Research histological, physiological, and anatomical features of the primary dentition. The student should delve into the background of different nationalities to see any difference in anatomical characteristics. Anything of interest or anomalies should be reported.

Introduction

Located in the oral cavity and at the angle of the dental arch, there are 4 canines, distributed as follows: two upper canines, located on either side of the upper incisors. Two lower canines, located on either side of the lower incisors. This dentition is what is referred as primary dentition. However, traditionally, there have been various histological, physiological, and anatomical features of primary dentition. In this paper a review is completed on several background of difference nationalities to establish variation in anatomical characteristics of primary dentition.

Difference in anatomical characteristics for primary dentition

Scholars from different countries have provided difference anatomical characteristics of primary dentition. In particular, pertaining earlier development of the primary teeth in relation to deciduous molar. For instance, Otuyemi et al. (1997) claimed that in case the malocclusion are found in the primary dentition, similar occlusal problems would be anticipated to occur in the subsequent permanent dentition in a study conducted in Africa. This perhaps in an anatomical anomaly for the feature of the primary dentition. However, data from American scholars such as observed that malocclusion varies significantly with age and population global (Bhat et al., 2012). This make the physiological characteristics of primary dentition to be complex.

The spacing and size of molar has been proved to differ based on population. A study performed in India found that the flush terminal molar was positioned between 67.7% on the right and 68.1% on the left which is similar to (Alexander & Prabhu, 1998). Though, another study performed in the US as well as in India found that the flush terminal place of the molar to be 72% (Nanda & Anand, 1973). Bhat et al. (2012) observed that the variation in primary dentition are because of changes to the forward development of the mandible. However, Farsi et al. (1996) found different molar occlusion spacing (71%) in a study conducted in Saudi Arabia. Besides, the study unlike Bhat et al., which related the difference to growth of mandible, Farsi et al. (1996) related the variation to the invariable maintained throughout the primary dentition stage and is usually converted unchanged to the permanent dentition.

Regarding the prevalence of canine class II association, Bhat et al. (2012) from the US found the canine of the children to be 7.2% which is smaller than 45% in a study done in the UK. Further, the overbite variation between different scholars have been observed. For

example, Bhat et al. (2012) found the overbite size to be 1.9mm and the prevalence of overjet to be more than 2mm. Though, these overbite and overjet sizes were different from Foster (1969) and Farsi (1996) which was 3mm and 2.5m respectively for overbite and 2.4mm for overjet.

There are evident occlusal anomaly across the globe where the frequency of 0.6% in Nigerian population, which differs with that one of 0.5% in Australian, The infra-occlusion was found in studies done in many Israeli children that is prevalence of 24.8% was observed. This was different from the prevalence of 6.9% in North American and Whites of Scandinavian descent. The occurrence of 8.9% was observed in Swedish children and 2.5% in British children (Kurol, 1981). It was nevertheless argued that the muscle trajectory was not physiological because the Myomonitor stimulated synchronously the elevator muscles and depressants (which does not normally occur) and that this stimulation could lead to a resting position and a path of exhaustion.

Discussion

It is not possible to conclude, based on the amplitude of the electromyogram that the resting position of the mandible depends on muscle relaxation or fatigue. It has been argued that trigeminal teeth do not necessarily immediately correct neck posture, which can overload the chewing muscles and thus cause their exhaustion by simultaneously cutting off the blood supply to the elongated and contracted muscles. But Bhat et al. (2012) demonstrated by analyzing the frequency of EMGs that molars actually relaxes the muscles of the mandible. These latest studies also demonstrate that the absence of fatigue stemmed from the fact that motor neurons are refractory to any proprioceptive impulse and that it was therefore possible to use them to distinguish orthogonal (standing) posture from non-orthogonal posture. On the other hand, the de-programmers of the occlusion.

In young children chewing movements do not develop until after the arrival of the teeth. The mandibular and occipital condyles develop simultaneously and are identical in shape. The antero-posterior movements of the head occur at the level of the joint of the occipital bone and the atlas while the atlas or axis joint allows the rotation of the head and the mandible around the odontoid process of the ‘axis. The odontoid process is the body of the atlas and originates from the body of the axis. Neuromuscular or myocentric occlusion is defined as the maximum balanced, stress-free contact position of the teeth. The plane connecting the base of the occipital condyle, the base of the maxilla at the level of the

hamular notches and the incisal canal constitutes an important bone reference in occlusion reconstruction. These points being covered with a comparable thickness of mucosa and periosteum are therefore useful in mounting the maxillary models on the articulator according to the HIP plane. The HIP plane is used in prosthetic and occlusal reconstructions as well as in aesthetic rehabilitations.

It is interesting to note that all the vertebrae except the atlas have a tripod support. For the atlas, the anterior support is provided by the occlusion which, when deficient, leads to collapse of the upper cervical complex. Studies such as (Bhat et al. (2012) and Otuyemi et al. (1997) have designated this descending primary dentition anomaly to an abnormal occlusion resulting from an abnormal body posture which also affects the alignment of the atlas and the axis. Either way, the physiology of the whole organism will be affected (Bhat et al., 2012).

Conclusion

The anomaly of the primary dentition or occlusion and occlusal dysfunction is characterized by a conflictual confrontation of the dental arches favoring structural alterations of the constituent elements of the manducator apparatus and an adaptive behavior disrupting an ergonomic management. Among the occlusal dysfunctions, a distinction is made between timing anomalies, centering anomalies and guidance anomalies. From the research and literature review, it is evident that racial factors play a critical role in the variation of primary dentition and emergence of submerged teeth. For instance, while twelve scissors bite was not found in any of the research connected by that et al. (2012) studied unlike Kurol (1981) who found more scissors. This occlusal anomaly is described in few epidemiological research. Equally, no cases were observed in Saudi children in studies done by Farsi et al. (1996).

References

Alexander, S., & Prabhu, N. T. (1998). Profiles, occlusal plane relationships and spacing of teeth in the dentitions of 3 to 4 year old children. The Journal of clinical pediatric dentistry, 22(4), 329-334.

Bhat, S. S., Rao, H. A., Hegde, K. S., & Kumar, B. K. (2012). Characteristics of primary dentition occlusion in preschool children: An epidemiological study. International Journal of Clinical Pediatric Dentistry, 5(2), 93.

Farsi, N. M., & Salama, F. S. (1996). Characteristics of primary dentition occlusion in a group of Saudi children. International journal of paediatric dentistry, 6(4), 253-259.

Foster, T. D. (1969). Occlusion in the primary dentition Study of children at 2 1/2 to 3 years of age. Brit. dent. J., 126, 76-79.

Kurol, J. (1981). Infraocclusion of primary molars: an epidemiologic and familial study. Community dentistry and oral epidemiology, 9(2), 94-102.

Nanda, R. S., Khan, I., & Anand, R. (1973). Age changes in the occlusal pattern of deciduous dentition. Journal of Dental Research, 52(2), 221-224.

Otuyemi, O. D., Sote, E. O., Isiekwe, M. C., & Jones, S. P. (1997). Occlusal relationships and spacing or crowding of teeth in the dentitions of 3–4‐year‐old Nigerian children. International journal of paediatric dentistry, 7(3), 155-160.