The dental pathology we face in the group of premolars is related to: dental caries, dental trauma (crown fractures and also frequent crown-root fractures), and dental wear phenomena. Dental caries are frequently encountered in premolars and often lead to their absence from the arcade in young adults. The crown or crown-root fractures may be the result of several factors: the evolution in depth and surface of some carious processes, the use of the premolars by the patient during vicious habits, the occlusal morphology (especially the maxillary premolars). Dental wear phenomena are common in premolars: abfraction lesions, cervical abrasion lesions, or abrasion of the occlusal cusps.
Patologia dentară cu care ne confruntăm în cadrul grupului premolarilor este legată de: afectarea prin procese carioase, traumatisme dentare (frecvente fracturi corono-radiculare), fenomene de uzură dentară. Procesele carioase sunt frecvent întâlnite la premolari și conduc de multe ori la absența lor de pe arcadă, la vârsta adultului tânăr. Fracturile coronare sau corono-radiculare pot fi consecința mai multor factori: evoluția în profunzime și suprafață a unor procese carioase, utilizarea acestor premolari de către pacient în timpul unor obiceiuri vicioase, morfolgia coronară cu cuspizi foarte accentuați (premolarii maxilari). Fenomenele de uzură dentară sunt frecvent întâlnite la premolari: leziuni de abfracție, leziuni cervicale abrazive, abraziunea cuspizilor de sprijin.
Premolars are part of the group of definitive lateral teeth. They are located distally after the canines, and there are two premolars on each arch: the premolar prim and the second premolar, altogether eight teeth. Unlike the molars, which erupt on the dental arch without replacing a temporary tooth, the premolars replace the deciduous molars on the child’s arcade.
Premolars are the only teeth with different periods of eruption depending on sex, namely:
In boys: upper first premolar to 9-10 years.
In girls: upper first premolar to 10-11 years.
In both sexes: first premolar lower to 10-12 years.
In both sexes: second premolar lower at 11-12 years.
In both genders: second upper premolar at 10-12 years.
Premolars are monoradicular teeth, with the exception of the upper first premolar, which has two roots, therefore implantation is less than that of the molars.
The premolars functions are:
Masticatory function - the most important.
The masticatory function
The masticatory function of premolars is given by their position, being transitional teeth located between the canine and molar teeth. Also, their occlusal surface relief, especially of the superior premolars, makes them playing an important role in the fragmentation and trituration of the food. Premolars function is for tearing and grinding food during chewing.
The aesthetic function
Although the location of the premolars is in the lateral area of the jaw arches, they also play an important role in the aestehics, especially the upper ones. Both first and second premollars are extremely visible during smile, laughing and speech. Any damage or absence of upper premolars from the dental arches is highly visible due to their position immediately after the canine and their quasi-permanent exposure.
The upper premolars have an important role to play also: to support the soft tissues and cheeks, thus contributing to the aesthetic appearance of the person. Lower premolars have a more limited role in aesthetics than the maxillary ones. Only the buccal and occlusal surface are more or less visible depending on the patient.
The phonetic function
The phonetic function is related especially to the maxillary first premolars, that participate in the phonetic articulation together with the upper front teeth. Teeth help us pronounce accurately as they have an important role in the pronunciation of consonants. In the absence of frontal premolars upper teeth, the normal speech can be severally affected.
Another important function of the premolars is that they play a role in stabilizing the occlusion through occlusal stops and maintaining the vertical occlusion dimension.
The coronal pathology
The coronal pathology we face in the group of premolars is related to:
dental trauma (crown fractures and also frequent crown-root fractures);
dental wear phenomena (abfraction lesions and abrasive cervical lesions due to intensive dental brushing).
I. The dental caries located on the premolars are consequences mainly of the occlusal morphology, which favors the retention of dental plaque, as well as the localization of the teeth in the lateral area of the dental arches.
In addition, children’s lack of interest in a correct and complete dental hygiene at 10-12 years, when these teeth erupt, makes them vulnerable to caries. By their evolution, carious processes determine in many clinical cases pulp complications (acute inflammation: partial or total pulpitis) or mechanical complications, which are very common.
Dental caries are frequently encountered in premolars and often lead to their absence from the arcade in young adults. Usually, the maxillary premolars are more affected than the lower ones.
II. The crown or crown-root fractures may be the result of several factors:
the evolution in depth and surface of some carious processes that undermine the resistance of the cusps;
the use of these premolars by the patient during vicious habits (holding a writing instrument, pipe holding, opening of the bottle caps etc.). The upper premolars are especially affected by these parafunctions. It should be also noted that bruxism can cause the fractures of premolars’ cusps, especially when these teeth have been previously affected by coronal tissues loss or incorrect restorations;
the massive crown restorations can jeopardize the integrity of the premolar coronal walls, due to the composite contraction during polymerization and consequently the flexion of the cusps;
the association with dental wear phenomena (the presence of cervical lesions increases the susceptibility to premolar fracture);
the upper premolars present a special occlusal morphology: two very active and sharp cusps, separated by a deep central mesio-distal groove. The buccal cusp is very sharp and with a low volume, therefore it is extremely vulnerable to fractures. This kind of trauma can occur when axial forces of high intensity are applied (for example, a strong hit which determined a sudden and violent occlusion of dental arches). The more rounded relief of the lower premolars makes them more resistant to such accidents.
III. Dental wear phenomena are common in premolars, whether we talk about abfraction lesions, cervical abrasion lesions, or abrasion of the occlusal cusps: especially the oral cusps in the upper premolars, or active vestibular cusps in the lower premolars.
Abfraction lesions or stress lesionsoften occur in premolars. They appear as a result of exerting excessive loading forces. These eccentric forces determine the breaking of the enamel rods in the cervical area, thus creating a V-shape cavity at this level. The etiopathogenesis of abrasion lesions is clearly of occlusal nature, and it is proved that bruxism or other parafunctions are associated with the triggering of this type of cervical lesion. Abrasion lesions appear primarily in the anterior area of the dental arches, including the premolar area.
Dental abrasion lesions. One of the most common types of dental abrasion in premolars is the one situated in the buccal cervical region. The main etiological factor is the incorrect tooth brushing and its clinical aspect is: hard tissues erosions, with a smooth, polished appearance.
The lesions are more extensive in the surface than in the depths, and occur mainly in areas accessible to the toothbrush: the frontal area and the premolars. Most of the times, the cervical abrasive dental erosions are accompanied by the adjacent gingival inflammation. Cervical abrasion lesions often appear on the left dental arch, especially in the upper premolars, in right-handed persons, and on right side of the left-handed persons. In general, the upper premolar region is the first area where the toothbrush is inserted and where vigorous horizontal scrubbing actions are made. Cervical lesions, regardless of their etiology, represent an additional stress factor for the premolars and contribute to the occurrence of coronary fractures, especially for the maxillary premolars.
The phenomenon of occlusal surfaces wear is frequently encountered in patients who have parafunctions. The excessive forces that occur during these parafunctions can produce the fracture of the cusps or of the thin and fragile crown walls.
The pulp and periapical complications as a result of the carious processes, the traumas and the phenomenon of dental wear in premolars are very common. Many young adult patients refer to the dental office for a dental pathology associated with the premolar group and require direct restaurations, prosthetic restorations or endodontic treatment in premolars. Last but not least, the high frequency of the premolar extraction in young age has to be mentioned.
Acknowledgement: For this article all the authors have equal contributions.
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