The upper pre-molars accounted for 70.2% of all pre-molars extracted due to caries, compared to 29.8% of lower pre-molars. It has similarly been reported that maxillary second pre-molars were more commonly extracted in Singapore as a result of caries and its sequalae.¹¹ The reasons for the difference in the rate of extraction due to caries and its sequalae may partly rest on the morphological differences, as the upper pre-molars have well defined palatal cusps and therefore deeper pits and fissures. It may also be as a result of poor saliva distribution in and around the upper pre-molar region as the buffer and cleansing action of the saliva may be reduced in this areas.

In this study it was observed that the mandibular molars accounted for 65.1% of all molar extraction due to caries, compared to 34.9% of maxillary molars. In the Singapore study, 63.7% mandibular first molars were extracted due to caries as against 44.7% of maxillary first molars¹¹. The reason may largely be due to morphological differences since, the mandibular molars have more extensive pits and fissures present in them while the fissures of maxillary molars are limited by the presence of oblique ridge. The direct secretions from the parotid gland duct, which is buccal to the maxillary teeth, may also assist in reducing the pH around the maxillary molars. In this study the first molar accounted for 50.9% of all molar extractions due to caries irrespective of quadrant. A related study in Ile- Ife reported 41.6%¹ and West Indies 45.3%⁷. It may be argued that the time of eruption may largely be responsible; at age six, the child may not have imbibed the various methods of maintaining good oral health, and also lacks the dexterity necessary in the use of both toothbrush and chewing sticks. A related study in Glamorgan noted that more decayed or filled occlusal surface were present in the second molars and pre-molars of those quadrants and arch, which have lost their first molar¹². They extrapolated from the result of the study that whatever aetiological factors were operating to place the child in high-risk group early in life continues to operate in the early teenage years¹². It was observed that the maxillary second molar was the least extracted due to caries. The reason may be due to the opening of the Stenson’s duct (parotid gland duct), which helps to buffer and cleanse bacterial plaque products.

CONCLUSION

The morphology, time of eruption and position of each tooth type confers an inherent advantage/disadvantage to the various methods employed in plaque control and to naturally occurring defense factors. The result of this study showed that teeth with deep pits and fissure like the maxillary premolars and molars are most susceptible to dental caries and would benefit from the use of prophylactic pits and fissure sealants.

This work was supported by a research grant from the Regional Centre for Oral Health Research and Training Initiatives (RCORTI) for Africa in Collaborative with WHO. Our thanks go to the entire staff of Plateau State Government Dental Centre for their assistance during the period of data collection.