Faculdade de Medicina Dentária, Universidade de Lisboa, Lisboa.
Instituto de Implantologia, Lisboa, Portugal.
Int Endod J. 2019 Nov;52(11):1556-1572. doi: 10.1111/iej.13169. Epub 2019 Jul 11.
To perform a systematic review of anatomical studies using cone beam computed tomography (CBCT) to assess the influence of demographic factors (age, gender and geographic region) on the prevalence of C-shaped canal anatomy in maxillary molars, mandibular premolars and molars.
A search was conducted between May and August 2018 in four electronic databases and five peer-reviewed journals. The authors of included articles were also contacted for additional studies and the bibliographic references hand-searched.
STUDY ELIGIBILITY CRITERIA, PARTICIPANTS AND INTERVENTIONS: The research protocol was previously registered in the International Prospective Register of Ongoing Systematic Reviews (CRD42018095201) and included defined inclusion/exclusion criteria. Prevalence studies on C-shaped canal anatomy in maxillary molars, mandibular premolars and molars were searched.
The selected studies were submitted to full-text analysis and critical appraisal by two evaluators using the Joanna Briggs Institute Critical Appraisal tool. The final group of papers (n = 25) were pooled and forest plots with proportions and odds ratio with a 95% confidence interval performed. Meta-regression was undertaken to evaluate possible sources of heterogeneity and funnel plot visual analysis to assess publication bias.
The included studies reported data on 25 445 teeth of 13 142 patients. A significant difference in the average prevalence proportion of C-shaped configuration was observed between mandibular first (0.3%; 0.1-0.6%) and second (12%; 10.3-13.7%) molars (P < 0.05). No significant difference in the prevalence of C-shaped configurations was observed comparing males (13.5%; 8.8-18.3%) and females (20.5%; 13.7-27.4%) in mandibular second molars (P > 0.05), although males were associated with significantly lower odds (0.573; 0.511-0.641) (P < 0.05). The pooled proportion of C-shaped anatomy in mandibular second molars in East Asian countries (39.6%; 36.0-43.1%) was significantly higher compared with other regions.
Because of the limited number of studies, no statistical analysis was performed for maxillary molars and mandibular premolars.
Meta-analysis revealed that gender and geographic region may act as a confounding factor for the prevalence of C-shaped anatomy in mandibular second molars, whilst age did not influence the prevalence of C-shaped configurations in this tooth group. Knowing these preoperative factors would help to anticipate complex morphologies in clinics.
采用锥形束 CT（CBCT）进行系统评价，评估年龄、性别和地理位置等人口统计学因素对上颌磨牙、下颌前磨牙和磨牙 C 形根管解剖结构的发生率的影响。
2018 年 5 月至 8 月在四个电子数据库和五份同行评审期刊中进行了检索。还联系了纳入研究的作者以获取其他研究，并对参考文献进行了手工检索。
研究入选标准、参与者和干预措施：该研究方案之前已在国际前瞻性注册持续系统评价（CRD42018095201）中进行了注册，并规定了明确的纳入/排除标准。检索了上颌磨牙、下颌前磨牙和磨牙 C 形根管解剖结构的发生率研究。
两名评估人员对选定的研究进行了全文分析和批判性评估，使用 Joanna Briggs 研究所的批判性评估工具。最终纳入的论文（n=25）被汇总，绘制了带有 95%置信区间的比例和比值比的森林图。进行了元回归以评估可能的异质性来源，并进行漏斗图视觉分析以评估发表偏倚。
纳入的研究报告了 13142 名患者的 25445 颗牙齿的数据。下颌第一磨牙（0.3%；0.1-0.6%）和第二磨牙（12%；10.3-13.7%）之间的 C 形结构平均发生率存在显著差异（P<0.05）。下颌第二磨牙中男性（13.5%；8.8-18.3%）和女性（20.5%；13.7-27.4%）的 C 形结构发生率无显著差异（P>0.05），尽管男性的比值明显较低（0.573；0.511-0.641）（P<0.05）。东亚国家下颌第二磨牙 C 形解剖结构的总发生率（39.6%；36.0-43.1%）明显高于其他地区。
由于研究数量有限，对上颌磨牙和下颌前磨牙未进行统计学分析。
荟萃分析表明，性别和地理位置可能是下颌第二磨牙 C 形解剖结构发生率的混杂因素，而年龄并不影响该牙组 C 形结构的发生率。了解这些术前因素将有助于在临床中预测复杂的形态。
