Testing the effects of photobiomodulation on angiogenesis in a newly established CAM burn wound model.

Burn wounds are a common challenge for medical professionals. Current burn wound models hold several limitations, including a lack of comparability due to the heterogeneity of wounds and differences in individual wound healing. Hence, there is a need for reproducible in vivo models. In this study, we established a new burn wound model using the chorioallantoic membrane assay (CAM) as a surrogate model for animal experiments. The new experimental setup was tested by investigating the effects of the auspicious biophysical therapy, photobiomodulation (PBM), on the wound healing of an induced CAM burn wound with a metal stamp. PBM has been shown to positively influence wound healing through vascular proliferative effects and the increased secretion of chemotactic substances. The easily accessible burn wounds can be treated with various therapies. The model enables the analysis of ingrowing blood vessels (angiogenesis) and diameter and area of the wounds. The established model was used to test the effects of PBM on burn wound healing. PBM promoted angiogenesis in burn wounds on day 4 (p = 0.005). Furthermore, there was a not significant trend toward a higher number of vessels for day 6 (p = 0.065) in the irradiated group. Changes in diameter (p = 0.129) and the burn area (p = 0.131) were not significant. Our results suggest that CAM can be a suitable model for studying burn wounds. The novel experimental design enables reproducible and comparable studies on burn wound treatment.

Effect of Low-level Light Therapy on Post-operative Healing of Secondary Chronic Osteomyelitis of the Jaws - A Prospective Study.

Introduction: Osteomyelitis of the jaws is a common disease of the maxillofacial region. The goal of treatment is to alleviate pain, reduce infection, inhibit the progression of the disease and induce bone and mucosal healing. In addition to surgical management and antibiotic and oxygen hyperbaric therapy, new therapeutic strategies for the treatment of osteomyelitis are developed. One of the novel approaches is photobiomodulation therapy or low-level light therapy (LLLT). Materials and Methods: After surgical treatment, experimental group patients (n = 4) were treated with LLLT for five sessions with an extraoral pulsed 635-nm LED lamp (Repuls7, Repuls Lichtmedizintechnik GmbH, Austria), maximum output power: 140 mW/cm2, frequency: 2.5 Hz, duty cycle: 50%. Clinical achievement and patient pain perception (through Visual Analogue Scale score) were evaluated at 1-, 3- and 6-month follow-up appointments and compared with control group (n = 4) patients, treated with standard therapy. Results: At three and six months, clinical achievement was better in patients treated with LLLT. Pain and discomfort resolution was significantly greater in the experimental group. Discussion: Taking into consideration the results of this study, it can be concluded that LLLT shows potential for improving clinical outcome of surgical and medical treatment of secondary chronic osteomyelitis of the jaws. Furthermore, pain and discomfort were significantly reduced in patients treated with LLLT. Further research with a larger sample size is needed to obtain a more accurate insight into this promising field.

A Novel Artificial Intelligence-Based Approach for Quantitative Assessment of Angiogenesis in the Ex Ovo CAM Model.

Angiogenesis is a highly regulated process. It promotes tissue regeneration and contributes to tumor growth. Existing therapeutic concepts interfere with different steps of angiogenesis. The quantification of the vasculature is of crucial importance for research on angiogenetic effects. The chorioallantoic membrane (CAM) assay is widely used in the study of angiogenesis. Ex ovo cultured chick embryos develop an easily accessible, highly vascularised membrane on the surface. Tumor xenografts can be incubated on this membrane enabling studies on cancer angiogenesis and other major hallmarks. However, there is no commonly accepted gold standard for the quantification of the vasculature of the CAM. We compared four widely used measurement techniques to identify the most appropriate one for the quantification of the vascular network of the CAM. The comparison of the different quantification methods suggested that the CAM assay application on the IKOSA platform is the most suitable image analysis application for the vasculature of the CAM. The new CAM application on the IKOSA platform turned out to be a reliable and feasible tool for practical use in angiogenesis research. This novel image analysis software enables a deeper exploration of various aspects of angiogenesis and might support future research on new anti-angiogenic strategies for cancer treatment.

First-in-man application of a cold ablation robot guided laser osteotome in midface osteotomies.

The aim of the study was to assess the clinical applicability of robot guided laser osteotomy for clinical application. This is the initial report on 14 consecutive patients requiring an orthognathic procedure with a midface osteotomy (no restrictions made on the surgical indication itself) who have undergone surgery by means of the Cold Ablation Laser Osteotome CARLO® (AOT Advanced Osteotomy Tools, Basle, Switzerland), which is an integrated system, functionally comprising: an Er:YAG laser source, intended to perform osteotomies using cold laser ablation, a robot arm that controls the position of the laser source, an optical tracking device that provides a continuous and accurate measurement of the position of the laser source and of reference elements attached to instruments or bones, a navigation system (software) that is able to read preoperatively defined planned osteotomies, and - under the control of a surgeon - performs the planned osteotomies. Safety was assessed by unimpaired postoperative healing and the absence of device related injuries; performance was assessed as ability to cut the maxilla along the preoperatively planned cutting path with a rage of accuracy of 2mm. Cold ablation robot-guided laser osteotomy could successfully be performed in 14 consecutive patients. No intraoperative complications or technical failure occurred. All osteotomies were within an average deviation of 0.80 mm (±0.26 mm) of the virtually preplanned location. The registration procedure to set up the robot at the beginning of the operation required a mean time of 4.6 min (±5.3min). In this report we describe the effective and successful routine use of Cold ablation robot-guided laser osteotomy in an actual clinical setting. It is a promising technical innovation that has the potential to set new standards for accuracy and safety in orthognathic surgery.

Accuracy of Soft Tissue Prediction of 2 Virtual Planning Systems in Patients Undergoing Intraoral Quadrangular Le Fort II Osteotomy.

Virtual surgical planning (VSP) is state of the art in routine clinical work. Visualization of soft tissue changes adds important information for surgical planning. The aim of this study was to evaluate accuracy of soft tissue prediction of 2 VSP systems in patients undergoing an intraoral quadrangular Le Fort II osteotomy. METHODS: VSP was performed with the software application IPS Case Designer (IPS) and Dolphin Imaging 11.95 (DOL) in bone and soft tissue structure. Distances were measured at the 3 levels of the face at the infraorbital rim, the sinus floor, and the lateral incisor level with 2 VSP systems (DOL and IPS). RESULTS: A convenience sample of 19 patients was included in the study with a mean age of 21.9 years. From cranial to caudal, mean differences between simulation and postintervention data were as follows: infraorbital rim level: DOL and ST0: mean difference: 2.90 mm; IPS and ST0: 1.70 mm; sinus floor level: DOL and ST0: mean difference: 3.57 mm; IPS and ST0: 1.34 mm; and lateral incisor level: DOL and ST0: mean difference: 2.48 mm; IPS and ST0: 2.25 mm. CONCLUSIONS: Generally, both VSP systems are suitable for planning an intraoral quadrangular Le Fort II osteotomy. Especially in the infraorbital region, improvement of the algorithm is required for trustworthy prediction of soft tissue changes.

Comparison of feasibility, time consumption and costs of three virtual planning systems for surgical correction of midfacial deficiency.

BACKGROUND: Today virtual surgical planning (VSP) is a standard method in maxillofacial corrective surgery and is the key to reach satisfactory esthetic outcomes. The purpose of this study was to evaluate usability of three established virtual surgical planning software applications by comparing feasibility, time consumption, and costs in a standardized workflow for a modified intraoral quadrangular Le Fort II osteotomy (IQLFIIO). RESULTS: A cross-sectional study was performed based on retrospective and re-planned data of patients with midfacial deficiency treated by modified IQLFIIO, using three software applications: IPS Case Designer ®, Dolphin Imaging ®, and ProPlan CMF ®. Feasibility: All evaluated steps of the VSP procedure could be successfully performed in all three evaluated applications. In all software packages, it was possible to design the surgical splints with CAD/CAM technology. Working time: The mean value of time needed was IPS Case Designer ®, 36.5 min; Dolphin Imaging ®, 33.6 min; ProPlan CMF ®, 45.5 min. We found statistical significant difference between ProPlan CMF ® and Dolphin Imaging ® (p value, 0.02). COSTS: Asset costs for acquiring the software, license fee, license possibilities, paying for support services, and service contracts were evaluated and are found in similar ranges. CONCLUSION: All three tested software applications are usable for virtual planning of an IQLFIIO and splint production by CAD/CAM technology. Successful movement of bone segments and overlaying soft tissues proved feasibility. Time consumption and costs were found in similar ranges.

The Effect of Low-Level Light Therapy on Capsaicin-Induced Peripheral and Central Sensitization in Healthy Volunteers: A Double-Blinded, Randomized, Sham-Controlled Trial.

INTRODUCTION: Several clinical trials have demonstrated that low-level light therapy (LLLT), a method of photobiomodulation, is an effective analgetic treatment. However, the mechanism of action has not yet been finally clarified. In particular, unanswered questions include whether it only affects peripheral or whether it also affects the spinal or supraspinal level. This study aimed to evaluate the effect of low-level light therapy on primary and secondary hyperalgesia in a human pain model. METHODS: This study was planned as a randomized, sham-controlled, and double-blinded trial with repeated measures within subject design. Capsaicin was applied on both forearms of ten healthy volunteers to induce peripheral and central sensitization. One forearm was treated with low-level light therapy; the other served as sham control. RESULTS: Low-level light therapy significantly increased the mechanical pain threshold, heat pain threshold, and decreased pain intensity. CONCLUSIONS: Our data indicate that low-level light therapy is effective at reducing the heat and mechanical pain threshold in a human pain model, pointing to a significant modulating effect on peripheral and central sensitization. These effects-especially in the absence of reported side effects-make low-level light therapy a promising tool in pain management. The application of low-level light therapy to treat chronic pain should be considered for further clinical trials.

Changes of temporomandibular joint position after surgery first orthognathic treatment concept.

Orthognathic surgery treatment (OGS) after orthodontic treatment of dentofacial deformities is a widely performed procedure, often accompanied by a bilateral sagittal split osteotomy (BSSO). Positioning of the condyle during this procedure is a crucial step for achieving optimal functional and anatomical results. Intraoperatively poorly positioned condyles can have a negative effect on the postoperative result and the patient's well-being. Changes of the condylar position during OGS Procedures and its effects on the temporomandibular joint in orthognathic surgical interventions (OGS) are subject of scientific discussions. However, up to date, no study has investigated the role of condyle position in the surgery first treatment concept. The aim of this study was to investigate the influence of OGS on the three-dimensional position of the condyle in the joint in a surgery first treatment concept without positioning device and to record the change in position quantitatively and qualitatively. Analysis of our data indicated that OGS in surgery first treatment concept has no significant effect on the position of the condyle and the anatomy of the temporomandibular joint.

Photobiomodulation (PBM) promotes angiogenesis in-vitro and in chick embryo chorioallantoic membrane model.

The application of light in various therapeutic settings known as Photobiomodulation (PBM) is well established. Indications are the improvement of wound healing and tissue regeneration, scarring, and perfusion as well as pain therapy. Tissue perfusion is mandatory for successful wound healing. Nevertheless, there is a lack of mechanistic studies. We investigate the potential effect of PBM from light emitting diodes (LED) at 635 nm, 80 mW/cm2, 24 J/cm2 on angiogenesis in a two-part study: 1.) Investigation of the effect of PBM on the proliferation of endothelial cells and on vasculogenesis in a co-culture model of endothelial cells and stem cells. 2.) Investigation of the influence of PBM at chick egg chorioallantoic membrane (CAM) assays with fresh human skin xenografts. In both study phases, we observed a stimulating effect of PBM at 635 nm; in part 1: for proliferation of HUVEC (human umbilical vein endothelial cells) (25833 ± 12859 versus 63002 ± 35760 cells/well, p < 0.05, for cellular network formation (2.1 ± 2.1 versus 4.6 ± 3.5, p < 0.05) and for less cell compactness p = 0.01; in part 2: for the increase of number of vessel junctions per ROI (region of interest) (15.9 ± 2.6 versus 20.8 ± 5.4, p < 0.05). Our results suggest significant promotion of angiogenesis by PBM at 635 nm in vitro and in vivo.

Accuracy of soft tissue prediction in surgery-first treatment concept in orthognathic surgery: A prospective study.

PURPOSE: The purpose of this study was to provide a quantitative accuracy assessment of soft tissue predictions generated by a computer-aided maxillofacial planning system in patients undergoing orthognathic surgery following the "surgery-first" treatment. MATERIALS AND METHODS: For this study, we looked at 16 patients with open bite dentofacial-dysmorphosis who underwent orthognathic surgery. Surgeries were planned using conventional sketches and the newly developed computer-assisted SOTIRIOS planning software (developed by the authors). Validation procedures were performed in the following steps: (1) Standardized registration of the pre- and postoperative CT volumes; (2) Automated adjustment of the bone-related preoperative planning to the actual postoperative bony displacement; (3) Simulation of soft tissue changes according to the definitive bony movements; and (4) Calculation of soft tissue differences between the predicted and the actual 6-month postoperative results by distance mapping. RESULTS: The program produced a clinically satisfactory 3D soft tissue prediction, with a mean error of 1.46 mm ± 1.53 mm. The program was suitable for use in virtual surgical planning without technical assistance. CONCLUSION: This study shows that the program is quite accurate, enabling the surgeon to predict the outcome of the soft tissue. This has the potential to promote the routine application of the surgery-first approach in patients suffering from open bite.

Soft Tissue Changes in Patients Undergoing Intraoral Quadrangular Le Fort II Osteotomy Versus Conventional Le Fort I Osteotomy.

PURPOSE: The aim of this study was to evaluate soft tissue changes after intraoral quadrangular Le Fort II osteotomy (IOQLFII) and correlate those changes to underlying osseous changes. MATERIALS AND METHODS: Twenty-six non-growing patients with midfacial deficiency and Class III malocclusion were analyzed. A study group of 13 patients who underwent IOQLFII was compared with 13 patients who underwent conventional Le Fort I osteotomy (LFI). After fusion of pre- and postoperative computed tomograms, each patient's hard and corresponding soft tissue changes were measured. Measurement points were defined at 3 levels in the IOQLFII group (infraorbital rim [IR], sinus floor [SF], and lateral incisor tip [LI]) and at 2 levels in the LFI group (SF and LI). Linear models were created to test for correlations between hard and soft tissues. RESULTS: The slope (a1 coefficient) between anteroposterior hard and soft tissue changes was found to be highly significant at each measurement point for all groups. In the IOQLFII group, soft tissue advancement was 69% (confidence interval [CI], 62 to 77%) of the hard tissue advancement at the IR, 90% (CI, 84 to 96%) at the SF, and 73% (CI, 64 to 82%) at the LI. In the LFI group, the corresponding percentages were 90% (83 to 97%) at SF and 84% (77 to 90%) at LI. CONCLUSION: IOQLFII results in predictable correction of midfacial deficiency. At the IR, bony advancement always resulted in markedly less soft tissue advancement than at the SF level. These results indicate that the planned infraorbital advancement should not be too conservative because soft tissue changes are smaller in this region.

Evaluation of an experimental oblique plate for osteosynthesis of mandibular condyle fractures.

OBJECTIVE: The aim of this study was to test the bone thickness and potential screw length for osteosynthesis of condylar base fractures (according to the Loukota classification) with an experimental titanium plate, placed in an ideal position against 2 types of conventional plates. STUDY DESIGN: After exclusion of completely edentulous mandibles, 28 dentate macerated mandibles available at the time of the study were included. Linear regression models 1 and 2 compared the sums of the 2 cranial bone thicknesses and the 3 caudal thicknesses among the 3 different plate designs, and linear models 3 and 4 tested the bone thickness in the 2 most cranial screw axes. RESULTS: Linear models 1 and 2 revealed significantly higher potential screw lengths for the experimental oblique plate. Equally, linear models 3 and 4 indicated significantly higher bone thickness for the novel oblique plate. CONCLUSION: The novel proposed oblique plate allows for favorable plate positioning in a biomechanically ideal location with sufficient amounts of local bone for stable plate fixation. When plates with 15-degree angulated screw holes are used, stable bicortical plate fixation can be achieved.

Morphometric analysis of sinus depth in the posterior maxilla and proposal of a novel classification.

The aim of this study was to analyse the posterior maxillary sinus based on its extension into the alveolar process and to provide a simple clinical classification. A retrospective cohort study was conducted in CT scans of 200 dentate and 200 edentulous patients (100 women and 100 men, respectively). After manual placement of 12 reference points morphometric analysis was performed and sinus depth, residual alveolar ridge height (RH) and the sinus opening angle were calculated. Sinuses were classified according to the quartiles of sinus depth: class I (above the hard palate), class II (0-6 mm below the hard palate) and class III (>6 mm below the hard palate). Sinus depth was found to be a reliable anatomical landmark and did not vary significantly between gender (p = 0.8940) or dentition groups (p = 0.9723). Alveolar height varied significantly between sinus classes (p < 2 × 10-16) and dentition groups (p < 2 × 10-16) but not between genders (p = 0.5178). The sinus opening angle was significantly different between sinus classes (p < 2.2 × 10-16) but not between gender or dentition groups. We propose a novel classification built upon the quartiles of sinus depth, dividing the sinuses into three classes. Our classification is the first one that represents the anatomy of the patient independent of gender and dentition.

The frequency of dental abscesses increases in periods of low barometric pressure.

Bioclimatic conditions are thought to have an impact on the frequency of dental abscesses but previous studies have suffered from small patient cohorts, methodological obstacles, and restriction to a single site resulting in limited geographic and meteorological variability. The aim of the present study was to investigate the influence of environmental temperature and barometric pressure on the frequency of dental abscesses. Three maxillofacial and two dental clinics in Vienna retrospectively provided a total of 19,218 patients with dentoalveolar abscesses who were treated by intraoral incision between 1998 and 2011. Daily records from six local meteorological stations were consulted to assess daily meteorological parameters. Univariate and multivariate hurdle count regression models were fitted to estimate the effect of daily average barometric pressure and temperature on registered abscess frequencies. Temporal confounders causing variance of the observed abscess frequencies - such as weekday, business day, and month - were taken into consideration. On days of low barometric pressure a significant rise in dental abscess frequency was observed, even when adjusting for confounders. Environmental temperature, in contrast, did not show any effect. In conclusion, bioclimatic conditions affect health as low barometric pressure increases the number of patients with dental abscesses.

Assessment of Artificial Teeth Setup Device: A Three-Dimensional Model Analysis.

This study assessed the use of the commercial artificial teeth setup device Staub Cranial System (Neu-Ulm) in Asian subjects. Fourteen completely dentate Thai volunteers were randomly recruited. Study casts (control group) and duplicated casts (experimental group) of all subjects were prepared. Artificial teeth were replaced on duplicated casts according to the manual. Computed tomography scans of all casts were performed. Intercanine width, intermolar width, incisocervical length, and occlusal plane were investigated. The length of the natural mandibular left central incisor was smaller than the reconstructed one. The reconstructed occlusal plane was more parallel to the hamular-incisive papilla plane than that of the control group.

Optical coherence tomography for planning of follicular unit extraction.

BACKGROUND: As the subcutaneous course of the hair follicle cannot be extrapolated from the angle of hair emergence, the follicular unit extraction (FUE) method bears the risk of follicle transsection potentially affecting the success of the whole intervention. Histological examination can provide this angle information but are too time consuming and invasive to be integrated in the workflow. OBJECTIVE: In this work, the authors present an effective and noninvasive way to determine these subcutaneous follicle angles. METHODS AND MATERIALS: For this purpose, the authors use optical coherence tomography to provide images of the first 2 to 3 mm of the surface of the skin. RESULTS: On 3 probands, they scanned 2 regions. We computed the number of hair follicles in a certain angular region around a mean angle, representing an FUE tool, and found a considerable diversity of the angular deviations. CONCLUSION: As this angular distribution massively influences the transsection rate, the authors suggest such a method to be considered as a future improvement of preoperative assessment.

Patient-specific polyetheretherketone facial implants in a computer-aided planning workflow.

PURPOSE: In the present study, we report an innovative workflow using polyetheretherketone (PEEK) patient-specific implants for esthetic corrections in the facial region through onlay grafting. The planning includes implant design according to virtual osteotomy and generation of a subtraction volume. The implant design was refined by stepwise changing the implant geometry according to soft tissue simulations. MATERIALS AND METHODS: One patient was scanned using computed tomography. PEEK implants were interactively designed and manufactured using rapid prototyping techniques. Positioning intraoperatively was assisted by computer-aided navigation. Two months after surgery, a 3-dimensional surface model of the patient's face was generated using photogrammetry. Finally, the Hausdorff distance calculation was used to quantify the overall error, encompassing the failures in soft tissue simulation and implantation. RESULTS: The implant positioning process during surgery was satisfactory. The simulated soft tissue surface and the photogrammetry scan of the patient showed a high correspondence, especially where the skin covered the implants. The mean total error (Hausdorff distance) was 0.81 ± 1.00 mm (median 0.48, interquartile range 1.11). The spatial deviation remained less than 0.7 mm for the vast majority of points. CONCLUSIONS: The proposed workflow provides a complete computer-aided design, computer-aided manufacturing, and computer-aided surgery chain for implant design, allowing for soft tissue simulation, fabrication of patient-specific implants, and image-guided surgery to position the implants. Much of the surgical complexity resulting from osteotomies of the zygoma, chin, or mandibular angle might be transferred into the planning phase of patient-specific implants.

Causes and timing of delayed bleeding after oral surgery.

OBJECTIVES: This study examines a cohort of patients who suffered bleeding requiring hemostatic intervention after oral surgery. The reasons for bleeding and the interval between surgery and onset of bleeding are investigated. MATERIALS AND METHODS: Between 1998 and 2009, 1,819 cases were eligible for this retrospective study. Factors (independent parameters) influencing the interval (dependent variable) were analyzed using negative binomial count regression models (NegBin II). The significance of each regressor's effect was tested using Wald's test and the total effect using likelihood ratio test. RESULTS: Of the patients examined, 1,101 (60.1 %) did not take anticoagulants, 394 (21.5 %) took phenprocoumon, 233 (12.7 %) took acetylsalicylic acid, 33 (1.8 %) took clopidogrel, 17 (0.9 %) took more than one anticoagulant, and 78 (4.3 %) had a congenital blood disorder. After simple tooth extraction, 95.3 % suffered bleeding; 69.7 % of extractions were performed in the molar region. Later that day of surgery, 66.0 % of all patients showed bleeding. The bleeding interval was significantly prolonged by anticoagulant therapy with phenprocoumon, by congenital clotting disorders. CONCLUSIONS: Normal tooth extractions are underestimated for their risk for postoperative bleeding, especially in the molar region. Anticoagulant therapy or congenital blood disorders present oral surgeons with a further challenge. CLINICAL RELEVANCE: Performing surgery before midday allows surgeons managing postoperative bleeding themselves for a better patient satisfaction. Intensified information about correct postoperative behavior is crucial. Prolonged blood coagulation should intensify follow-up checks. Patients with congenital blood disorders and patients at high risk for bleeding with the need for substitution of platelets or clotting factors should receive inpatient care. More potent, local applicable coagulant agents are required for these patients.

Comparison of cone-beam and conventional multislice computed tomography for image-guided dental implant planning.

OBJECTIVES: To compare the accuracy of cone-beam CT (CBCT) and multislice CT (MSCT) with regard to its use in image-guided dental implant surgery in a prospective model based study. MATERIAL AND METHODS: Ten photopolymer-acrylate mandibula models, each with four precise metal reference markers, were scanned with MSCT and CBCT. The six reference distances between the markers were measured by a three-axis milling machine first. The distances were then measured by (1) navigation with the Medtronic StealthStation® TREON™ image-guided surgery system, (2) with the Medtronic planning-tool and (3) on the PC with the Mimics® software. Mean values were calculated for all three methods for CBCT and MSCT and were compared for statistical significance. RESULTS: Of all measurements, 83% of the arithmetic mean values were within the ±0.5 mm range (MSCT 88% and CBCT 78%) and 17% within the ±1.0 mm range (MSCT 12% and CBCT 22%). The absolute difference of the arithmetic mean values showed no statistically significant difference between MSCT and CBCT. The difference of the overall mean values to the reference was 0.43 mm for MSCT and 0.46 mm for CBCT. CONCLUSIONS: The data of our study prove that the application of CBCT for the indicated purpose yielded good results comparable to those of MSCT. All three measuring methods were feasible and accuracy was statistically not different between the data acquired by MSCT and CBCT within the setting of this study.

Application of platelet-rich plasma for enhanced bone regeneration in grafted sinus.

PURPOSE: The present study was conducted to evaluate the effect of platelet-rich plasma (PRP) on new bone formation and remodeling after grafting of the maxillary sinus with an algae-derived hydroxyapatite AlgOss/C Graft/Algipore. MATERIALS AND METHODS: Fourteen consecutive patients with severely atrophic maxillae underwent uni- or bilateral grafting of the maxillary sinus with a mixture of collected bone, algae-derived hydroxyapatite AlgOss/C Graft/Algipore (ratio 1:10), and a combined addition of PRP and thrombin (Tissucol Kit; Baxter, Vienna, Austria) to allow for fast clotting. After an average healing period of 7.1 months bone samples were retrieved. Patients from a former consecutive series treated without PRP served as control group. Statistical analysis was done by Welch 2-sample t test and mixed linear model testing. RESULTS: In the coronal specimen portions, mean values for newly formed bone area, biomaterial area and marrow space of 32.2% ± 10.4%, 20.1% ± 13.0%, and 47.7% ± 8.5% were found with PRP, respectively. In the control group the corresponding values were 27.6% ± 13.4%, 20.3% ± 12.9%, and 52.1% ± 9.3%. In the apical specimen portions in the PRP group, the newly formed bone area, biomaterial area, and marrow space was 25.7% ± 15.0%, 23.4% ± 14.9%, and 50.9% ± 12.5%, respectively. The corresponding values in the control group were 17.0% ± 8.6%, 34.5% ± 11.2%, and 48.5% ± 8.5%. CONCLUSIONS: Statistical evaluation of the samples proved significantly better overall resorption of algae-derived hydroxyapatite AlgOss/C Graft/Algipore and increased new bone formation when PRP was used, especially in the apical region.