramina. Slowey confirmed Pineda's data within a few percent difference. The fact that nearly half of these roots have two canals, whether they end in a single opening or not, is reason enough to always assume two canals until careful examination proves otherwise.
The additional orifice lies centrally, between the orifices of the mesiobuccal and palatine canals. The search is facilitated by using fiber optics and by identifying the anastomosis between the orifices of the mesiobuccal and palatal canals. The second canal in the mesiobuccal root will always be narrower than the other canals, so it is more difficult to clean and shape. Access to the main mesiobuccal root canal is easier when a straight entry is properly created.
All carious tissue, leaking fillings and denticles must be removed before endodontic treatment begins.
After treatment, complete closure of the approach is necessary to prevent vertical coronal or crown-root fractures. If indicated, internal reinforcement with intraradicular pins is recommended.
