A radiographic analysis of short-term outcomes of second molars in proximity to wisdom teeth in periodontal patients (A retrospective radiographic study)

Abstract

Objective: To evaluate radiographic changes in the alveolar bone on the distal surface of the second molars (2Ms) in the continued presence of impacted or semi-impacted third molars (ITMs) and following short term period with or without intervention.

Materials and Methods: This was an observational study to assess the radiographic changes in the alveolar bone between two time points (T0) and (T1). Available x-rays were used and three measurements were taken on the distal surface of the 2Ms: (i) a vertical distance from the cementoenamel junction (CEJ) to the deepest apical bone extension of the intra-bony defect (BD); (ii) an oblique straight distance from BD to the most coronal position of the alveolar bone crest of the intra-bony defect (CB); and (iii) the angle formed from the vertical line from the identified CEJ to BD with an oblique line from BD to CB. The EMAGO 6.1 software was used to analyse the x-rays. The data was transferred to SPSS version 29.0, operating on the Mac OS platform. The database was secured upon completion. Descriptive statistics were then computed to provide an initial overview of the data. Statistical significance in the analysis was established with a threshold of p-value < 0.05 to ascertain significant differences between measurements obtained at different time points.

Results: The retrospective analysis identified a total of 125 patients (9.6%) suitable for analysis out of 1302 patients (100%) through patient records as having either impacted or semi-impacted 3Ms. The mean age was 45 years with a standard deviation (SD) of 13 years. Out of the 125 patients, 218-second molars were analysed at T0 and only 68-second molars at T1 with a time interval of approximately 20 months, with a std. error of mean (SEM) estimated to be 62 days. In the initial findings, it was observed that ITMs in the mandible were higher compared to their upper counterparts, accounting for 73.7% of the cases at T0 and 81% at T1. Maxillary impaction was observed in only 26.7% of cases at T0 and 19% at T1. The most frequent angle of impaction was mesioangular, followed by vertical, distoangular, horizontal, and inverted impactions. Regarding the main results, no significant differences were found in vertical and oblique bone changes or angular bone changes between certain landmarks between T0 and T1. Gender significantly influenced the distribution of the linear measurement CEJ to BD (p= 0.022) not however, of the measurement between the BD and CB. The distribution of intrabony defect angle according to gender was statistically significant at T0 but not at adjusted T1, with p-values of 0.048 and 0.292, respectively. Analysing according to medical history, medication, ethnicity, smoking status, and ITM angulation did not show significant effects on any radiographic measurements or time points. However, patient age did seem to correlate with intrabony defect angles that almost reached significance with a p-value of 0.047.

Conclusion: This specific analysis with the limitations presented did not seem to indicate that universal prophylactic ITM extraction would offer significant bone sparing benefit, nor does it show that prolonged ITMs presence will always have a continuous bone damaging effect on nearby 2Ms in the short-term. It suggests further research is needed to quantify the medium to long term risk and confirm or reject the hypothesis whether extraction of ITM can truly improve bone levels at 2Ms.