Ten reasons to not ignore the third molar

ABSTRACT Introduction: The third molars are forgotten because they are the last in the dental arch, they do not directly influence the smile and they appear only in adolescence, when they do. Objectives: 1) to provide the clinician with a “checklist” to assess and diagnose changes to be screened in the third molar region in new patients; 2) to reveal the importance of not discharging the patient submitted to any dental treatment without first analyzing the third molars region clinically and on imaging examinations, since many diseases are associated to them. Result: A list of 10 situations that cover all diagnostic possibilities involving the third molars is presented. Conclusion: Adopting this protocol is a matter of habit, since the need is fundamental. The next professional assisting your patient may ask: “Did he not request examinations for the third molars?”.


INTRODUCTION
It is not uncommon for us to examine only the tooth related to the main complaint of the patient, such as painful sensitivity, gingival recession and/or an esthetic change, or even an enamel fracture and/or a poorly fitting restoration.
It is also not uncommon to focus only on the expectation due to which the patient sought the professional, such as whitening, a facet, dental alignment or restoration.
Unfortunately, many patients finish their orthodontic treatments, even with orthognathic surgeries, with upper and/or lower third molars with anomalies of position and eruption, inducing resorptions in neighboring teeth, with pericoronitis and paradental cysts.
Ideally, after the first consultation, we should request a panoramic radiograph and periapical radiographs of the jaws. The surprise will always be present, as dental anomalies, periapical lesions, tooth resorptions, intraosseous lesions, calcific metamorphoses of the pulp, supernumerary teeth, unerupted teeth, etc.
With the images and an imaging report in hand, you will feel a complete professional in planning, and the patient will feel much reassured about the professional caring for his or her oral health. This routine will make you a happier professional! In the third molar region, embryonic odontogenic tissues are exposed for many years to intrinsic and extrinsic environmental factors, as well as growth and lack of space, which combine and increase the possibility of problems related to anomalies of shape, position and eruption. This region should be checked for each new patient to prevent resorption, pericoronitis, paradental cysts, concrescences, cysts and odontogenic tumors.
Thus, pain and mutilation are avoided, and the patient will always be close to the desired function and esthetics.
The aim of this work is to provide the clinician with a "checklist" or a protocol to assess and diagnose changes to be screened in new patients, regarding the third molar region. The other objective is to reveal the importance of not discharging the patient submitted to any dental treatment, including orthodontic treatment, before analyzing the third molars region clinically and by imaging examinations.

IN ALL DENTAL PATIENTS, INCLUDING ORTHODONTIC PATIENTS
Ask yourself and your patient: where and how are the third molars. They can be: Consolaro A, Hadaya O -Ten reasons to not ignore the third molar

Erupted and in normal occlusion with the antagonist,
which is ideal and desired, yet unfortunately it does not always happen (Fig 1). If the antagonist is not present, its tendency is to extrude and cause periodontal and sensitivity problems.

Erupted and in normal occlusion with the antagonist, yet
without distal bone space to form a healthy gingiva (Fig 1).
The gingiva may be occupying the entire distal aspect of the      chronic pericoronaritis alternately to give rise to a paradental cyst on its distal or mesial aspect towards the mandibular base (Figs 7 and 8). 1,2,3,4 On the face opposite to that occupied by the cyst, the gingival tissues may be normal.  : Paradental cysts from normal pericoronal space to the development on the mesial surface of the partially erupted lower third molars, mesially angulated and horizontalized on the right side of the panoramic radiographs. It is noteworthy that the patient in C was discharged from previous orthodontic treatment and was also affected on the left side.

Partially erupted and impacted on the second molars,
with Inflammatory external root resorption due to the pericoronal follicular tissues in contact and interacting with the gingival and ligament tissues (Fig 9). 5,6 There will be compression of vessels, eliminating the cementoblasts from the root surface and initiating an inflammatory external root resorption on the distal surface of lower (Fig 10) and upper second molars (Fig 11). The partially erupted third molar with its pericoronal follicular tissues, combined to the force of the eruption pathway, can compress the vessels due to lack of oxygenation and eliminate the cementoblasts on the root of the associated lower second molars, thus initiating an external inflammatory resorption process (arrows).

Partially erupted, mesially angulated and impacted on
the second molars, with inflammatory external cervical resorption from the cementoenamel junction of these teeth (Fig 12). The pericoronal follicles and associated inflammation digest the extracellular connective tissue matrix that hid the dentin in exposed micro-windows. The exposed dentin tends to be resorbed because it stimulates the immune system, since it has six proteins recognized as foreign by our body. 5,6 Figure 12: External cervical resorption in the second molar associated with exposure of the cementoenamel junction to follicular tissues of the partially erupted third molar (3D reconstruction in B and C and coronal sections in D).

Unerupted, without impaction on neighboring teeth,
which occurs due to lack of bone space in the alveolar process. They are asymptomatic and are not even noticed by the patient, but due to their position they end up impacting the second molars over time or remain indefinitely unerupted.
Without a minimum masticatory function, the periodontal ligament becomes markedly atrophic over time and the teeth may eventually become ankylosed and undergo replacement tooth resorption, disappearing completely. 5,8,9 In some occasional cases, the lack of eruption and without impaction, especially in upper third molars, the excessive proximity to the periodontal ligaments, being one of them without minimum masticatory function, can lead to concrescence 10 with the second molar (Fig 13).

Unerupted without impaction on neighboring teeth,
with dentigerous cyst. This situation is occasional and occurs due to accumulation of fluid between the reduced enamel epithelium and the dental enamel (Fig 14). Supposedly the dentigerous cyst occurs due to venous compression in the eruptive movement, yet this is still only a theory to explain its mecha- induced by previous acute and chronic pericoronaritis, i.e., it has another mechanism of formation. 3,4,6 The pericoronal follicle has a thickness of up to 5.6 mm; above this, it should be considered a dentigerous cyst. Due to image distortion, this measure can make the case in a borderline situation. The greater the thickness of the follicular space, the more likely it is to be a dentigerous cyst. This situation is defined by the outflow of liquid between the follicle and enamel during transoperative surgical procedures. In these cases, it is also microscopically difficult to distinguish a pericoronal follicle from a dentigerous cyst. 1,2,3,4,6 Consolaro A, Hadaya O -Ten reasons to not ignore the third molar Figure 14: Dentigerous cysts: from normal pericoronal space to a gradual increase in thickness, causing the cystic cavity (arrows) by a process resulting from the eruptive process without microbial contamination, collecting liquid between the pericoronal follicular epithelium and enamel, without inflammatory process. In B, the patient who was discharged from orthodontic treatment is highlighted. 9. Unerupted, without impaction on neighboring teeth, with odontogenic keratocyst. Up to 30 years of age, the pericoronal follicle is rich in odontogenic epithelium islets derived from the dental lamina, which can give rise to odontogenic keratocyst. When developing in the pericoronal follicle, the odontogenic keratocyst will present the imaging and clinical aspect of dentigerous cyst for a long time (Fig 15). In most

FINAL CONSIDERATIONS
A dental patient should not be discharged without being sure that he or she does not have a disease in the jaws. For this reason, in any planning, even for a simple restoration, it is important to have panoramic and periapical radiographs of the jaws in hands.
Unfortunately, many patients finish their treatments and are Working on dental crowns requires knowledge on how the periodontium and underlying bone are, always thinking about the patient as a whole also over time. The diseases, even the most serious, start small and with asymptomatic signs. The early diagnosis can prevent further damage and functional and structural mutilation.