**2. Impacted teeth**

The reasons for tooth impaction might include a several factors such as position and size of adjacent teeth, dense overlying bone, excessive soft tissue or a genetic abnormality including abnormal eruption path, dental arch length and space in which to erupt (Jojic & Perović, 1990; Alling et al., 1993; Hupp et al., 2008). Generally speaking these factors are subdivided into a two groups as local and general factors. The most common impacted teeth are mandibular and maxillary third molars, followed by the maxillary canines and mandibular premolars (Jojic & Perović, 1990; Hupp et al., 2008). Third molars have inadequate space for eruption, thus they are the last teeth to erupt. New data suggests that 72,7% of the world population has at least one impacted tooth (usually lower third molar), and it is more frequently in female than the male patients (Ahlqwist & Grondahl, 1991; Alling et al., 1993,).

Although indications for removal of impacted teeth vary from orthodontics, prosthodontics, pathologic and prophylactic, one of the reasons that impacted teeth should be removed, is their influence on the adjacent teeth with development of the caries lesions.

Caries is mentioned as one of the common pathological features associated with extracted mandibular third molars (Battaineh et al.,2002; Lysell & Rohlin, 1988; Punwutikom et al., 1999). This is a reason why in this section the emphasis will be on these teeth.

There is an opinion that the tooth position and inclination play a main roles in caries development process (Knutsson et al.,1996). For better understanding this relationship it is necessary to know a classification of impacted lower third molars. The most common used classification is by Winter in which third molars are classificated by their long axis angulation with respect to the long axis of adjacent second molars. Mesioangular position is the most seen type of third molar impaction comprising 43% of all third molar impactions, characterized by mesial direction of the third molar's long axis toward to the second molar with convergency angle of >30 (Kan et al., 2002). In vertical position, the long axis of impacted tooth runs parallel to the long axis of the second molar comprising 38%. Distoangular position including 6% of the cases is characterized by distally or posteriorly angled long axis of the tooth away from the second molar. If the long axis of the impacted tooth is perpendicular to the second molar comprising 3% of all cases, this position is known as the horizontal (Kan et al., 2002; Hupp et al., 2008). However, atypic positions in which impacted teeth are angled in buccal, linqual, palatal or buccolinqual directions are also recorded (Jojic & Perović, 1990; Hupp et al,. 2008). .

The second also in use classification is by Pell and Gregory, in which are described three positions of the third molars: depending of the relation of tooth to ramus and second molar subtypes (Type A), relative depth of the third molar in bone (Type B) tooth on same level with occlusal plane and position of long axis of the impacted tooth in relation to the second molar as taken from the Winter classification (Type C). (Kan et al., 2002; Hupp et al., 2008).

than Blacks (Brown et al., 1982), and females are more predisposed to this phenomenon than males (Jojic & Perović, 1990). However, by Haidar and Schalhoub (1986) in Saudi population, especially in cases of impacted third molars, male are more prone to have an

The reasons for tooth impaction might include a several factors such as position and size of adjacent teeth, dense overlying bone, excessive soft tissue or a genetic abnormality including abnormal eruption path, dental arch length and space in which to erupt (Jojic & Perović, 1990; Alling et al., 1993; Hupp et al., 2008). Generally speaking these factors are subdivided into a two groups as local and general factors. The most common impacted teeth are mandibular and maxillary third molars, followed by the maxillary canines and mandibular premolars (Jojic & Perović, 1990; Hupp et al., 2008). Third molars have inadequate space for eruption, thus they are the last teeth to erupt. New data suggests that 72,7% of the world population has at least one impacted tooth (usually lower third molar), and it is more frequently in female than the male patients (Ahlqwist & Grondahl,

Although indications for removal of impacted teeth vary from orthodontics, prosthodontics, pathologic and prophylactic, one of the reasons that impacted teeth should be removed, is

Caries is mentioned as one of the common pathological features associated with extracted mandibular third molars (Battaineh et al.,2002; Lysell & Rohlin, 1988; Punwutikom et al.,

There is an opinion that the tooth position and inclination play a main roles in caries development process (Knutsson et al.,1996). For better understanding this relationship it is necessary to know a classification of impacted lower third molars. The most common used classification is by Winter in which third molars are classificated by their long axis angulation with respect to the long axis of adjacent second molars. Mesioangular position is the most seen type of third molar impaction comprising 43% of all third molar impactions, characterized by mesial direction of the third molar's long axis toward to the second molar with convergency angle of >30 (Kan et al., 2002). In vertical position, the long axis of impacted tooth runs parallel to the long axis of the second molar comprising 38%. Distoangular position including 6% of the cases is characterized by distally or posteriorly angled long axis of the tooth away from the second molar. If the long axis of the impacted tooth is perpendicular to the second molar comprising 3% of all cases, this position is known as the horizontal (Kan et al., 2002; Hupp et al., 2008). However, atypic positions in which impacted teeth are angled in buccal, linqual, palatal or buccolinqual directions are also

The second also in use classification is by Pell and Gregory, in which are described three positions of the third molars: depending of the relation of tooth to ramus and second molar subtypes (Type A), relative depth of the third molar in bone (Type B) tooth on same level with occlusal plane and position of long axis of the impacted tooth in relation to the second molar as taken from the Winter classification (Type C). (Kan et al., 2002; Hupp et al., 2008).

their influence on the adjacent teeth with development of the caries lesions.

1999). This is a reason why in this section the emphasis will be on these teeth.

recorded (Jojic & Perović, 1990; Hupp et al,. 2008). .

impacted teeth than female patients.

**2. Impacted teeth** 

1991; Alling et al., 1993,).

The practice suggests that horizontal and mesioangular positions are more critical to adjacent second molar, because impacted teeth in these positions may impige and resorb a distal surface and root of the second molars (Knutsson et al.,1996).

#### **2.1 Winter classification of impacted lower third molars**

Fig. 1. Mesioangular position of the lower third molar.

Fig. 2. Lower third molar in vertical position.

Impacted Teeth and Their Influence on the Caries Lesion Development 67

The most common causes of the tooth lost are caries and periodontal disease, following a tooth fracture (Jacobsen, 2008). Data suggests that in most industrialized countries 60-90 % of school aged children and almost 100% of adult population are affected by tooth decay (Petersen et al., 2005), with the prevalence, which is more higher in female than male

Tooth decay or dental caries is defined as chronic, multifactoral disease characterised by localized destruction of hard tooth tissues. It attacks on the mineralized tissues resulting in demineralization and in some cases destruction of the matrix (Jacobsen, 2008) . By some authors dental caries starts as small subclinical demineralised subsurface, which following a periods of remineralization and demineralization, may progress or arrest (Walmsley et al., 2002). There is an opinion that approximatelly 50 different factors subdivided into a three groups are in correlation with caries etiology: The first group is formed of those factors associated with the host such as quality of saliva and bacterial flora (Streptococcus mutans, Streptococcus sanquis, Actinomyces and Lactobacillae are the most commonly isolated from the caries lesions. These microorganisms produce lactic acid, also known as the milk acid, responsible for the caries development). The second group includes outside factors such as diet and the substrate on which bacteria act, while the third group content a tooth itself and

those features which either predispose to or resist carious attack (Jacobsen, 2008).

Caries can affect enamel, dentin and cement, with usually localization at the cementoenamel junction or in the cementum. However, in modern men grooves and fissure areas of the posterior teeth are the most common sites of decay (Newbrun,1989; Fejerskov & Kidd, 2008). There is a relationship between debth of the fissures and caries susceptibility, due to fact that food debris and microorganisms impact in the fissures. This leads to conclusion

Fig. 5. Atipic position of the impacted tooth.

(Lukacs & Largaespada, 2006; Ferraro & Vieira, 2010).

**3. Caries** 

Fig. 3. Horizontal position of lower third molar.

Fig. 4. Distoangular position of lower third molar.

Fig. 5. Atipic position of the impacted tooth.
