The problems caused by proximal contact loss (PCL) of dental implants have been a mainstream research topic in recent years, and scholars are unanimously committed to analyzing their causes and related factors, aiming to identify solutions to the problems related to PCL. The effects of the anterior component of force (ACF), the lifelong remolding of the adult craniofacial jaw and alveolar socket, and the osseointegration characteristics of dental implants are the main causes of PCL. On the one hand, the closing movement of the mandible causes the ACF of the tooth to move through the posterior molar cusp. Moreover, drifting between the upper and lower posterior teeth and mandibular anterior teeth can cause the anterior teeth of the upper and lower jaws to be displaced labially. On the other hand, reconstruction of the jaw, alveolar socket and tooth root, the forward horizontal force of the masticatory muscles, the dynamic component of the jaw and the forward force generated by the oblique plane of the tooth cusp can cause the natural tooth to experience near-middle drift. Additionally, natural teeth can shift horizontally and vertically and rotate to accommodate remodeling of the stomatognathic system and maintain oral function. Nevertheless, the lack of a natural periodontal membrane during implant osseointegration, the lack of a physiological basis for near-medium drift, the small average degree of vertical motion and the integrated silence of dental implants without the overall drift characteristics of natural teeth increases the probability of PCL. The high incidence of PCL is clearly associated with the duration of prosthesis delivery and the mesial position; but it is also affected by the magnitude of the bite force, occlusion, the adjacent teeth, restoration design, implant location, jaw, and patient age and sex. PCL has shown a significant correlation with food impaction, but not a one-to-one correspondence, and did not meet the necessary and sufficient conditions. PCL is also associated with peri-implant lesions as well as dental caries. PCL prevention included informed consent, regular examinations, selection of retention options, point of contact enhancement, occlusal splints, and the application of multipurpose digital crowns. Management of the PCL includes adjacent contact point additions, orthodontic traction, and occlusal adjustment. Existing methods can solve the problem of food impaction in the short term with comprehensive intervention to seek stable, long-term effects. Symmetric and balanced considerations will expand the treatment of issues caused by PCL.

Digital intraoral scanning is a hot topic in the field of oral digital technology. In recent years, digital intraoral scanning has gradually become the mainstream technology in orthodontics, prosthodontics, and implant dentistry. The precision of digital intraoral scanning and the accuracy and stitching of data collection are the keys to the success of the impression. However, the operators are less familiar with the intraoral scanning characteristics, imaging processing, operator scanning method, oral tissue specificity of the scanned object, and restoration design. Thus far, no unified standard and consensus on digital intraoral scanning technology has been achieved at home or abroad. To deal with the problems encountered in oral scanning and improve the quality of digital scanning, we collected common expert opinions and sought to expound the causes of scanning errors and countermeasures by summarizing the existing evidence. We also describe the scanning strategies under different oral impression requirements. The expert consensus is that due to various factors affecting the accuracy of digital intraoral scanning and the reproducibility of scanned images, adopting the correct scanning trajectory can shorten clinical operation time and improve scanning accuracy. The scanning trajectories mainly include the E-shaped, segmented, and S-shaped methods. When performing fixed denture restoration, it is recommended to first scan the abutment and adjacent teeth. When performing fixed denture restoration, it is recommended to scan the abutment and adjacent teeth first. Then the cavity in the abutment area is excavated. Lastly, the cavity gap was scanned after completing the abutment preparation. This method not only meets clinical needs but also achieves the most reliable accuracy. When performing full denture restoration in edentulous jaws, setting markers on the mucosal tissue at the bottom of the alveolar ridge, simultaneously capturing images of the vestibular area, using different types of scanning paths such as Z-shaped, S-shaped, buccal-palatal and palatal-buccal pathways, segmented scanning of dental arches, and other strategies can reduce scanning errors and improve image stitching and overlap. For implant restoration, when a single crown restoration is supported by implants and a small span upper structure restoration, it is recommended to first pre-scan the required dental arch. Then the cavity in the abutment area is excavated. Lastly, scanning the cavity gap after installing the implant scanning rod. When repairing a bone level implant crown, an improved indirect scanning method can be used. The scanning process includes three steps: First, the temporary restoration, adjacent teeth, and gingival tissue in the mouth are scanned; second, the entire dental arch is scanned after installing a standard scanning rod on the implant; and third, the temporary restoration outside the mouth is scanned to obtain the three-dimensional shape of the gingival contour of the implant neck, thereby increasing the stability of soft tissue scanning around the implant and improving scanning restoration. For dental implant fixed bridge repair with missing teeth, the mobility of the mucosa increases the difficulty of scanning, making it difficult for scanners to distinguish scanning rods of the same shape and size, which can easily cause image stacking errors. Higher accuracy of digital implant impressions can be achieved by changing the geometric shape of the scanning rods to change the optical curvature radius. The consensus confirms that as the range of scanned dental arches and the number of data concatenations increases, the scanning accuracy decreases accordingly, especially when performing full mouth implant restoration impressions. The difficulty of image stitching processing can easily be increased by the presence of unstable and uneven mucosal morphology inside the mouth and the lack of relatively obvious and fixed reference objects, which results in insufficient accuracy. When designing restorations of this type, it is advisable to carefully choose digital intraoral scanning methods to obtain model data. It is not recommended to use digital impressions when there are more than five missing teeth.

The standardized workflow of computer-aided static guided implant surgery includes preoperative examination, data acquisition, guide design, guide fabrication and surgery. Errors may occur at each step, leading to irreversible cumulative effects and thus impacting the accuracy of implant placement. However, clinicians tend to focus on factors causing errors in surgical operations, ignoring the possibility of irreversible errors in nonstandard guided surgery. Based on the clinical practice of domestic experts and research progress at home and abroad, this paper summarizes the sources of errors in guided implant surgery from the perspectives of preoperative inspection, data collection, guide designing and manufacturing and describes strategies to resolve errors so as to gain expert consensus. Consensus recommendation: 1. Preoperative considerations: the appropriate implant guide type should be selected according to the patient's oral condition before surgery, and a retaining screw-assisted support guide should be selected if necessary. 2. Data acquisition should be standardized as much as possible, including beam CT and extraoral scanning. CBCT performed with the patient’s head fixed and with a small field of view is recommended. For patients with metal prostheses inside the mouth, a registration marker guide should be used, and the ambient temperature and light of the external oral scanner should be reasonably controlled. 3. Optimization of computer-aided design: it is recommended to select a handle-guided planting system and a closed metal sleeve and to register images by overlapping markers. Properly designing the retaining screws, extending the support structure of the guide plate and increasing the length of the guide section are methods to feasibly reduce the incidence of surgical errors. 4. Improving computer-aided production: it is also crucial to set the best printing parameters according to different printing technologies and to choose the most appropriate postprocessing procedures.

After tooth extraction, significant absorption occurs in the soft and hard tissues of the alveolar ridge. The goal of alveolar ridge preservation is to maintain the volume and shape of the alveolar ridge's soft and hard tissues as much as possible so as to provide suitable conditions for implant placement. Currently, there are challenges in classifying the socket for alveolar ridge preservation, such as the difficulty in directly guiding the selection of graft materials and clinical procedures and the insufficient space for particle xenograft maintenance, resulting in poor bone regeneration. Plasmatrix is an autologous blood derivative that effectively enhances tissue regeneration. This article introduced the characteristics of soft and hard tissue defects after tooth extraction and the primary applications of plasmatrix for alveolar ridge preservation (liquid plasmatrix, solid plasmatrix membrane/plug, and plasmatrix bone blocks) as well as the proposed methods for the reclassification of sockets for alveolar ridge preservation based on soft and hard tissue defects at the extraction site to facilitate the creation of clinical recommendations. The proposed classifications are as follows: Class I, extraction socket without bone defect, with or without soft tissue defect; Class Ⅱ, extraction socket with bone defect, both sides with bone wall defect less than 50%, with or without soft tissue defect; Class Ⅲ, extraction socket with bone tissue defect, at least one side with bone wall defect greater than 50%, with or without soft tissue defect. For the Class I socket, a solid plasmatrix membrane or plug is inserted, followed by injection of liquid plasmatrix, using a double-layer solid plasmatrix membrane for socket closure; for the ClassⅡ socket, plasmatrix bone blocks are inserted, followed by injection of liquid plasmatrix and secondary solidification, using absorbable collagen membrane and double-layer solid plasmatrix membrane for socket closure; for the ClassⅢ socket, tenting screws are used to maintain height, followed by implantation of plasmatrix bone blocks, injection of liquid plasmatrix and secondary solidification, using absorbable collagen membrane and double-layer solid plasmatrix membrane for socket closure. The aim of this article is to provide comprehensive knowledge of plasmatrix for oral clinicians to serve as a reference to simplify the clinical decision-making process and procedures for alveolar ridge preservation.

After tooth extraction, labial contour collapses due to inevitable physiologic bone remodeling. To achieve optimal outcomes for pink esthetic treatment at anterior implant sites, bone or soft tissue augmentation has been advocated to maintain or reconstruct the labial tissue contour. When choosing soft tissue augmentation for esthetic restoration, it is necessary to strictly grasp the indications for surgery. Soft tissue augmentation to maintain or reconstruct the labial tissue contour could be considered in patients with healthy soft tissue and no bone defects or only mild horizontal bone defects. In immediate, early and late implant placement, the timing of soft tissue augmentation may vary. In immediate implantation, the labial bone plate is intact, so it is highly recommended to simultaneously manage soft tissue during implant placement. However, patients may have large bone defects with early or late implant placement. The risk of augmenting bone and soft tissue simultaneously is likely too high, and bone augmentation surgery is often performed at the first stage while soft tissue augmentation surgery is performed at the second stage. Therefore, soft tissue surgery is often carried out simultaneously with abutment connection. Currently, soft tissue augmentation is achieved mostly with adjacent autologous soft tissue grafts, such as free gingival grafts, subepithelial connective tissue grafts or pedicle palatal flaps, which are often accompanied by a second surgical area. The replacement of autogenous soft tissue grafting with new biological materials will become an inevitable trend. In this article, we analyze and summarize the indications, timing and different methods of soft tissue augmentation to maintain and reconstruct the labial contour.

At present, implant surgery robots have basically achieved "surgical intelligence", but "brain-inspired intelligence" of robots is still in the stage of theory and exploration. The formulation of a clinical implantation plan depends on the timing of implantation, implantation area, bone condition, surgical procedure, patient factors, etc., which need to evaluate the corresponding clinical decision indicators and clinical pathways. Inspired by evidence-based medicine and the potential of big data and deep learning, combined with the data characteristics of clinical decision indicators and clinical pathways that can be quantitatively or qualitatively analyzed, this review simulates the cognitive behavior and neural mechanisms of the human brain and proposes a feasible brain-inspired intelligence scheme by predicting the decision indices and executing clinical pathways intelligently, that is, "select clinical indicators and clarify clinical pathways -- construct database -- use deep learning to intelligently predict decision indicators -- intelligent execution of clinical pathways -- brain-inspired intelligence of implant decision-making". Combined with the previous research results of our team, this review also describes the process of realization of brain-inspired intelligence for immediate implant timing decisions, providing an example of the comprehensive realization of brain-inspired intelligence of implant surgery robots in the future. In the future, how to excavate and summarize other clinical decision factors and select the best way to realize the automatic prediction of evidence-based clinical indicators and pathways and finally realize the complete intellectualization of clinical diagnosis and treatment processes will be one of the directions that dental clinicians need to strive for.

Ideal sutures can provide great fixation, wound closure and a stable environment for healing of the surgical site. Tension-free apposition sutures are important for tissue regeneration and could tackle insufficient amounts of soft and hard tissue, especially in missing tooth sites that require implantation. The internal horizontal mattress suture, similar to the conventional horizontal mattress suture, forms a rectangle that can be bisected by the incision with both intrusion and extrusion of the needle on each side. On the basis of the rectangle, the internal horizontal mattress suture emphasizes that the suture should be located below the incision, so the eversion of the wound margin is the highlight of this procedure. The internal horizontal mattress suture could stabilize the graft on the targeting tissue, realize the fixation of the collagen membrane, apically repositioned flap and soft tissue graft, reduce the tension on the incision, and further release the tension of the incision margin. Beyond the primary need for fixation and wound closure, internal horizontal mattress sutures can also achieve stress interruption that reduces the interference of the surrounding muscle and can better master wound tension with the assistance of interrupted sutures. Given the above advantages, horizontal internal mattress sutures have great potential in the application of implant-related regenerative surgery. In this review, according to our experience in clinical practice and the literature, we summarize the advantages of internal horizontal mattress sutures in tissue augmentation. In addition, the sites and sequence to insert the needle and the spatial relationship between the suture and incision are clarified with the rationale of the naming pattern, which is conducive to experience exchange and clinical practice.

Vertical bone augmentation surgery still faces considerable challenges in clinical practice due to various problems, such as difficulty in restoring the ideal alveolar bone height and biological complications, and because it is highly technically sensitive. Plasmatrix is derived from patients’ own blood, and it can effectively promote the vascularization of the regenerated area, recruit stem cells, and reduce inflammation when used in vertical bone augmentation. Based on studies published worldwide, this article first divides vertical bone augmentation into 3 categories according to the height of the expected alveolar ridge, namely, type Ⅰ, the required vertical bone gain is less than 4 mm; type Ⅱ, the required vertical bone gain is between 4-8 mm; and type Ⅲ, the required vertical bone gain is greater than 8 mm. In the type Ⅰ vertical bone augmentation, the plasmatrix bone block is directly placed in the defect area and covered with the plasmatrix membrane before tension-free suturing; in the type Ⅱ vertical bone augmentation, the plasmatrix bone block should be placed in the defect area and fixed with titanium nails and then covered with an absorbable collagen membrane and plasmatrix membrane with a tension-free suture; in the type Ⅲ vertical bone augmentation, additional active ingredients (such as bone morphogenetic protein, autologous bone, etc.) should be added to the plasmatrix bone block and strong fixation (such as titanium nails) should be used. Absorbable collagen and plasmatrix membranes should be used to cover the surface of the bone block, and the flap should be sutured. According to different types of vertical bone augmentation categories, the above methods optimize the vertical bone augmentation effect. This article aims to provide a reference and guidelines for oral clinicians to fully understand plasmatrix and simplify the classification and operation of vertical bone augmentation.

Alveolar bone is an important anatomic basis for implant-supported denture restoration, and its different degrees of defects determine the choices of bone augmentation surgeries. Therefore, the reconstruction of alveolar bone defects is an important technology in the clinical practice of implant restoration. However, the final reconstructive effect of bone quality, bone quantity and bone morphology is affected by many factors. Clinicians need to master the standardized diagnosis and treatment principles and methods to improve the treatment effect and achieve the goal of both aesthetic and functional reconstruction of both jaws. Based on the current clinical experience of domestic experts and the relevant academic guidelines of foreign counterparts, this expert consensus systematically and comprehensively summarized the augmentation strategies of alveolar bone defects from two aspects: the classification of alveolar bone defects and the appropriate selection of bone augmentation surgeries. The following consensus are reached: alveolar bone defects can be divided into five types (Ⅰ-0, Ⅰ-Ⅰ, Ⅱ-0, Ⅱ-Ⅰ and Ⅱ-Ⅱ) according to the relationship between alveolar bone defects and the expected position of dental implants. A typeⅠ-0 bone defect is a bone defect on one side of the alveolar bone that does not exceed 50% of the expected implant length, and there is no obvious defect on the other side; guided bone regeneration with simultaneous implant implantation is preferred. Type Ⅰ-Ⅰ bone defects refer to bone defects on both sides of alveolar bone those do not exceed 50% of the expected implant length; the first choice is autologous bone block onlay grafting for bone increments with staged implant placement or transcrestal sinus floor elevation with simultaneous implant implantation. Type Ⅱ-0 bone defects show that the bone defect on one side of alveolar bone exceeds 50% of the expected implant length, and there’s no obvious defect on the other side; autologous bone block onlay grafting (thickness ≤ 4 mm) or alveolar ridge splitting (thickness > 4 mm) is preferred for bone augmentation with staged implant placement. Type Ⅱ-Ⅰ bone defects indicate that the bone plate defect on one side exceeds 50% of the expected implant length and the bone defect on the other side does not exceed 50% of the expected implant length; autologous bone block onlay grafting or tenting techniques is preferred for bone increments with staged implant implantation. Type Ⅱ-Ⅱ bone defects are bone plates on both sides of alveolar bone those exceed 50% of the expected implant length; guided bone regeneration with rigid mesh or maxillary sinus floor elevation or cortical autologous bone tenting is preferred for bone increments with staged implant implantation. This consensus will provide clinical physicians with appropriate augmentation strategies for alveolar bone defects.

Tooth loss is accompanied by alveolar bone absorption or defect, resulting in insufficient bone and soft tissue. In addition to restoring the masticatory function of missing teeth, implant treatment should also needs to restore the contour and shape of the dental arch. Guided bone regeneration is a common means of bone increase. Xenogeneic granular bone substitute materials are widely used in the field of clinical bone augmentation due to their advantages of long degradation time and low immunogenicity, but other problems, such as inconvenient operation and low osteogenic activity, remain. Plasmatrix can effectively improve the effect of oral tissue regeneration and reduce the occurrence of postoperative complications, and its application in oral tissue regeneration is gradually increasing. This article first introduces the main application forms of plasmatrix in horizontal bone augmentation (mainly solid plasmatrix membrane and plasmatrix bone block), and reclassifies horizontal bone defects according to commonly used decision-making schemes in clinical bone augmentation, in other words, whether the implant can be placed in the ideal position and whether there is bone dehiscence after implantation. Type Ⅰ defects refers to the situation where the bone at the implant site can allow the insertion of an implant with ideal size, and there is no bone dehiscence around the implant, but the alveolar bone contour is not ideal; type Ⅱ defects refers to the situation that when an ideal size implant is placed at the implant site determined by the future prosthesis position, there will be bones on three sides of the implant, but there is bone dehiscence in the buccal bone wall (the length of bone dehiscence is less than 50% of the implant length); type Ⅲ defects refers to the situation where the bone volume at the implant site is not enough to for the placement of the ideal size implant at the ideal position, and bone grafting is required to restore the bone volume before the implant placement. The application of plasmatrix in different types of bone defects is then described. In type Ⅰ bone defects, the solid plasmatrix membrane is used instead of the collagen membrane; in type Ⅱ bone defects, the bone defect around the implant is filled by plasmatrix bone block and then covered with collagen membrane and solid plasmatrix membrane; and in type Ⅲ bone defects, plasmatrix bone block is used to replace autogenous bone block to fill the defect area, and titanium screws are used for fixation. The defect is then covered with a collagen membrane and a solid plasmatrix membrane. This article aims to provide oral clinicians with a comprehensive understanding of plasmatrix and simplify the guidelines for bone regeneration operations.

Guided bone regeneration technology applied in alveolar bone defect regeneration is based on the barrier function and space maintenance of the barrier membrane. Therefore, traditional development strategies for barrier membranes focus on their physical barrier function, degradation characteristics and biocompatibility to avoid immunogenicity. However, not only does the barrier membrane passively block connective tissue, it is recognized as a “foreign body”that triggers a persistent host immune response, known as a foreign body reaction. The theories of osteoimmunology reveal a close relationship between the immune system and bone system and emphasize the role of immune cells in bone tissue-related pathophysiological processes. Based on these findings, we propose a novel development strategy for barrier membranes based on immune microenvironment regulation: by manipulating mechanical properties, surface properties and physiochemical properties, barrier membranes are endowed with an improved immunomodulation ability, which helps to regulate immune cell reactions to induce a favorable local immune microenvironment, thus coordinating osteogenesis and osteoclastogenesis as well as barrier membrane degradation to increase the efficiency of barrier membranes in GBR applications. In this paper, we review the development of barrier membranes and their close relationship to the immune microenvironment concerning bone regeneration and membrane degradation. Additionally, the outcomes of research on barrier membranes based on the regulation of the immune microenvironment have been summarized to improve the osteogenesis efficiency of barrier membranes and solve the problem of the regeneration and repair of bone defects, especially alveolar bone defects.

Chronic kidney disease is a global public health problem threatening human health and affects the function of multiple organ systems. The oral health of patients is often affected as the disease progresses. Dental implants have become the best way to repair tooth loss. It is necessary and challenging to provide safe and reliable dental implant treatment for patients with chronic kidney disease. Dental clinicians should evaluate the health of patients comprehensively, complete blood biochemistry, coagulation function, and imaging examinations, and provide feasible, reliable and personalized treatment plans. During the treatment phase, dental clinicians need to consider prophylactic antibiotics, painless minimally invasive surgery, infection control, and delayed restoration, and they must cooperate with other clinicians in multiple disciplines to reduce risks to provide personalized, safe, and effective oral implant treatment for patients with chronic kidney disease.

The nature, significance, parameters, influencing factors and testing of implant primary stability were studied by a literature review. Primary stability is a kind of anchorage force at the interface between the implant and bone, and it is merely mechanical. The significance of primary stability is to keep the implant unmovable so that the new bone can grow undisturbed on the surface of the implant without interference from fibrous tissue. The implant is finally bound to the bone by osseointegration. The most common assessments of primary stability are insertion torque (IT), the implant stability quotient (ISQ) of the resonance frequency analysis (RFA) and Periotest. IT is more commonly used to directly imply initial stability. At present, no consensus has been reached regarding the concrete parameters of primary stability to predict osseointegration. Implant osseointegration could be developed through all phases of primary stability. However, the excessive primary stability would cause mini-bone fractures, followed by bone necrosis at the interface and the final failure of implantation. Primary stability is influenced by three factors: implant design, bone condition of alveolar bone, and surgical technique. Under the condition of a lack of primary stability and immediate implantation, there may be the possibility of successful osseointegration. Therefore, it is necessary to re-examine the accuracy of the current elaboration on the primary stability. It is related directly to whether the clinic can choose the appropriate implant treatment path.

Rehabilitation and reconstruction of atrophic edentulous predicament represents significant challenges for implant dentists due to the anatomical conditions of the edentulous jaw. Implant-supported fixed complete dental prostheses represent a scientifically and clinically validated treatment for recovering patients, masticatory function and esthetic effect. However, the highly demanding implant surgical techniques and complex rehabilitation procedures for immediate functional reconstruction make it difficult to achieve the desired treatment outcomes. The application of digital and CAD/CAM technology in various stages of the treatment process is logical for patients and dentists. This article summarizes the workflow of digital-assisted implantation with immediate functional reconstruction of atrophic edentulous combined with a clinical case. Digital-assisted diagnosis, design, implantation, immediate reconstruction and final rehabilitation can optimize the implant surgery and immediate rehabilitation workflow, improve the accuracy of implant-supported immediate functional reconstruction, reduce the demand for a large amount of bone graft, and achieve higher patient satisfaction. The “prosthetic-oriented, begin with the end in mind” concept of edentulous jaw implant prosthetics can accurately and efficiently restore the patient,s beauty and chewing function in a minimally invasive manner, and is worthy of clinical promotion.

The crown-root ratio (C/R) theory of natural teeth has been widely recognized in the field of stomatology,and has important clinical significance in predicting and assessing the prognosis?of natural teeth as well as for abutment selection during denture restoration. In the past few decades, scholars have advocated for the implantation of implants as long in length as possible to improve the success rate according to the theory of crown-root ratio of natural teeth. However, with the application of short implants, our philosophy of implantation has changed, and the relationship between the crown-implant (C/I) ratio and complications has become one of the current research hotspots. In this paper, the concept of the crown-implant ratio, the research progress of the C/I ratio, the implant survival rate and clinical complications of implant?restoration were reviewed and summarized, and the following suggestions were put forward: although most studies have shown no significant correlation between the C/I ratio and implant survival or marginal bone loss, this relationship may increase the risk of mechanical complications. A C/I < 3 and a crown length < 15 mm are recommended in implant restoration; when ultra-short implants are applied, the implant system can increase the bone-to-implant contact area, and splint prostheses such as crown or bridge are recommended.

Maxillary sinus membrane lesions have been broadly detected before implant surgery in the posterior maxilla region, resulting in uncertainty regarding maxillary sinus floor elevation surgery. In this context, we composed this commentary article based on the current literature and the clinical experience of our department. We discuss the common lesion types shown by CBCT including membrane pathological thickening, polyps/cystic lesions and air-liquid level in the sinus. Maxillary sinus floor elevation surgery can be conducted in patients with membrane thickening of 2-5 mm or with polyps/cysts of less than half of the sinus height (because the above symptoms have little influence on the outcome of surgery). Membrane thickening of more than 5 mm with ostium obstruction, antrochoanalpolyps, mucoceles and cysts of more than half of the sinus height should be carefully treated. Different treatments can be performed such as conducting elevation surgery while retaining the cyst, removing the cyst before surgery or removing the cyst during surgery based on the cyst type and size, inflammation, patency of the ostium, etc. Antibiotics-anti-inflammatory-aspiration, surgical debridement and oral lesions eliminations are generally used for treating post-operative sinusitis. Presurgical radiographic evaluation is the key to diagnosing and treating these membrane lesions. We highly advocate collaboration between our dentists and otolaryngologists on this issue.

With the continuous development of maxillary sinus floor elevation technology, the osteogenesis mechanism of maxillary sinus floor elevation has always been a concern of scholars. The membrane of the maxillary sinus is an indispensable physiological structure in the process of space osteogenesis under the sinus floor after elevation of the sinus floor. In recent years, the role of the maxillary sinus floor mucosa in sinus floor space osteogenesis has been a research hotspot. Recent studies have found that the maxillary sinus floor membrane plays a role as a natural biological barrier membrane in the process of sinus floor space osteogenesis after maxillary sinus floor elevation; in addition, it has the ability to undergo osteogenesis. It has also been found that maxillary sinus membrane stem cells (MSMSCs) derived from the maxillary sinus floor membrane have characteristics of mesenchymal stem cells, which can differentiate into osteoblasts and participate in sinus floor space osteogenesis after maxillary sinus floor elevation. New studies have also found that small RNAs such as microRNAs, long noncoding RNAs and circular RNAs can regulate the osteogenic differentiation of MSMSCs, which may be important biological targets for promoting osteogenesis in the sinus floor space. In this paper, the relationship between the maxillary sinus floor mucosa and bone formation after maxillary sinus floor elevation, the barrier and osteogenic function of the maxillary sinus floor mucosa, the sources of osteoblasts involved in osteogenesis of the sinus floor space, and the molecular regulatory mechanisms of stem cells derived from maxillary sinus mucosa will be elucidated step by step.

Currently, computer-aided implant surgeries include implant placement surgery under the guidance of a dynamic navigation system. With the use of software inherent in the navigation system, doctors can make a preoperative plan including the ideal position of the implant. Then the plan can be accurately transferred to the surgery, during which the real-time condition of the drill and its relationship with the surgical region will be visualized by the surgeon and the drill can be adjusted in a timely manner. Currently the dynamic navigation system is increasingly widely utilized, especially in cases of esthetic zones or surgical sites with important anatomical structures. However, the clinical workflow of the navigation system is complicated, including CBCT taken after the registration device placement, prosthetic-driven 3D design, calibration, registration, navigated borehole preparation and implant placement surgery. Many details should be considered when the device is applied, including implant position design, fixation of the tracking device, registration, and stable borehole preparation under the guidance of dynamic navigation. Therefore, this article introduces the dynamic navigation system into the clinical workflow and evaluates, the effects of the application and the clinical features. The new progress of the navigation system in the field of implantology is demonstrated at the same time, including navigated surgery in fully edentulous arches and in the zygomatic zone. Further improvements in the navigation system in terms of the accuracy and simplification of the workflow are needed in the future.

Microbial infections affect people worldwide. Quaternary ammonium salts serve antibacterial, antifungal, antiviral, anti-matrix metalloproteinase and polymerization functions. While the modification of biomaterials with quaternary ammonium salts cannot affect the physical or chemical properties of the biomaterials, this process can confer them with stable biological activity. Currently, quaternary ammonium salts are widely used in the development of functional orthopedic materials, sutures, dressings and dental materials, and the idea of modifying biomedical materials with quaternary ammonium salts has become the most promising, e.g., for preparing antimicrobial biomaterials. Recent studies have found that quaternary ammonium salt-modified antimicrobial monomers are cytotoxic. Therefore, it is of great significance to explore the cytotoxic mechanism of quaternary ammonium salt-modified antimicrobial monomers and determine possible cytoprotective measures for improving the biological safety of these antimicrobial resin-based materials and expanding their clinical applications. In addition, further validation of the clinical efficacy of these biomaterials is particularly important for accurately evaluating the clinical prospects of these biomaterials. Based on a literature review, this paper summarizes the applications and toxicity of biomedical materials modified with quaternary ammonium salts.

In 2017, there were 451 million people (ages 18 to 99) with diabetes worldwide, and this number is expected to grow to 592 million by 2035. A series of complications in diabetic patients often leads to oral vascular and bone lesions. Therefore, dental implant doctors urgently need to understand the clinical characteristics of diabetes mellitus patients to provide the best treatment. For dental implant doctors, the following problems still exist in the treatment of diabetic patients with poor blood sugar control: ① alveolar fossa healing in diabetic patients is slow after extraction, and bone regeneration is often needed, which prolongs the treatment cycle and increases the pain of patients; ② the rate of new bone formation in diabetic patients after alveolar bone grafting is slow; ③ it takes a long time for the body to achieve effective bone bonding after dental implantation in diabetic patients, and the outcomes are poor; ④ the health of the tissue around dental implants is affected by blood sugar level, which is difficult to maintain in diabetic patients. Current studies suggest that the long-term success rate of implants is predictable in diabetic patients when blood sugar levels are well controlled (HbA1c < 6%). This article will review the current research status of dental implantation therapy for diabetic patients to provide a reference for clinical practice.

The traditional biological principle for developing bone biomaterials is to directly stimulate the osteogenic differentiation of osteoblastic lineage cells, the direct effector cells for osteogenesis. This strategy has been successful for the development of bone biomaterials. However, recent progress in bone biology has revealed the vital role of the local bone microenvironment, especially the immune environment, in controlling osteogenesis. Interdisciplinary osteoimmunology has found that the osteoimmune and skeletal systems are closely related, sharing numerous cytokines and regulators. In addition, immune cells play an important role in the physiological and pathological processes of the skeletal system, suggesting that neglecting the importance of the immune response is a major shortcoming of the traditional strategy. Based on this principle, we propose a novel “osteoimmunomodulation”-based strategy to meet the strict requirements of new-generation bone biomaterials: instead of directly regulating the osteogenic differentiation of osteoblastic lineage cells, we should focus more on manipulating the responses of immune cells and developing biomaterials to induce an immune environment that provides conditions that balance osteogenesis and osteoclastogenesis for optimal osseointegration. This article reviews the recent progress on osteoimmunology and immunomodulatory biomaterials for the generation of the “osteoimmunomodulation” concept. Additionally, the outcomes of “osteoimmunomodulation”-related studies have been summarized to guide the development of advanced “osteoimmune-smart” bone substitute materials.

With the development of implant dentistry and biomaterials, dental implants have become the first rehabilitative option proposed for the treatment of missing teeth. Most studies about dental implants and biomaterials currently focus on osteogenesis and the osseointegration of the implant, neglecting the importance of the immune response. In recent years, the development of osteoimmunology has been one of the greatest achievements in bone biomaterials; osteoimmunology has revealed the vital role of immune cells in regulating bone dynamics, implying the value of studies on materials with favorable osteoimmunomodulatory properties. This article reviews the integration between bone tissue and implants and summarizes the effects of the immune response during osseointegration and new bone formation to show the importance of regulating the immune response in this process. The effect of macrophages on osteogenesis and osteoclastogenesis is then reviewed due to the high plasticity and multiple roles of macrophages during this process. Accordingly, the interaction between the implants, the immune systems and the skeletal system is explained, showing the potential value of osteoimmunomodulation as a biological principle for developing bone biomaterials and new types of implants.

Transcrestal sinus floor augmentation applied for severely atrophic maxilla sinus floor augmentation is frequently performed because of posterior maxilla resorption and low bone density. The traditional perspective is that the residual bone height is a main factor influencing the selection of the augmentation technique and the transcrestal technique can only be used when the residual bone height is more than 4-5 mm. However, many researchers have used this technique with lower bone heights because of the development of better surgical instruments and clinical skills. Based on the review of the literature in recent years and the author′s understanding of clinical operation, this paper reviews the improvement progress and operation skills of the application of transalveolar ridge top maxillary sinus lift in the severely absorbed maxillary posterior tooth area.

With the development of digitalization, information and internet technology, digital dental aesthetic restoration technology is changing the traditional mode of treatment. The development of digital aesthetic restoration therapy is similar to the digital development track in other fields of medicine, in which the use of digital technology for intervention in particular treatment steps is evolving to digitalization throughout the treatment process. Digitalization improves the precision and quality of aesthetic restoration, increases the efficiency of clinical work and is favorable for patients. Digitalization could replace traditional methods, propelling aesthetic restoration into a fully digitalized era. Function, aesthetics and minimal invasiveness are the three major concepts of contemporary prosthodontics, and digital aesthetic restoration technology represents a perfect interpretation of these three concepts. This paper describes recently developed digital technologies for aesthetic restoration and cites the advantages, limitations, and developmental direction of digital restoration dentistry.

Technical complications associated with implant prostheses include abutment or screw loosening, abutment or screw fractures, implant fractures, fracture of the veneering material and loss or misfitting of retention equipment. In this review, implant prostheses are classified as implant-supported single crowns (SCs), implant-supported fixed dental prostheses (FDPs) or implant-supported fixed complete dentures (FCDs). We evaluated the incidence of technical complications based on the clinical literature published after 2000. Then, we analyzed the reason, prevention and clinical management of abutment or screw loosening, abutment or screw fractures, implant fractures, fracture of the veneering material and loss or misfitting of retention, to reduce the incidence of complications and provide guidance for future oral implant treatment.

Bone is a hierarchically structured and highly mineralized hard tissue composed of an organic phase (type I collagen and noncollagenous proteins) and an inorganic phase (nanohydroxyapatite). Intrafibrillar mineralized collagen is the basic structural unit of bone tissue and is of high significance due to its superior mechanical and biological properties. Thus, to truly understand the unique properties of bone, it is necessary to review the most basic structural level of bone. In this article, we review the recent advances in understanding the development of intrafibrillar mineralization and the prevailing theories in the formation of such intrafibrillar minerals. Understanding the mechanisms of intrafibrillar mineralization may facilitate the development of engineered bone for clinical applications and provide deeper insight into the nature of biomineralization.

Dynamic surgical navigation system has been wildly used in implantology, the navigation surgical system provide preoperative trajectory planning. Moreover, the constant visualization of drilling trajectory during operation assist the operators by avoiding critical anatomic structures to achieve safer surgery. Our article focuses on the development and function of dynamic navigation system to evaluate the accuracy of dynamic surgical navigation system when used for regular implants and zygomatic implants placement. We aim to discuss the accuracy of different brand of dynamic surgical navigation systems for implants placement and to investigate the main reasons led the inaccurate outcome.

In recent years, the number of edentulous patients has been increasing with the increase of aging popula-tion and the number of patients with complete denture. Denture adhesive is an indispensable material of denture reten-tion intensifier in the clinic, which has been used for long periods in patients with full denture or partial denture. In this paper, we made a brief introduction according to the denture adhensive classification, mechanism of action, clinical at-tention and the latest research progress.

To seek convenient and effective method for reconstruction of edentulous jaw, Maló and his colleagues developed All-on-Four implant immediate-function concept. The principle of All-on-Four is to support the full-arch prosthesis by 4 implants and to achieve immediate loading after surgery. Its advantages include avoiding additional bone grafting, evading critical anatomical structures and immediate prosthesis. In recent years, All-on-Four technique has been widely utilized in clinical practice as a viable approach for edentulous patients. With the auxiliary of guided surgery and biomechanical researches, All-on-Four has achieved predictable clinical results. In this paper, the development, investigation of biomechanics and main points of surgery and prosthesis of All-on-Four were briefly reviewed.

Maxillary sinus floor elevation is a common method to increase the bone height in posterior maxilla. Maxillary sinus floor elevation can be divided into 2 types: sinus floor elevation with lateral window approach and sinus floor elevation with trans-alveolar approach. The present article reported the anatomy, antibiotics choice, indications, grafting, growth factors, complications and the influence of tobacco on maxillary sinus floor elevation.

Dental implant restoration is an effective way to restore the chewing and aesthetic function for edentulous. However, dental implant restoration is facing great challenges of the lack of available bone, the maxillary sinus or inferior alveolar nerve vascular bundle, which is often necessary to carry out the related bone augmentation operation. All-on-Four technique is to use four implants in the anterior part of complete edentulous jaws, the two most anterior implants are placed axially whereas the two posterior implants are placed distally angled, to support a provisional, fixed, and immediately loaded prosthesis. The technique avoids the artificial bone substitutes implantation and maxillary sinus augmentation or other bone augmentation surgery. Besides, it could alleviate patients' psychological reaction, postoperative reaction, as well as time and money costs. It is considered a feasible treatment method to combine the application of the oblique implant and the axial implant in the treatment of the edentulous patients. This paper will elaborate on the concept of All-on-Four, the conventional technology, the evaluation research and some new viewpoints.

Nowadays, dental implant is the first therapeutic choice of the edentulous patients. A firm functional soft tissue seal between the transmucosal part of implants and the surrounding soft tissues is significant to the long-term survival of the implant as well as the stable osseointegration. There are many research on the osseointegration, but less in the transmucosal part of the implant. In this review, we combined the implant neck design of our own with the international study in this field, in order to discuss the relationship between the implant neck design and the marginal bone loss, interact with the soft tissue, the antibacterial activity.

Short implants can be used as an alternative in cases of insufficient vertical bone volume after dentition defect or absence of dentition to simplify or avoid bone augmentation procedures. Short implants (≤ 6 mm) are reported to have a mean survival rate of 96% after a period of 1-5 years in function and have been widely used in cases of dentition defects or absence of dentition. Compared with conventional implants (≥ 10 mm) combined with bone augmentation procedures, short implants have fewer surgery-related complications, less marginal bone loss, shortened treatment times and reduced costs, and are preferred by patients. Due to a lack of evidence, a high crown-implant ratio should not be an obstacle for the use of short implants. In addition, most of the current literature has not enough follow-up time, the long-term implant survival data of short implants remain unclear. To improve the clinical outcomes of short implants, attention should be paid to the implant site, bone quality, and occlusal force as well as to the presence of oral health maintenance, periodontal diseases and habits through a careful intraoral and radiographic examination. The choices of wider implant use and splint restoration are recommended, occlusal force should be paid attention during implant maintenance. Inappropriate stress on restorations should be avoided. Future studies should be focused on the long-term clinical outcomes of short implants.