06 March 2019

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Can the distal space on the second molar, after the germectomy of the lower third molar, cause the onset of delayed infections?

Co-authors: G. Monaco, S. Cecchini, G.A. Pelliccioni.

Maria Gatto

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Late infections resulting from the surgical removal of third molars, despite having a relatively low incidence (from 0.5% to 1.8%), represent a significant problem for the surgeon; in fact the late onset (between two and 8 weeks after surgery) of pain and swelling as well as the need to undergo antibiotic therapy induce the patient to consider him responsible or of little information or to have minimized the possibility of appearance of alveolitis.
The aim of this retrospective study is to highlight the existence of an association between the lack of distal space (IIC or IIIC class of Pell and Gregory) and the onset of alveolitis after the extraction of third mandibular molars included.  

MATERIALS AND METHODS
134 patients (68 males and 66 females) who had one or two mandibular third molar germs extracted at least six months before the start of the study. 218 germectomies performed between 2010 and 2013 were evaluated. For each tooth the numerical value of the space / amplitude ratio was calculated based on the Ganns protocol, analyzing on OPT the relationship between the available space in the retromolar region and the mesiodistal amplitude of the crown of the third molar. A single operator, different from the oral surgeon, calculated the Ganss ratio and recorded the cases of alveolitis. 
Statistical analysis
The discriminant analysis, stepwise modality, was used to identify the best combination of clinical predictors of alveolitis appearance. A set of 62 germectomies, different from those on which the discriminant analysis was performed, was used to validate the results obtained.  

RESULTS
18 patients presented with alveolitis (13.4%), without significant differences in age and gender; however, the male / female ratio was a significant predictor of late infection being 0.64 in patients with alveolitis and 1.11 in patients without alveolitis (p = 0.0001). Demographic parameters (age) and clinical parameters (duration of surgery, Ganss ratio) analyzed only the Ganss ratio proved to be a significant predictor of the appearance of late infection (p = 0.007). The Ganss ratio was 0.40 ± 0.20 in patients with alveolitis and 0.53 ± 0.21 in patients without alveolitis (p = 0.004). The efficacy of the Ganss ratio in the classification of cases of late infection evaluated with the ROC curve yielded at a cut-off of 0.5 an estimated sensitivity of 75% (95% confidence interval: 68% -82%) and a specificity of 62% (95% confidence interval: 54% -70%). The validation of the results on the sample of 62 germectomies confirmed the importance of the ratio of Ganss higher than 0.5 in the prediction of the absence of alveolitis (specificity of 50%), but showed a sensitivity lower than that denoted by the ROC curve, probably at due to the reduced sample size.

DISCUSSION
The hypothesis that when the distal space at the second molar is extremely reduced (ratio of Ganss <0.5) is more likely to develop a late infection due to the presence of food is confirmed. In fact, in 16 of the 20 cases of alveolitis (one patient had infection in bilateral surgical sites) the ratio of Ganss was less than 0.5, the incidence of late infections detected in this retrospective study is higher than that reported in the literature; according to the incidence thresholds proposed in the guidelines of the US National Institute of Health (5%) and those of the United Kingdom's Right Honorable Justice Lawton (probability of infection greater than 1 in 100), all patients should be informed of the possibility of the appearance of these late post-operative complications.

CONCLUSIONS 
The limited sample size of this study suggests that further studies on larger populations are performed. However, the surgical protocol adopted can be standardized so that the only anatomical variable is the presence of a reduced distal space at the second molar and the total inclusion.  

For additional informations:
Delayed onset infections after lower third molar germectomy could be related to the space distal to the second molar