[Current developments in primary and secondary surgical treatment of midface and periorbital trauma]. / Aktuelle Entwicklungen in der chirurgischen Primär- und Sekundärversorgung von Mittelgesichts- und periorbitalen Traumata.

Fractures of the periorbita and the midface are among the most common bony facial injuries. Aesthetic and functional reconstruction is a challenge in clinical routine. This article illustrates recent developments in the primary and secondary surgical treatment of midface and periorbital trauma. Resorbable patches and films increase the anatomic reconstructive capacity and enable treatment of extensive orbital fractures. Orbital fractures with involvement of supporting key structures are advantageously reconstructed using patient-specific implants (PSI), which are fabricated by computer-assisted manufacturing techniques and positioned by intraoperative navigation. If late complications such as bulbar malposition and enophthalmos have occurred after the initial procedure, they can be addressed by overcorrective restoration of orbital volume. The use of PSI for initial fracture restoration of the midface is not yet established but may be useful in re-osteotomies of misconsolidated fragments. Extensive midface defects with significant soft tissue involvement can be reconstructed using microvascular grafts. Consecutive reconstructive procedures may include orthognathic surgery and local flap reconstruction. In summary, the integration and advancement of computer-assisted techniques now offers individualized reconstruction procedures, which may be a viable alternative to conventional implants and compression miniplates. Future developments may focus on the search for innovative biomaterials, which can be integrated into computer-aided design and manufacturing processes.

Comparison of mucosal and mucoperiosteal wound cover for the treatment of medication-related osteonecrosis of the jaw lesions: a retrospective cohort study.

OBJECTIVES: Actually, there is no detailed guidance on how to deal with wound closure after surgical removal of medication-related osteonecrosis of the jaw (MRONJ) lesions. This study attempts to compare the difference in outcome between the mucosal and the mucoperiosteal flap closure after surgery. PATIENTS AND METHODS: In this retrospective monocentric cohort study, patients (n = 61; 35 female/26 male) suffering from MRONJ and requiring surgical therapy at the University of Aachen between 2013 and 2015 were included. Due to intra-institutional variances, one group was treated with the mucosal, the other group with the mucoperiosteal technique. The success rate, i.e., mucosal closure and no relapse at the point of follow-up, was evaluated and compared. All patients were clinically investigated for the postoperative follow-up during a special consultation appointment. RESULTS: The success rates between the different techniques after 2 years follow-up were very similar. In the group of mucosal wound closure, 22 of 29 (75.86%) patients revealed mucosal integrity without signs of MRONJ. The rate in the mucoperiosteal wound closure group was almost identical (24 of 32 (75%)). CONCLUSION: No differences in the success rates between the two different techniques could be evaluated. CLINICAL RELEVANCE: The results of this study suggest that the complete removal of the necrotic bone might have a higher impact on the success rates than the technique of the wound closure. Due to the fact that the mucoperiosteal wound closure technique offers a better overview of the extent of the MRONJ lesion, the authors advise to use this technique.

Direct biological effects of fractional ultrapulsed CO2 laser irradiation on keratinocytes and fibroblasts in human organotypic full-thickness 3D skin models.

Molecular effects of various ablative and non-ablative laser treatments on human skin cells-especially primary effects on epidermal keratinocytes and dermal fibroblasts-are not yet fully understood. We present the first study addressing molecular effects of fractional non-sequential ultrapulsed CO2 laser treatment using a 3D skin model that allows standardized investigations of time-dependent molecular changes ex vivo. While histological examination was performed to assess morphological changes, we utilized gene expression profiling using microarray and qRT-PCR analyses to identify molecular effects of laser treatment. Irradiated models exhibited dose-dependent morphological changes resulting in an almost complete recovery of the epidermis 5 days after irradiation. On day 5 after laser injury with a laser fluence of 100 mJ/cm2, gene array analysis identified an upregulation of genes associated with tissue remodeling and wound healing (e.g., COL12A1 and FGF7), genes that are involved in the immune response (e.g., CXCL12 and CCL8) as well as members of the heat shock protein family (e.g., HSPB3). On the other hand, we detected a downregulation of matrix metalloproteinases (e.g., MMP3), differentiation markers (e.g., LOR and S100A7), and the pro-inflammatory cytokine IL1α.Overall, our findings substantiate the understanding of time-dependent molecular changes after CO2 laser treatment. The utilized 3D skin model system proved to be a reliable, accurate, and reproducible tool to explore the effects of various laser settings both on skin morphology and gene expression during wound healing.

The safety of paediatric dentistry procedures under general anaesthesia. A five-year experience of a tertiary care center.

AIM: Frequently general anaesthesia (GA) is used to treat noncompliant children. Especially in children with morbid diseases general anaesthesia can be a challenging procedure for anaesthetists. The aim of this paper was to evaluate the risks and adverse reactions with a special focus on the impact of existing medication conditions and syndromes. MATERIALS AND METHODS: and methods Records of children up to 10 years of age, who were admitted for paediatric dentistry procedures under GA from January 2011 to December 2016 at the University Hospital of the University of Aachen (Germany), were reviewed. A special attention was paid to the intra- and perioperative critical adverse reactions and concomitant systemic conditions and their impact on treatment outcome. RESULTS: Two hundred and twenty patients were admitted for dental restorations. Critical adverse reactions occurred in 4% of the treated patients and they were statistically significantly (p=0.004) related to the ASA classification above II. The use of a laryngeal mask airway was significantly associated (p<0.001) with a shorter duration of surgery. Most common concomitant medical conditions were congenital heart disease, mental retardation and inherited syndromes. CONCLUSION: Although the administration of general anaesthesia in infants and children can be regarded as a safe procedure, clinically significant adverse reactions can occur, especially in patients with an existing medical condition.

Molecular effects of fractional ablative erbium:YAG laser treatment with multiple stacked pulses on standardized human three-dimensional organotypic skin models.

The molecular changes in gene expression following ablative laser treatment of skin lesions, such as atrophic scars and UV-damaged skin, are not completely understood. A standardized in vitro model of human skin, to study the effects of laser treatment on human skin, has been recently developed. Therefore, the aim of the investigation was to examine morphological and molecular changes caused by fractional ablative erbium:YAG laser treatment on an in vitro full-thickness 3D standardized organotypic model of human skin. A fractional ablative erbium:YAG laser was used to irradiate organotypic human 3D models. Laser treatments were performed at four different settings using a variety of stacked pulses with similar cumulative total energy fluence (60 J/cm2). Specimens were harvested at specified time points and real-time PCR (qRT-PCR) and microarray studies were performed. Frozen sections were examined histologically. Three days after erbium:YAG laser treatment, a significantly increased mRNA expression of matrix metalloproteinases and their inhibitors (MMP1, MMP2, MMP3, TIMP1, and TIMP2), chemokines (CXCL1, CXCL2, CXCL5, and CXCL6), and cytokines such as IL6, IL8, and IL24 could be detected. qRT-PCR studies confirmed the enhanced mRNA expression of IL6, IL8, IL24, CXCLs, and MMPs. In contrast, the mRNA expression of epidermal differentiation markers, such as keratin-associated protein 4, filaggrin, filaggrin 2, and loricrin, and antimicrobial peptides (S100A7A, S100A9, and S100A12) as well as CASP14, DSG2, IL18, and IL36ß was reduced. Four different settings with similar cumulative doses have been tested (N10%, C10%, E10%, and W25%). These laser treatments resulted in different morphological changes and effects on gene regulations. Longer pulse durations (1000 µs) especially had the strongest impact on gene expression and resulted in an upregulation of genes, such as collagen-1A2, collagen-5A2, and collagen-6A2, as well as FGF2. Histologically, all treatment settings resulted in a complete regeneration of the epidermis 3 days after irradiation. Fractional ablative erbium:YAG laser treatment with a pulse stacking technique resulted in histological alterations and shifts in the expression of various genes related to epidermal differentiation, inflammation, and dermal remodeling depending on the treatment setting applied. A standardized in vitro 3D model of human skin proved to be a useful tool for exploring the effects of various laser settings both on skin morphology and gene expression during wound healing. It provides novel data on the gene expression and microscopic architecture of the exposed skin. This may enhance our understanding of laser treatment at a molecular level.

[Squamous cell carcinoma as the most common oral carcinoma. Diagnosis and therapy]. / Plattenepithelkarzinom als das häufigste Mundhöhlenkarzinom. Diagnostik und Therapie.

BACKGROUND: About 5 % of all malignant tumors affect oral cavity. With a share of 95% squamous cell carcinoma is the most common type of the malignant tumors of oral mucosa. CASE REPORT: In our case the patient developed a squamous cell carcinoma of buccal mucosa about 2 years after excision of verrucous leukoplakia with epithelial dysplasia at the same location. Although chronic alcohol abuse, tobacco use and infection with HPV 16 are the most important risk factors for development of squamous cell carcinoma of the oral cavity, our patient had none of these risk factors. We treated the patient in accordance with current guidelines by complete excision of the tumor as well as an elective neck dissection of the ipsilateral side. Untill the present time the patient is free of recurrence. CONCLUSIONS: Although rare, squamous cell carcinoma of oral mucosa may also occur in patients that have no risk factors for it. Therefore, every dental and medical examination in each patient should include an inspection of the entire oral mucosa.

[Pyogenic granuloma of the oral mucosa]. / Granuloma pyogenicum der Mundschleimhaut.

Pyogenic granuloma is regarded as a vascular proliferation that may result from trauma or local irritation. The most common intraoral site is the gingiva, affected in 75 % of cases. Therapy of pyogenic granuloma consists of surgical excision. Recurrence after excision may occur. In our patient, there were no post-operative complications.

The impact and opportunities of large language models like ChatGPT in oral and maxillofacial surgery: a narrative review.

Since its release at the end of 2022, the social response to ChatGPT, a large language model (LLM), has been huge, as it has revolutionized the way we communicate with computers. This review was performed to describe the technical background of LLMs and to provide a review of the current literature on LLMs in the field of oral and maxillofacial surgery (OMS). The PubMed, Scopus, and Web of Science databases were searched for LLMs and OMS. Adjacent surgical disciplines were included to cover the entire literature, and records from Google Scholar and medRxiv were added. Out of the 57 records identified, 37 were included; 31 (84%) were related to GPT-3.5, four (11%) to GPT-4, and two (5%) to both. Current research on LLMs is mainly limited to research and scientific writing, patient information/communication, and medical education. Classic OMS diseases are underrepresented. The current literature related to LLMs in OMS has a limited evidence level. There is a need to investigate the use of LLMs scientifically and systematically in the core areas of OMS. Although LLMs are likely to add value outside the operating room, the use of LLMs raises ethical and medical regulatory issues that must first be addressed.

Accuracy and clinical outcomes of mandibular reconstruction with a virtually planned deep circumflex iliac artery flap with stock temporomandibular joint prosthesis.

The repair of hemimandibulectomy defects involving the temporomandibular joint (TMJ) is challenging. This study compared the functional outcomes and reconstruction accuracy using a deep circumflex iliac artery (DCIA) flap with and without a virtually planned stock TMJ prosthesis (TMJP) after hemimandibulectomy. Ten patients were assessed: five with a TMJP (TMJP group) and five without (control group). A three-dimensional comparison revealed a mean deviation of 0.11 ± 0.04 mm between the planned and actual DCIA flap with TMJP. The planned and actual TMJP positions differed by 0.56 ± 0.57 mm in height, 0.33 ± 0.24 mm ventrally/dorsally, and 1.18 ± 0.42 mm medially/laterally. Mouth opening, laterotrusion, and midline deviation were significantly greater in the control group than in the TMJP group (P = 0.024, P = 0.008, P = 0.024). The deviation in ventral to dorsal translation for the DCIA flap was slightly higher than reported values in the literature, while height deviation was comparable. Lower deviations in the literature were due to the DCIA flap being used where both TMJs were intact. The in-house virtually planned DCIA flap with stock TMJP yielded results comparable to more expensive patient-specific prostheses.

Defining biomechanical principles in pre-surgical infant orthopedics in a real cleft finite element model.

Presurgical infant orthopedics (PSIO) is the first step in the treatment of cleft lip and palate (CLP) and is designed to approximate the cleft segments as effectively as possible before surgical reconstruction of the lip and palate. The biomechanical efficacy of different PSIO approaches in transferring molding forces to the CLP is unknown. This study aimed to define the biomechanical principles of competing PSIO techniques in a real cleft finite element (FE) model. Active intraoral (Latham), passive alveolar molding (PAM), and extraoral (DynaCleft) molding forces were virtually applied to a real cleft FE model. In the cleft region, PAM (P < 0.001) and Latham (P < 0.05) exerted significantly less stress than DynaCleft. Intraoral molding forces acted primarily at the site of the force initiation without being accompanied by high loads in the midface. PAM showed a tendency toward a better flow behavior of the molding forces than Latham. Extraoral molding transferred high stresses to the cleft, alveolar ridge, and midface. Intraoral passive molding was ultimately characterized by the highest biomechanical efficacy and showed the most favorable load distribution of all of the PSIO approaches considered in this study. Future research is needed to validate the findings against clinical data.

A cadaveric study of induced isolated orbital floor fractures and implications for surgical decision-making: comparison of two preoperative imaging modalities.

Computed tomography (CT) is the gold standard for the diagnosis of isolated orbital floor fractures, while cone beam computed tomography (CBCT) is an alternative. The aim of this study was to compare the diagnostic accuracy of CT and CBCT for isolated orbital floor fractures. Forty-eight isolated orbital floor fractures were systematically induced in cadaver orbits. CBCT and CT scans of each cadaver head were performed and the image data imported into ProPlan CMF for analysis. The orbital floor area (OFA), orbital defect area (ODA), and peri-orbital tissue herniation were evaluated. Surgical decision-making differed significantly according to the imaging modality (P = 0.031). The odds of decision discrepancy between CBCT and CT were higher with increasing ODA/OFA ratios, when adjusted for peri-orbital tissue herniation and fracture localization (P = 0.026). An ODA/OFA ratio cut-off value of >36.25% had a sensitivity of 100% and specificity of 71% (area under the curve 0.83, P = 0.011) for predicting discrepancies between CBCT and CT in surgical decision-making. In this cadaveric study, CT and CBCT were diagnostically equivalent for isolated orbital floor fractures with an ODA/OFA ratio ≤36.25%. However, fractures exceeding this threshold may be better evaluated by CT to avoid discrepancies in surgical decision-making.

Immune checkpoint analysis in ear cancer.

BACKGROUND: Among cutaneous squamous cell carcinomas, the ear (ecSCC) is one of the most common sites. Loco regional lymph node metastasis is found in six to eleven percent of cases, corresponding to increased metastasis compared to other sites. The aim of this study was to test the markers PD-L1, PD-1, CD4, CD8, and FoxP3 for suitability as prognostic predictive markers. METHODS: Sixty-four patients with ecSCC were included in this study. The expression of immunohistochemical markers (PD-L1, PD-1, CD4, CD8, FOXP3) was correlated with retrospective clinic pathological parameters (lymph node metastasis, distant metastasis, lymph node metastasis during follow-up, disease progression, disease-specific death). RESULTS: There was a correlation between increased disease specific death and a weak Foxp3 (p = 0.003) or reduced CD8 (p = 0.04). A PD-L1 expression > 1% was found in 39.1% of patients. CONCLUSION: The investigated markers (CD4, CD8, FoxP3, PD-1, PD-L1) seem overall rather inappropriate for prognostic evaluation in ecSCC. Only the correlation of disease specific death with CD8 or FoxP3 seems to be worth testing in larger collectives.

Perfusion of microvascular free flaps in head and neck reconstruction after prior neck dissection and irradiation.

Microvascular free flaps are frequently used for head and neck reconstruction after prior neck dissection (ND) and neck irradiation (RTX). The aim of this study was to investigate the influence of ND and RTX on flap perfusion as a critical factor for flap success. Overall, 392 patients reconstructed with a microvascular fasciocutaneous flap (FF) or perforator flap (PF) in the head and neck region between 2011 and 2020 were analysed retrospectively. Flap perfusion measured intraoperatively and postoperatively with the O2C tissue oxygen analysis system was compared between patients who had received neither ND nor RTX (controls), patients who had received ND but no RTX (ND group), and patients who had received both ND and RTX (ND+RTX group). Intraoperative and postoperative flap blood flow was decreased in FFs in ND group patients compared to controls (median 66.3 AU vs 86.0 AU, P = 0.023; median 73.5 AU vs 93.8 AU, P = 0.045, respectively). In the multivariable analysis, these differences showed a tendency to persist (P = 0.052 and P = 0.056). Flap success rates were similar in control patients, ND patients, and ND+RTX patients (98.7%, 94.0%, and 97.6%, respectively). Flap perfusion is not reduced in FFs and PFs in patients who have undergone ND or ND and RTX. This indicates that neck dissection and neck irradiation should not be contraindications for microvascular free flap reconstruction.

Evaluation of anterolateral thigh flap dimensions with virtual flap models.

Free flaps are commonly used for head and neck reconstruction. However, flap dimensions are still evaluated by visual and tactile assessment. The aim of this study was to enable preoperative planning of flap dimensions for soft tissue reconstruction based on clinical parameters. Computed tomography records from 230 patients dated from 2009 to 2019 were analysed retrospectively. A virtual, three-dimensional anterolateral thigh flap model was standardized, aligned to segmented leg models in two positions, and flap thicknesses and volumes were determined. Associations of flap thickness and volume with clinical parameters were evaluated, and an approximative calculation method was derived. The laterally positioned anterolateral thigh flap showed an average (interquartile range) thickness of 15.6 mm (8.7 mm) and volume of 1.5 cm3 (0.9 cm3) per cm2. The medially positioned anterolateral thigh flap showed an average (interquartile range) thickness of 16.3 mm (8.7 mm) and volume of 1.6 cm3 (0.9 cm3) per cm2. For both flap positions, leg circumference was the strongest predictor of flap thickness (ß = 0.545, P < 0.001 and ß = 0.529, P < 0.001) and flap volume (ß = 0.523, P < 0.001 and ß = 0.480, P < 0.001). Flap dimensions can be calculated based on leg circumference, and this preoperative planning of flap dimensions can help the surgeon to select the appropriate flap.

Identification of risk factors for postoperative delirium in patients following intraoral reconstruction with microvascular free flaps: a matched-pair analysis.

Postoperative delirium (POD) following microvascular head and neck reconstruction negatively impacts patient outcomes, and only a few risk factors have been identified. The aim of this study was to identify additional risk factors for POD after intraoral reconstruction with microvascular free flaps. Data from 377 patients who underwent intraoral microvascular free flap reconstruction between 2011 and 2019 were analysed retrospectively. Preoperative, intraoperative, and postoperative variables were compared between 40 patients with POD and 40 patients without POD who were matched for previously identified risk factors (i.e., sex, age, American Society of Anesthesiologists class, preoperative arterial hypertension, tracheotomy, operation time, and blood transfusion). A multivariable regression analysis was then performed to identify risk factors associated with POD. POD occurred in 50 (13.3%) of the 377 cases studied; the median time of onset was postoperative day 2. Excessive preoperative alcohol consumption (odds ratio 9.22, 95% confidence interval 1.09-77.97; P = 0.041) and postoperative transplant revision (odds ratio 25.72, 95% confidence interval 1.26-525.43; P = 0.035) were identified as risk factors for POD. The identification of patients at high risk of POD based on these two risk factors may allow early adjustment of diagnostic and therapeutic modalities to improve outcomes and reduce healthcare costs.

Evaluation of fibrin, cyanoacrylate, and polyurethane-based tissue adhesives in sutureless vascular anastomosis: a comparative mechanical ex vivo study.

The stability of a microvascular anastomosis is an important prerequisite for successful tissue transfer. Advances in tissue adhesives are potentially opening new avenues for their use in sutureless microsurgical anastomosis, however they have not yet gained clinical acceptance. In this ex vivo study, a novel polyurethane-based adhesive (PA) was used in sutureless anastomoses and its stability compared with that of sutureless anastomoses performed with fibrin glue (FG) and a cyanoacrylate (CA). Stability was assessed using hydrostatic (15 per group) and mechanical tests (13 per group). A total of 84 chicken femoral arteries were used in this study. The time taken to create the PA and CA anastomoses was significantly faster when compared to the FG anastomoses (P < 0.001): 1.55 ± 0.14 min and 1.39 ± 0.06 min, respectively, compared to 2.03 ± 0.35 min. Both sustained significantly higher pressures (289.3 mmHg and 292.7 mmHg, respectively) than anastomoses using FG (137.3 mmHg) (P < 0.001). CA anastomoses (0.99 N; P < 0.001) and PA anastomoses (0.38 N; P = 0.009) could both withstand significantly higher longitudinal tensile forces compared to FG anastomoses (0.10 N). Considering the background of an in vitro study, the PA and CA anastomosis techniques were shown to be similar to each other and superior to FG, due to their stability and faster handling. These findings need to be validated and confirmed in further in vivo studies.

Evaluation of a new optical measuring system for experiments on fractured human mandibles: a biomechanical feasibility study in maxillofacial surgery.

OBJECTIVES: Biomechanical loading on human mandibles was performed and a new optical measurement device was introduced for the quantification of interfragmentary movement in fractured mandibles stabilized with different osteosynthesis systems. MATERIALS AND METHODS: Comparison tests were performed with monocortical non-locking double plates and bicortical single locking plate. For the experiments on a specialized test bench, 18 ex vivo fractured human cadaveric mandibles were tested. Interfragmentary motion was detected in all three spatial dimensions using the optical measurement device PONTOS®. The movement was investigated over increasing incisal force and one summarized parameter was investigated. RESULTS: For the maximal tested load of 300 N m, the resultant interfragmentary movements in the two investigated groups were 2.96 ± 1.85° for the fixation with two conventional miniplates (six hole, profile 1.0 mm) and 4.53 ± 2.49° for single bicortically fixed locking plates (four hole, profile 1.5 mm). For both plate systems, we used the 2.0 mm screw system. CONCLUSIONS: The test bench in combination with the new optical device PONTOS(®) can test the primary stability of osteosynthesis. We offer a solution to the problem of rate of twist of the mandible as well as typical rotational problem in recent measurements. Further, the method can be used for development of new osteosynthesis products. CLINICAL RELEVANCE: Pseudoarthrosis formation is a common problem based on unsatisfying fixation of the fracture gap. The here presented combination of mechanical tests and numerical simulations can provide support for an improved treatment of fractured mandibles.

[Hemangiopericytoma of the buccal mucosa. A case report]. / Hämangioperizytom der Wange. Ein Patientenbeispiel.

Hemangiopericytoma describes a rare mesenchymal neoplasm which can occur at any site on the body and represents 1% of vascular tumors. Histologically, it is characterized by a vascular pattern with high cellularity. These tumors occur in particular near the torso and surface variants are rare. Due to the unspecific clinical picture, it is often confused with other benign mesenchymal tumors. The heterogenous course and high risk of recurrence with hemangiopericytomas necessitate long-term clinical follow-up.

The primary stability of two dental implant systems in low-density bone.

Primary stability in low-density bone is crucial for the long-term success of implants. Tapered implants have shown particularly favourable properties under such conditions. The aim of this study was to compare the primary stability of tapered titanium and novel cylindrical zirconia dental implant systems in low-density bone. Fifty implants (25 tapered, 25 cylindrical) were placed in the anterior maxillary bone of cadavers meeting the criteria of low-density bone. The maximum insertion (ITV) and removal (RTV) torque values were recorded, and the implant stability quotients (ISQ) determined. To establish the isolated influence of cancellous bone on primary stability, the implantation procedure was performed in standardized low-density polyurethane foam bone blocks (cancellous bone model) using the same procedure. The primary stability parameters of both implant types showed significant positive correlations with bone density (Hounsfield units) and cortical thickness. In the cadaver, the cylindrical zirconia implants showed a significantly higher mean ISQ when compared to the tapered titanium implants (50.58 vs 37.26; P < 0.001). Pearson analysis showed significant positive correlations between ITV and ISQ (P = 0.016) and between RTV and ISQ (P = 0.035) for the cylindrical zirconia implants; no such correlations were observed for the tapered titanium implants. Within the limitations of this study, the results indicate that cylindrical zirconia implants represent a comparable viable treatment option to tapered titanium implants in terms of primary implant stability in low-density human bone.

The effect of zirconia and titanium surfaces on biofilm formation and on host-derived immunological parameters.

The aim of this study was to analyse the effect of zirconia and titanium surfaces on biofilm formation and host-derived parameters. Studies comparing zirconia and titanium surfaces were selected up to September 1, 2019. The outcome measures were surface roughness, contact angle, bacterial count, bacterial adherence, biofilm thickness, bacterial distribution, and specifically investigated biofilm and specific host-derived immunological parameters. Random-effects meta-analyses of in vitro and in vivo studies were conducted. A total of 39 studies were included for data extraction. In the systematic review data, 10 studies stated that zirconia accumulated less initial oral biofilm parameters, 16 investigations showed negligible inter-material differences, and only one study showed that zirconia attracted the most biofilm. However, in the meta-analysis, the bacterial coverage was found to be significantly superior for zirconia surfaces (P< 0.00001); the other outcome measures did not show any statistically significant differences between zirconia and titanium for the remaining parameters and the studies presented a substantial degree of heterogeneity. Overall, on the basis of the meta-analysis, the current data situation does not allow a clear preference for the use of zirconia or titanium.