Short (≤6 mm) compared with ≥10-mm dental implants in different clinical scenarios: A systematic review of randomized clinical trials with meta-analysis, trial sequential analysis and quality of evidence grading.

AIM: To systematically identify, synthesize and critically summarize the available scientific evidence from randomized controlled trials (RCTs) regarding whether short (≤6 mm) perform as well as long (≥10 mm) implants regarding implant survival, marginal bone loss, and biologic and prosthetic complications in different clinical scenarios. MATERIALS AND METHODS: Cochrane Collaboration's risk of bias tool and the GRADE approach were applied. Results were synthesized using random-effects meta-analyses assessed by trial sequential analyses. RESULTS: Forty reports on 19 RCTs comprising 2214 (1097 short; 1117 long) implants were included. Moderate/high certainty/quality evidence demonstrated similar 5-year survival rates for ≤6-mm and ≥10-mm implants in non-augmented bone and full-mouth rehabilitation in either jaw, and for 6-mm implants in the maxilla instead of sinus lift. Nevertheless, the evidence for 5-year survival rates remains inconclusive or insufficient for the remaining combinations of implant lengths and clinical scenarios. They include 4-mm and 5-mm implants as alternatives to sinus lift as well as placing all implant lengths ≤6 mm instead of vertical ridge augmentation with long implants. Marginal bone level and short- and long-term biologic or prosthetic complications were similar. CONCLUSIONS: Based on moderate/high certainty/quality evidence from 5-year RCTs, implants ≤6 mm may be viable alternatives to ≥10-mm implants in either jaw in native bone and full-arch rehabilitation, and 6-mm implants may be used as an alternative to sinus lift. TRIAL REGISTRATION: PROSPERO ID: CRD42021254365.

Adjunctive use of locally delivered host-modulators in intra-bony defects as part of step 2 periodontal therapy: systematic review, meta-analysis and trial sequential analysis.

BACKGROUND: This systematic review and meta-analysis aimed at investigate the role of locally delivered host-modulators in combination with step 2 of periodontal therapy in reducing probing pocket depth, improving clinical attachment level and reducing bone defect depth in intra-bony defects. HIGHLIGHT: RCT with at least 6 months follow-up were included in this study. Risk of bias assessment was performed with Cochrane collaboration tool and Grade GRADEpro. In addition, meta-analysis and trial sequential analysis were used to aggregate the available evidence. 22 studies met the inclusion criteria and were included in this systematic review. At 6 months locally delivered host-modulators significantly improved PD and CAL and bone defect depth. CONCLUSION: Considering the emerging role of host-inflammatory response in the treatment of periodontitis, several studies are exploring the role of locally delivered host modulators as an adjunct to step 2 of periodontal therapy.

Antibiotic prophylaxis at the time of dental implant placement: a cost-effectiveness analysis.

BACKGROUND: Antibiotic prophylaxis during implant placement may improve implant short term survival. Nevertheless, use of antibiotics carries risks of adverse effects and antibiotic resistance. The aim of the present study is to compare the use of antibiotics in dental implant procedures in terms of costs and effectiveness. METHODS: A decision-tree model was developed using TreeAge Pro Healthcare software. Two strategies were compared: Antibiotics and No antibiotics in implant placement procedures. The costs were calculated considering direct costs for implant placement, antibiotic costs, and costs for implant replacement in case of failure. Effectiveness was defined in terms of General Oral Health Assessment Index. Outcomes were evaluated as Incremental Cost Effectiveness Ratio (ICER). One-way sensitivity analysis and Probabilistic Sensitivity Analysis were performed for the most influential variables to test parameter uncertainty. Patient and healthcare perspectives were considered. RESULTS: Antibiotic prophylaxis resulted to be cost-effective compared to no use of antibiotics (ICER = 14,692,64 and ICER = 3841,18, respectively for patient's and healthcare perspective). The cost of antibiotics, cost of implant replacement in case of failure and probability of adverse effects significantly influenced the results. CONCLUSIONS: From an individual patient perspective, antibiotic strategy can be considered cost-effective, even when the cost of antibiotic therapy increases. We can conclude that the administration of antibiotics in association with implant placement is recommended in clinical practice, as it increases the success rate and makes the treatment more effective. However, attention should be placed when healthcare perspective is considered, particularly in terms of antibiotic resistance that may impact public health and associated costs.

Root Membrane Replantation as an Alternative Technique for the Socket Preservation.

Background and Overview. Socket shield is a technique that allows the maintenance of tissue volumes. In the reported clinical case, the replantation of the buccal root fragment mistakenly extracted during a socket shield surgery is performed. We present a follow-up to 5 years with an unexpected healing.Case Description. An 88-year-old patient underwent an immediate loading implant placement associated with the replantation of the mistakenly extracted root fragment. The shaping of the fragment was performed extraorally, and the replantation was done so that the fragment protruded above the crest margin.Conclusions and Practical Implications. The 5-year follow-up shows an uneventful healing of the implant. At 48 months, postoperative CBCT exam reports images compatible with the regeneration of the bone over the portion of root that protruded over the margin. The outcome suggests clinical implications, as the opportunity to easily shape the fragment extraorally and replant sound portion of the root (not necessary the buccal) in buccal socket with bone defect.

The role of keratinized mucosa width as a risk factor for peri-implant disease: A systematic review, meta-analysis, and trial sequential analysis.

BACKGROUND: Studies have examined the benefit of having keratinized peri-implant mucosa width with mixed results. PURPOSE: This study examines whether the lack of a prespecified (2 mm) amount of keratinized mucosa width (KMW) is a risk factor for peri-implant diseases. METHODS: A systematic electronic and manual search of randomized or nonrandomized controlled or noncontrolled clinical trials was conducted. Qualitative review, quantitative meta-analysis, and trial sequence analysis (TSA) of implants inserted at sites with <2 mm or ≥2 mm of KMW were analyzed to compare all the predetermined outcome variables. The level of evidence concerning the role of KMW in peri-implant health was evaluated via the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) system guide. RESULTS: Nine studies were included in the qualitative analysis and four in the meta-analysis and TSA. No significant inter-group difference (p > 0.05) and a low power of evidence were found for probing depth, soft-tissue recession, and marginal bone loss. A significant difference favoring ≥2 mm KMW had a lower mean plaque index (MD = 0.37, 95% CI: [0.16, 0.58], p = 0.002) (3 studies, 430 implants, low-quality evidence). GRADE system showed very low and low quality of evidence for all other outcome measures. CONCLUSION: Based on the available studies, the impact of amount of KMW (either <2 mm or ≥ 2 mm) as a risk factor for developing peri-implant disease remains low. Future control studies with proper sample size and longer follow-up are needed to further validate current findings.

Added effect of 1% topical alendronate in intra-bony and inter-radicular defects as part of step II periodontal therapy: a systematic review with meta-analysis and trial sequential analysis.

BACKGROUND: This systematic review and meta-analysis aimed to investigate the role of alendronate combined with step 2 of periodontal therapy in reducing probing pocket depth, improving clinical attachment level, and reducing bone defect depth in intra-bony and inter-radicular defects. METHODS: RCTs with more than 6 months follow-up were included in this study. Risk of bias assessment was performed using the Cochrane collaboration tool. In addition, meta-analysis and trial sequential analysis were used to aggregate the available evidence. RESULTS: Seven studies met the inclusion criteria and were included in the systematic review. Topical application of alendronate during second step of periodontal therapy significantly improved PD and CAL. CONCLUSION: Local application of alendronate may confer a beneficial effect when applied during step II of periodontal therapy even if long term studies are needed to confirm these results. CLINICAL RELEVANCE: Considering the emerging role of host-inflammatory response in treatment of periodontitis and the antiresorptive and osteostimulative properties of bisphosphonates, several studies are focusing on the role of alendronate as an addition to non-surgical periodontal therapy.

Prognostic assessment of different methods for eosinophils detection in oral tongue cancer.

BACKGROUND: TATE has been proposed as a prognostic factor in oral cancer staging; however, the controversial literature data limit its application in the routine diagnosis. The aim of this study was to evaluate the prognostic value of TATE in patients with oral tongue cancer. The second aim was to identify any difference in the methods of eosinophil quantification or in the cutoff values reported in literature. METHODS: Clinic-pathological data of 204 patients treated at "Ospedali Riuniti" Hospital, Ancona, Italy, were collected. Evaluation of TATE was performed on hematoxylin-and-eosin-stained slides and correlation with survival outcomes was evaluated. The number of eosinophils per square millimeter was evaluated by using two methods, namely density (TATE-1) and classical (TATE-2) methods. For each of the 2 methods tested, patients were stratified into two or three groups, according to the most used cutoff values reported in literature. RESULTS: Regardless of the method of eosinophil quantification or the cutoff values used, patients with high TATE had a significantly better disease-specific survival. The density method (TATE-1) showed a better predictive performance, in particular when applying a single cutoff of 67 eosinophils/mm2 , two cutoffs of 10 and 100 eosinophils/mm2 , or two cutoffs of 50 and 120 eosinophils/mm2 . CONCLUSION: The evaluation of TATE is simple, cost-effective, and easy to implement in daily practice with the aim of improving risk stratification of patients affected by oral tongue cancer. Results of prognostic performance analysis suggest using density (TATE-1) method as the standard approach to evaluate TATE in future studies, enhancing replicability.

Innate Immunity in Children and the Role of ACE2 Expression in SARS-CoV-2 Infection.

COVID-19 (Coronavirus Disease 2019) is an emerging viral disease caused by the coronavirus SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2), which leads to severe respiratory infections in humans. The first reports came in December 2019 from the city of Wuhan in the province of Hubei in China. It was immediately clear that children developed a milder disease than adults. The reasons for the milder course of the disease were attributed to several factors: innate immunity, difference in ACE2 (angiotensin-converting enzyme II) receptor expression, and previous infections with other common coronaviruses (CovH). This literature review aims to summarize aspects of innate immunity by focusing on the role of ACE2 expression and viral infections in children in modulating the antibody response to SARS-CoV-2 infection. This review was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Articles deemed potentially eligible were considered, including those dealing with COVID-19 in children and providing more up-to-date and significant data in terms of epidemiology, prognosis, course, and symptoms, focusing on the etiopathogenesis of SARS-CoV-2 disease in children. The bibliographic search was conducted using the search engines PubMed and Scopus. The following search terms were entered in PubMed and Scopus: COVID-19 AND ACE2 AND Children; COVID-19 AND Immunity innate AND children. The search identified 857 records, and 18 studies were applicable based on inclusion and exclusion criteria that addressed the issues of COVID-19 concerning the role of ACE2 expression in children. The scientific literature agrees that children develop milder COVID-19 disease than adults. Milder symptomatology could be attributed to innate immunity or previous CovH virus infections, while it is not yet fully understood how the differential expression of ACE2 in children could contribute to milder disease.

Everolimus therapy and side­effects: A systematic review and meta­analysis.

Recent studies have focused on identifying novel targeted agents in order to reduce the undesired side­effects of conventional chemotherapeutic agents on normal cells. However, even targeted therapies may exert certain negative effects on healthy tissues. The present systematic review was performed in order to evaluate the type and the incidence of side­effects in patients treated with everolimus. The PubMed and Scopus databases were searched using the following free words and MESH terms: 'everolimus' AND 'side­effects' OR 'toxicities' OR 'adverse events'. A total of 912 potentially relevant studies that were screened based on the title and abstracts were identified. A total of 731 were excluded as they did not fulfil the inclusion criteria. Of the 181 remaining studies included, the adverse events reported were obtained. The primary adverse events reported were stomatitis, leukopenia, anorexia, anaemia and fatigue. The majority of the patients reported adverse events limited to grade 1 or 2. On the whole, the data presented herein confirm the findings of previous studies on the relative safety of everolimus, a targeted therapeutic agent, which differs from that of conventional chemotherapy, and highlight the potential adverse events associated with the therapeutic use of everolimus.

Influence of sterilization procedures on the physical and mechanical properties of rotating endodontic instruments: a systematic review and network meta-analysis.

The fracture of endodontic instruments inside the canal represents a problem that is not always easy to solve. The reutilization of endodontic instruments after sterilization procedures raises the question of how these processes affect their physical and mechanical properties. Alterations can involve the surface of the instruments, as well as their cutting effectiveness, shape and resistance to torsional and cyclic fatigue. The methodology adopted for this systematic review followed the PRISMA guidelines for systematic reviews. The following search terms were used in PubMed and Scopus: "endodontic sterilization", "endodontic autoclave", "cyclic fatigue", "torsional", "cutting efficiency", "sterilization", "surface characteristics" and "corrosion". After the screening phase, the application of exclusion criteria and the removal of duplicates, 51 studies were identified and divided into four outcomes: cyclic fatigue; deformation and torsional fatigue; corrosion or surface alterations; and cutting efficiency. Our study of the scientific literature highlights disagreements between studies on these effects. After autoclaving, instruments exhibit a reduction in the cutting efficiency, but NiTi alloy instruments have an improved resistance to cyclic and torsional fatigue.

Periodontal infrabony defects: Systematic review of healing by defect morphology following regenerative surgery.

BACKGROUND: It is thought that infrabony defect morphology affects the outcome of periodontal regenerative surgery. However, this has not been systematically investigated. AIMS: To investigate how well defect morphology is described in papers reporting regenerative therapy of periodontal infrabony defects and to investigate its effect on clinical and radiographic outcomes. MATERIALS AND METHODS: A search was conducted in 3 electronic databases for publications reporting clinical and radiographic outcomes of periodontal intra-bony defects after regenerative therapy, divided by defect morphology. RESULTS: The initial search resulted in 4487 papers, reduced to 143 after first and second screening. Fifteen of these publications were suitable for a fixed-effects meta-analysis. Initial defect depth was found to influence radiographic bone gain 12 months post-surgery, while narrower angles and increased number of walls influenced both radiographic bone gain and clinical attachment level (CAL) gain at 12 months. These associations seemed to occur irrespective of biomaterials used. Risk of bias ranged from low to high. CONCLUSION: Deeper defects with narrower angles and increased number of walls exhibit improved CAL and radiographic bone gain at 12 months post-regenerative surgery. More data are needed about other aspects of defect morphology such as extension to buccal/lingual surfaces.

Computational analysis of TP53 mutational landscape unveils key prognostic signatures and distinct pathobiological pathways in head and neck squamous cell cancer.

BACKGROUND: Mutations of the tumour-suppressor gene TP53 are the most frequent somatic genomic alterations in head and neck squamous cell carcinoma (HNSCC). However, it is not yet clear whether specific TP53 mutations bear distinct clinical and pathophysiological significance in different HNSCC subgroups. METHODS: A systematic bioinformatics appraisal of TP53 mutations was performed on 415 HNSCC cases available on The Cancer Genome Atlas (TCGA). The following features were analysed and correlated with known clinicopathological variables: mutational profile of TP53, location (within secondary structure and predicted domains of p53 protein) and well-known hotspot mutations. Interactome-genome-transcriptome network analysis highlighted different gene networks. An algorithm was generated to develop a new prognostic classification system based on patients' overall survival. RESULTS: TP53 mutations in HNSCCs exhibited distinct differences in different anatomical sites. The mutational profile of TP53 was an independent prognostic factor in HNSCC. High risk of death mutations, identified by our novel classification algorithm, was an independent prognostic factor in TCGA HNSCC database. Finally, network analysis suggested that distinct p53 molecular pathways exist in a site- and mutation-specific manner. CONCLUSIONS: The mutational profile of TP53 may serve as an independent prognostic factor in HNSCC patients, and is associated with distinctive site-specific biological networks.

Reading-writing disorder in children with idiopathic epilepsy.

Several studies have documented learning disabilities (LDs) in subjects with epilepsy, who have been shown to be at greater risk of mild neuropsychological damage, with the consequent risk of academic failure. This retrospective study aimed to investigate the peculiarities of reading and writing disorders in subjects with idiopathic epilepsy. The reading and writing performance of 35 children affected by reading and writing disorders and idiopathic epilepsy (R/WD + E group) has been compared with the performance of 37 children with only reading and writing disorders (R/WD group). A comparison group of 22 typical developing healthy children (TDC group) was also included in the study. As expected, the TDC group reached better performances in the reading and writing tests administered. Between R/WD + E and R/WD groups, there was a substantial analogy in reading and writing disabilities. The differences between the two clinical groups concern writing ability in sentences dictation and verbal and visuospatial short-term memory in digit span and memory-for-location (MFL) tests.

Management of Instrument Sterilization Workflow in Endodontics: A Systematic Review and Meta-Analysis.

Endodontic treatment consists of different working procedures, such as the isolation of the operating field, pulp chamber access, and cleaning and shaping phases with at last the need of a three-dimensional filling of the canals. Each step requires a series of single-use or sterilizable instruments. We have performed a systematic review of different sterilization and disinfection procedures aiming at drawing up a disinfection and sterilization procedure to be used on endodontic instruments. A search on PubMed and Scopus was carried out using the following keywords: "endodontic sterilization," "endodontic autoclave," "decontamination dental bur," "sterilization dental burs," and "gutta-percha points sterilization." Eligible articles were included in the qualitative and quantitative analysis. Results of the meta-analysis showed that the most effective method in sterilization is autoclaving. The qualitative analysis showed that the use of single-use or first-use instruments requires presterilization or sterilization procedures, and for reusable tools, attention must be paid to the removal of debris deposited on the blades, not easy to remove manually.

Immunohistochemical Analysis Revealed a Correlation between Musashi-2 and Cyclin-D1 Expression in Patients with Oral Squamous Cells Carcinoma.

AIM: Musashi 2 (MSI2), which is an RNA-binding protein, plays a fundamental role in the oncogenesis of several cancers. The aim of this study is to investigate the expression of MSI2 in Oral Squamous Cell Carcinoma (OSCC) and evaluate its correlation to clinic-pathological variables and prognosis. MATERIALS AND METHODS: A bioinformatic analysis was performed on data downloaded from The Cancer Genome Atlas (TCGA) database. The MSI2 expression data were analysed for their correlation with clinic-pathological and prognostic features. In addition, an immmunohistochemical evaluation of MSI2 expression on 108 OSCC samples included in a tissue microarray and 13 healthy mucosae samples was performed. RESULTS: 241 patients' data from TCGA were included in the final analysis. No DNA mutations were detected for the MSI2 gene, but a hyper methylated condition of the gene emerged. MSI2 mRNA expression correlated with Grading (p = 0.009) and overall survival (p = 0.045), but not with disease free survival (p = 0.549). Males presented a higher MSI2 mRNA expression than females. The immunohistochemical evaluation revealed a weak expression of MSI2 in both OSCC samples and in healthy oral mucosae. In addition, MSI2 expression directly correlated with Cyclin-D1 expression (p = 0.022). However, no correlation has been detected with prognostic outcomes (overall and disease free survival). CONCLUSIONS: The role of MSI2 expression in OSCC seems to be not so closely correlated with prognosis, as in other human neoplasms. The correlation with Cyclin-D1 expression suggests an indirect role that MSI2 might have in the proliferation of OSCC cells, but further studies are needed to confirm such results.

Stomatitis And Everolimus: A Review Of Current Literature On 8,201 Patients.

BACKGROUND: Oral toxicities, such as mucositis and stomatitis, are some of the most significant and unavoidable side effects associated with anticancer therapies. In past decades, research has focused on newer targeted agents with the aim of decreasing the rates of side effects on healthy cells. Unfortunately, even targeted anticancer therapies show significant rates of toxicity on healthy tissue. mTOR inhibitors display some adverse events, such as hyperglycemia, hyperlipidemia, hypophosphatemia, hematologic toxicities, and mucocutaneous eruption, but the most important are still stomatitis and skin rash, which are often dose-limiting side effects. AIM: This review was performed to answer the question "What is the incidence of stomatitis in patients treated with everolimus?" METHODS: We conducted a systematic search on the PubMed and Medline online databases using a combination of MESH terms and free text: "everolimus" (MESH) AND "side effects" OR "toxicities" OR "adverse events". Only studies fulfilling the following inclusion criteria were considered eligible for inclusion in this study: performed on human subjects, reporting on the use of everolimus (even if in combination with other drugs or ionizing radiation), written in the English language, and reporting the incidence of side effects. RESULTS: The analysis of literature revealed that the overall incidence of stomatitis after treatment with everolimus was 42.6% (3,493) and that of stomatitis grade G1/2 84.02% (2,935), while G3/4 was 15.97% (558). CONCLUSION: Results of the analysis showed that the incidence of stomatitis of grade 1 or 2 is higher than grade 3 or 4. However, it must be taken into account that it is not possible to say if side effects are entirely due to everolimus therapy or combinations with other drugs.

Possible Uses of Plants of the Genus Asphodelus in Oral Medicine.

Among the many plants used in traditional medicine we have the plants of the genus Asphodelus, which are present in the Mediterranean area in North Africa and South East Asia, and have been used by indigenous peoples until recently for various pathologies, including: Psoriasis, alopecia areata, acne, burns, nephrolithiasis, toothache, and local inflammation. The scientific literature over the last five years has investigated the various effects of the metabolites extracted from plants of the genus Asphodelus, paying attention to the diuretic, antihypertensive, antimicrobial, anti-inflammatory, and antioxidant effects, and it also has begun to investigate the antitumor properties on tumor cell lines. Studies have been identified through bibliographic research on electronic databases. A total of 574 records were identified on the PubMed, Scopus, Web of Science, and EBSCO databases. After having proceeded to the screening of the articles with the application of the eligibility criteria (all the articles pertaining to the issue Asphodelus), we arrived at a number of 163 articles, and then after the elimination of overlaps, to 82 articles. There are 11 articles which investigate the possible uses of plants of the genus Asphodelus in oral medicine. In oral medicine, the possible uses investigated by the scientific literature are for the treatment of neoplastic (melanoma and oral cancer), viral (herpetic viruses), and microbial diseases (candida, bacteriosis, leishmaniasis), and in the affection of the skin.

Inspection of the Microbiota in Endodontic Lesions.

The primary objective of endodontic therapy is to create a biologically acceptable environment within the root canal system that allows for the healing and maintenance of the health of the peri-radicular tissue. Bacteria are one of the main causes of pulp problems, and they have different methods of penetrating and invading the endodontic space such as through carious lesions, traumatic pulp exposures, and fractures. The types of bacteria found range from facultative anaerobes to aerobes, up to the most resistant species able to survive in nutrient-free environments; the bacterial species Enterococcus faecalis belongs to this last group. Enterococcus faecalis is considered one of the main causes of recurring apical periodontal lesions following endodontic treatment, with persistent lesions occurring even after re-treatment. The review presented in this paper was performed in accordance with the PRISMA protocol and covers articles from the related scientific literature that were sourced from PubMed, Scopus, and Google Scholar using the following terms as keywords: "endodontic treatment", "endodontic bacteria", "microbial endodontic", and "endodontic failure". Only the articles considered most relevant for the purposes of this paper were read in full and taken into consideration for the following review. The results show that Enterococcus faecalis, Actinomycetes, and Propionibacterium propionicum are the species most frequently involved in persistent radicular and extra-radicular infections.

Necrotizing sialometaplasia can hide the presence of salivary gland tumors: A case series.

OBJECTIVE: Necrotizing sialometaplasia (NS) is an uncommon benign process which affects minor and, more rarely, major salivary glands. While self-limiting, the condition might be clinically and histologically mistaken for malignancy. Furthermore, NS may accompany neoplasms. The aim of this paper was to report a series of Italian patients affected by NS associated with an unusual high presence of neoplasms of minor and major salivary glands. STUDY DESIGN: Clinical and histological features of twelve patients with NS were retrospectively evaluated. RESULTS: Eight patients presented NS of the minor salivary glands of the palate, and two of them had associated neoplasms (pleomorphic adenoma and adenoid cystic carcinoma) at the same site. Four patients had NS of the parotid gland associated with a history of fine-needle aspiration biopsy performed to diagnose parotid neoplasms. These were epithelial-myoepithelial carcinoma, adenoid cystic carcinoma, Warthin's tumor, and oncocytoma, respectively. CONCLUSION: Tumors of minor and major salivary glands might be associated with NS more frequently than previously reported. While NS of the parotid is generally the result of invasive diagnostic procedure and is detected after the excision of the tumor, NS of the minor salivary glands may obscure an underlying neoplasm, resulting in delays in referral or treatment.

High PD-L1 expression in the tumour cells did not correlate with poor prognosis of patients suffering for oral squamous cells carcinoma: A meta-analysis of the literature.

OBJECTIVES: Oral cancer represents one of the most common malignancies in humans. Its prognosis is still poor, despite the most recent improvements in therapies. An increasing attention is placed on the role of programmed death ligand 1 (PD-L1) in the tumour immunity and its potential function as a marker for tumour prognosis. Whether PD-L1 expression is a prognostic factor for the poor outcomes in oral squamous cell carcinoma is still controversial. This study aimed to investigate, through a meta-analysis, a potential correlation between PD-L1 expression and the prognostic outcomes in patients with oral squamous cell carcinoma. MATERIALS AND METHODS: The studies were identified by searching PubMed, SCOPUS, Web of Science and were assessed by two of the authors. After the selection process, 11 articles met eligibility criteria and were included in the meta-analysis. Quality assessment of studies was performed according to the REMARK guidelines, and the risk of biases across studies was investigated through Q and I2 tests. Meta-analysis was performed to investigate the association between the PD-L1 expression either overall survival (OS), disease-free survival (DFS), disease-specific survival (DSS), gender and lymph node metastasis. RESULTS: A total of 1060 patients were analysed in the 11 studies included in the meta-analysis. Pooled analysis revealed that the expression of PD-L1 did not correlate with poor OS (HR, 0.60; 95% CI: [0.33, 1.10]; P = 0.10), DFS (HR, 0.62; 95% CI: [0.21, 1.88]; P = 0.40), DSS (HR, 2.05; 95% CI: [0.53, 7.86]; P = 0.29 and lymph node metastasis (HR, 1.15; 95% CI: [0.74, 1.81]; P = 0.53). Furthermore, results of the meta-analysis showed that high expression of PD-L1 is two times more frequent in female patients (OR, 0.5; 95% CI: [0.36, 0.69]; P < 0.0001) compared to males. For all the three outcomes analysed, a high rate of heterogeneity was detected (I2  > 50%). DISCUSSION: High PD-L1 expression did not correlate with poor prognosis of patients suffering for oral squamous cell carcinoma. Studies published on the topic showed a significant variation in results, limiting the use of PD-L1 expression by immunohistochemistry as prognostic biomarker in clinical practice.