Factors affecting periodontal healing of the adjacent second molar after lower third molar surgery: a systematic review and meta-analysis

Assessment of Changes in the Outcome of Autogenous Tooth Grafts Over Time: A Clinical Study Evaluating Periodontal Healing in Bone Defects After Lower Third Molar Removal

BACKGROUND

The removal of impacted lower third molars (ILTMs) is associated with bone defects in the distal area of second molars. Different methods have been described to minimize these defects.

PURPOSE

The primary objective was to assess changes in probing depth (PD) over time (up to 36 months) between test (grafted) and control (ungrafted) groups; the graft was obtained from the extracted ILTM.

STUDY DESIGN, SETTING, SAMPLE

This split-mouth randomized clinical trial was conducted at the Postgraduate Course in Oral Surgery of the Faculty of Dentistry of the Complutense University of Madrid. Adult patients requiring bilateral ILTM extraction with adjacent second molars were recruited, excluding pregnant/lactating women, patients in treatment with nonsteroidal anti-inflammatory drugs and patients with periodontal diseases.

PREDICTOR/EXPOSURE/INDEPENDENT VARIABLE

The predictor variable was the graft technique. The bone defect after ILTM removal was treated with autogenous tooth graft (ATG) in the test group, leaving the control group ungrafted.

MAIN OUTCOME VARIABLE

PD on the distobuccal, distomedial, and distolingual surfaces was recorded in both groups and averaged at baseline (T0), 3 (T1), 6 (T2), and 36 months (T3) postoperatively.

COVARIATES

Sex, age, surgical time, ILTM situation and position between groups were assessed.

ANALYSES

ANOVA repeated measures for comparisons between groups and the Friedman test for comparisons within the groups over time were applied. Statistical significance was established with a confidence interval of 95% (P < .05).

RESULTS

The sample comprised 22 patients (6 males, 16 females) with a mean age of 21.68 ± 2.19 years; 44 ILTM extractions were performed. Statistically significant differences in PD average were found between groups (P < .001, 95% confidence interval) at 3 (1.63 ± 0.29), 6 (1.76 ± 0.3), and 36 months (1.74 ± 0.36). Reductions from T0 to T3 of 2.74 ± 0.28 (P < .001) and 0.54 ± 0.3 (P = .43) were observed in test and control groups, respectively.

CONCLUSION AND RELEVANCE

ATG placed on the distal surface of lower second molars and almost completely filling the extraction socket improved PD 3, 6 and 36 months after ILTM. Furthermore, no significant changes in PD were observed over time; no major complications occurred. ATG appears to be a viable alternative graft material for this procedure.

Relationship between the Status of Third Molars and the Occurrence of Dental and Periodontal Lesions in Adjacent Second Molars in the Polish Population: A Radiological Retrospective Observational Study

The aim of this study was to evaluate the effect of third molars on caries, external root resorption, and alveolar bone loss on the distal surface of adjacent second molars. A total of 2488 panoramic radiographs of adult Poles were evaluated. Third molars were classified, according to eruption status, into non-impacted, partially, or completely impacted, and according to angulation into horizontal, mesioangular, vertical, and distoangular. Completely impacted third molars were assigned as reference group. The odds ratios (ORs) and 95% confidence intervals for the occurrence of the above-mentioned pathologies were 1.39 (1.09-2.21), 6.51 (3.72-10.11), and 2.42 (1.22-4.09), respectively, for second molars with adjacent erupted third molars and 1.54 (1.11-2.82), 10.65 (7.81-20.19), and 5.21 (3.38-10.81), respectively, when partially impacted third molars were next to second molars. The ORs of lesions were significantly higher for horizontally and mesioangularly impacted third molars. Within the limitation of a radiological study, it might be concluded that the presence of erupted third molars is a risk factor for caries, while the presence of impacted third molars increases the risk of root resorption and bone loss on the distal surface of second molars.

Six-Month Soft Tissues Healing after Lower Third Molar Extraction: Comparison of Two Different Access Flaps

BACKGROUND

As specific flap designs performed for lower third molar extractions usually influence periodontal healing of the adjacent first and second molars, this study aimed to evaluate the periodontal conditions of these sites after 6 months post-surgery.

METHODS

Forty patients, aged 14-30 years, were included. Surgical extraction of the lower third molar was performed through a flap with papilla detachment (a modified envelope technique with detachment of gingival papilla between the first and second molars) or a trapezoidal flap (characterized by mesial- and distal-releasing incisions). Periodontal parameters at the first and second molar sites were assessed for visible plaque index, bleeding on probing, recession, probing pocket depth, and clinical attachment loss before surgery (T0), one month (T1), and six months after extraction (T2).

RESULTS

No statistical differences were found for the plaque and bleeding indexes between the two flaps at each observation time and considering both time intervals. For recession, no statistical differences were found between the two flaps considering the final time interval. For probing pocket depth at the second molar site, both techniques registered a significant increase between T0 and T1, followed by a decrease up to T2. For clinical attachment loss, mean values assessed for the first and second molar sites demonstrated evidently increased values between T0 and T1, followed by moderate decreases up to T2.

CONCLUSIONS

Considering short (T1) and mid-term (T2) follow-ups, a specific flap design does not seem to particularly influence periodontal healing six months after surgery.

Effect modifiers influencing the periodontal healing of the adjacent second molar following mandibular third molar removal

DATA SOURCES

Studies were selected, using appropriate key words, from the following databases: Cochrane Central Register of Controlled Trials; Medline (via Pubmed); Scopus/Elsevier; and Embase. A manual search was also conducted of five periodontology and oral and maxillofacial surgery journals. It was not clarified what proportion of studies included were derived from which source.

STUDY SELECTION

Inclusion criteria included prospective studies and randomised controlled trials published in English, with a minimum 6-month follow-up reporting on parameters of periodontal healing distal to the mandibular second molar following removal of M3M in human subjects. These parameters included pocket probing depth (PPD) reduction and final depth (FD), clinical attachment loss (CAL) reduction and FD, alveolar bone defect (ABD) change and FD. Given prognostic indictors and interventions were investigated, the studies were screened using PICO and PECO (Population, Intervention, Exposure, Comparison, Outcome). Cohen's kappa statistic measured the level of agreement between 2 selecting authors (0.96 stage 1 screening, 1.00 stage 2 screening). Disagreements were resolved with a tie-breaker 3rd author. Ultimately, from 918 studies, 17 met the inclusion criteria and 14 were included in the meta-analysis. Studies were excluded on the basis of same patient pools, non-representative outcomes of interest, insufficient follow-up period, and unclear results.

DATA EXTRACTION AND SYNTHESIS

The 17 studies meeting the inclusion criteria underwent validity assessment and data extraction, including risk of bias analysis. Meta-analysis was performed to calculate mean difference and standard error for each outcome measure. If these were unavailable, a correlation coefficient was calculated. Meta-regression was used on different subgroups to determine factors affecting periodontal healing. For all analyses, statistical significance was determined as p < 0.05. Statistical variability in outcomes beyond the expected was estimated using I² analyses, with a value >50% indicating significant heterogeneity.

RESULTS

The periodontal parameters investigated yielded the following results after meta-analysis: overall PPD reduction of 1.06 mm at 6 months and 1.67 mm at 12 months; final PPD of 3.81 mm at 6 months; CAL change of 0.69 mm at 6 months; final CAL of 4.28 mm at 6 months and 4.37 mm at 12 months; ABD reduction of 2.62 mm at 6 months; ABD of 3.2 mm at 6 months. The authors found no statistically significant effect on periodontal healing from the following confounding factors: age; M3M angulation (specifically, mesioangular impaction); optimisation of periodontal health prior to surgery; scaling and root planing of the distal second molar at the time of surgery; post-operative antibiotics or chlorhexidine prophylaxis. There were statistically significant correlations between baseline PPD and final PPD. There was improved PPD reduction at 6 months with a three-sided flap compared to others, and regenerative materials and bone grafts improved all periodontal parameters.

CONCLUSIONS

Although M3M removal results in modest improvement in periodontal health distally of the second mandibular molar, periodontal defects remain onwards of 6 months. There is limited evidence suggesting a three-sided flap is more beneficial than an envelope flap in PPD reduction at 6 months. Regenerative materials and bone grafts result in significant improvements across all periodontal health parameters. The most important predictive factor in final PPD of the distal second mandibular molar is baseline PPD.

Application of Cone Beam Computed Tomography in Risk Assessment of Lower Third Molar Surgery

Risks of lower third molar surgery like the inferior alveolar nerve injury may result in permanent consequences. Risk assessment is important prior to the surgery and forms part of the informed consent process. Traditionally, plain radiographs like orthopantomogram have been used routinely for this purpose. Cone beam computed tomography (CBCT) has offered more information from the 3D images in the lower third molar surgery assessment. The proximity of the tooth root to the inferior alveolar canal, which harbours the inferior alveolar nerve, can be clearly identified on CBCT. It also allows the assessment of potential root resorption of the adjacent second molar as well as the bone loss at its distal aspect as a consequence of the third molar. This review summarized the application of CBCT in the risk assessment of lower third molar surgery and discussed how it could aid in the decision-making of high-risk cases to improve safety and treatment outcomes.