A survey of approximal root concavities in an ethnic Chinese population

A cone-beam computed tomography study of the mesial cervical concavity of maxillary first premolars

OBJECTIVE

To investigate the mesial cervical concavity of maxillary first premolars and its relationship with root and canal configuration using cone-beam computed tomography (CBCT).

DESIGN

Images of maxillary first premolars (n = 1056) were collected from patients (n = 601) who had undergonein vivo CBCT scanning. The root and canal number and morphology were evaluated. The following measurements of the mesial cervical concavity of the maxillary first premolars were evaluated in section images: dentine thickness (in concavity at the cemento-enamel junction), concavity angle, depression depth (distance from mesial dentinal surface at concavity to mesial proximity), concavity position (distance from mesial dentinal wall at invagination to the top of the mesial marginal ridge). The reliability of the data was analyzed with an unpaired Student's t test and Fisher's exact test.

RESULTS

The percentages of maxillary first premolars with one root, two, and three roots were 55.5%, 43.7%, and 0.8% respectively. Mesial cervical concavity was recorded in 64.5% of single-root maxillary premolars. The prevalence of two-root maxillary first premolars with mesial cervical concavity was 73.8%. The means of the aforementioned four measurements were 1.705, 147.9, 1.640, and 5.247 mm. The values of dentine thickness (mm), depression depth (mm), and concavity position (mm) of the mesial cervical concavity were largest in two-root maxillary first premolars. The smallest concavity angle of the mesial cervical concavity was found in three-root maxillary first premolars.

CONCLUSIONS

There is a high prevalence of mesial cervical concavity among maxillary first premolars. The mesial root concavity is more prevalent in single-rooted maxillary first premolars when there are two canals present, and its prevalence and degree of concavity increase with the number of roots.

The relationship between root concavities in first premolars and chronic periodontitis

OBJECTIVE

To evaluate the significance of first premolar root concavity on clinical indices of chronic periodontal disease and alveolar bone defects.

METHODS

Three-dimensional reconstruction by cone beam computed tomography was used to observe root surface anatomy and the type of alveolar bone defect seen in the mesial and distal sites of 272 first premolars from 99 patients who had presented with chronic periodontitis. Periodontal clinical indicators at each site were measured using a Florida Probe Corporation (Gainesville, FL, USA).

RESULTS

The incidence of mesial and distal root concavities of the maxillary first premolars was 100% and 39.3% respectively, and in the mandibular, the incidence was 42.5% and 31.3% respectively. The distributions of the different types of concavities in terms of both age and gender of the patients were not statistically significant. The mean probing depth and clinical attachment loss of the first premolars with root concavities were significantly higher than those without concavity (p < 0.05). Plaque accumulation was significantly different in the premolars with/without root concavities (p < 0.001). The type of alveolar bone defects with concavities was significantly different from those without concavities (p < 0.05). Ramp shape bone defects were dominant for teeth without concavities, while crater shape was seen for teeth with concavities.

CONCLUSION

Root concavities of the first premolars were associated with periodontal disease, and the type of interproximal alveolar bone defect. Root concavities may be important in contributing to local periodontal disease of the first premolars.

Morphometric study of length and grooves of maxillary lateral incisor roots

OBJECTIVE

Root grooves are considered a risk factor for periodontal disease. The purpose of this study was to measure the length of the root of maxillary lateral incisors (MLI), as well as the width and depth of the concavities of their proximal surfaces, and also to determine the prevalence of palato-gingival grooves.

METHODS

the width and depth of root concavities, as well as root length were evaluated in 73 MLI. All teeth were measured using a digital contour measuring instrument for the root grooves and a caliper for evaluating root length.

RESULTS

After statistical analysis (p<0.05) it was possible to confirm: the mean root length on its mesial surface was (15.47+/-1.72 mm), on its distal surface (14.99+/-1.70 mm), on its buccal surface (13.10+/-1.69 mm) and on its lingual surface (12.71+/-1.53 mm); concavities were present in 100% of the samples; concavities were found 2mm, coronally from the CEJ, at the CEJ, and apically up to 8mm; the concavities were wider than deeper; on the mesial surface, the greatest width was (1.05 mm) and the greatest depth was (0.06 mm) both at the CEJ; 5) on the distal surface the greatest width was (0.73 mm) at 6mm apically from the CEJ and the greatest depth was (0.003 mm); the palato-gingival groove was observed in 9.58% of the samples.

CONCLUSIONS

The mesial surface of the maxillary lateral incisor is the longest. The root concavities on the proximal surfaces are present in 100%. One must get acquainted to the morphological variations of roots to enhance diagnosis and treatment.

Periodontal disease and tooth loss

Numerous epidemiological studies have shown that caries is the main reason for tooth loss. More recent epidemiological data seem to show an increasing trend of tooth loss due to periodontal reasons rather than caries. In considering the issue of periodontal disease and tooth loss the following observations were made. The presence of initial attachment loss, bone height and the habit of smoking significantly increase the risk of tooth mortality. There is a strong correlation between smoking, the severity of periodontal disease and tooth mortality. Cross-sectional population surveys of tooth loss reported lower anterior teeth to be the most frequently extracted due to periodontal reasons, followed by upper anteriors and upper second molars. However, in long term maintenance studies, molars were lost most frequently. Periodontal reasons for tooth loss were mainly mobility followed by furcation involvement. Periodontal surgery did not significantly enhance tooth retention in high risk groups. Ethnic differences observed were not significant and would need further investigations to address variables such as cultural differences, health habits, diet and socio-economic status. In conclusion, periodontal tooth mortality was found to be associated with the loss of periodontal attachment and risk groups with advanced periodontitis contributing to major tooth loss in a minority of the population.