Reference | Study type | Population | Intervention / Exposure and comparison | Outcomes | Risk of bias «Additional comments for included studies»1 |
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N-M3 = non-impacted third molar
V-M3 = visible third molar I-M3 = impacted third molar * = impaction status (soft tissue/bony) was not analyzed A-M2= adjacent second molar |
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«Chou YH, Ho PS, Ho KY ym. Association between the ...»1 Chou 2017 | Cross sectional | Patients (> 25-years of age, mean age 45 y) with unilateral maxillary or mandibular
fully erupted M3s in Periodontal and Dental departments of two hospitals of Kaohsiung
city, Taiwan.
Excluded if: pregnant, symptomatic M3s, active periodontal treatment, history of smoking, and a systemic condition (uncontrolled diabetes mellitus, using Ca2þ channel blockers, immunosuppressive medication). |
Periodontal disease and caries on second molar (clinical and radiological examination). Comparison between the retained wisdom tooth site and the site with previously extracted wisdom tooth | Plaque index
Bleeding on probing
Periodontal pocket depth (PD)
Caries M3 position |
Control of confounding factors Outcome measurement |
«Li ZB, Qu HL, Zhou LN ym. Nonimpacted Third Molars...»2 Li 2017 | Cross sectional | Patients (> 18 y, mean age 41) with at least 1 quadrant with 3 intact molars and a N-M3 and those with at least 1 quadrant with intact first and second molars without a M3 in the Department of Periodontology at the Stomatological Hospital, Fourth Military Medical University (Xi’an, China). Excluded if systemic disease, antibiotic treatment, pregnant, oral tumors, using interdental cleaning devices, periodontal surgery | Periodontal parameters on M2 Comparison between sites with N-M3 and sites without M3 | Periodontal measurementsof M2: plaque index (PLI), gingival index (GI),PPD, CAL, bleeding on probing (BOP), and gingival recession (GR). The presence of at least 1 PPD5+ | Control of confounding factors Outcome measurement |
«Li ZB, Qu HL, Zhou LN ym. Influence of Non-Impacte...»3 Li 2017 | Cross sectional, retrospective | Radiographic survey | The influence of asymptomatic N-M3s or I-M3* compared to sites without M3 (adjusted for age and sex) | Presence of distal caries, external root resorption (ERR), and alveolar bone loss (ABL) on A-M2s was assessed by orthopantomograms (OPGs) | Control of confounding factors Outcome measurement |
«Qu HL, Tian BM, Li K ym. Effect of Asymptomatic Vi...»4 Qu 2017 | Cross sectional | Subjects with at least 1 quadrant having intact first and second molars, either with asymptomatic V-M3s or without adjacent V-M3s in the Department of Periodontology, Stomatological Hospital, Fourth Military Medical University (FMMU), China. Excluded if systemic disease, pregnancy or menstruation, antibiotic treatment, periodontal surgery, M3 extraction within 6 months | Periodontal parameters on M2 Comparison between sites with V-M3 and sites without M3 | Plaque index (PLI), bleeding on probing (BOP), probing pocket depth (PPD), and at least 1 site with a PPD of 5 mm or more (PPD5+), obtained from M2s | Outcome measurement |
«Ghaeminia H, Perry J, Nienhuijs ME ym. Surgical re...»5 Ghaeminia 2016 | Cochrane systematic review | One study «Ghaeminia H, Perry J, Nienhuijs ME ym. Surgical re...»5 included | Extraction (absence) compared with retention (presence) for managing asymptomatic disease- free impacted wisdom teeth | Periodontal pathology as outcome | Eligibility criteria |
«Nunn ME, Fish MD, Garcia RI ym. Retained asymptoma...»6 Nunn 2013 | Cohort, longitudinal | Subjects with both first and second molars present in at least 1 quadrant at baseline and had at least 1 follow-up examination in U.S. Department of Veterans Affairs Dental | Third molars were categorized for analyses as absent, erupted, or unerupted, with the last subcategorized as either “soft tissue” or “bony” impacted | M2 distal caries experience (either primary or secondary caries), distal alveolar bone loss ≥ 20 %, and distal probing depth > 4 mm. | Control of confounding factors Selection of participants Missing data Outcome measurement |
Results
Reference | Number of studies and number of patients (I/C) | Follow-up time | Absolute number of events (%) I | Absolute number of events (%) C | Relative effect (95 % CI) |
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Level of evidence: high
Most evidence comes from cross-sectional studies however, the magnitude of effect is large especially for soft tissue impacted mandibular wisdom teeth. I = intervention C = comparison CI = confidence interval |
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«Chou YH, Ho PS, Ho KY ym. Association between the ...»1 Chou 2017 | 81/81 wisdom tooth pairs | - | - | - | Higher PD on M2 on the nonextraction side than the extraction side, p = 0,006 |
«Li ZB, Qu HL, Zhou LN ym. Nonimpacted Third Molars...»2 Li 2017 | 135 patients | - | - | - | OR of having at least 1 PPD5+ in the A-M2s if N-M3 was present 6,79 (1,1–40,2) in mandibular arch 3,33 (1,68–6,59) if patient > 35 y 5,77 (1,27–25,89) male 1,4 (1,1–1,5) smoker 1,7 (1,2–1,9) |
«Li ZB, Qu HL, Zhou LN ym. Influence of Non-Impacte...»3 Li 2017 | 1958 OPGs | - | - | - | Both N-M3 and I-M3 increased the risk for alveolar bone loss in M2 (OR respectively 1,77 (1,51 to 2,08) < 0,001 3,84 (3,28 to 4,50) < 0,001) |
«Qu HL, Tian BM, Li K ym. Effect of Asymptomatic Vi...»4 Qu 2017 | 572 subjects (of which 423 had at least one V-M3) | - | - | - | Impacted M3s and normally erupted M3s significantly elevated the risk of PPD5+ on their A-M2s (odds ratio 3.20 and 1,67, respectively) |
«Ghaeminia H, Perry J, Nienhuijs ME ym. Surgical re...»5 Ghaeminia 2016 | 416 subjects | 3–25 years | - | - | Absence of M3 shows RR of 0,11 (95 % CI 0,06 to 0,22) for periodontal pathology compared to soft tissue impacted M3 |
«Nunn ME, Fish MD, Garcia RI ym. Retained asymptoma...»6 Nunn 2013 | 416 subjects | 3–25 years | - | - | Second molars adjacent to soft tissue impacted third molars were more likely to have distal bone loss ≥ 20 % (OR = 4,93) and distal probing depth > 4 mm (OR = 3,98). Second molars adjacent to bony impacted third molars were more likely to have distal bone loss ≥ 20 % (OR = 2,64). |