Biomechanics of the knee

In this article the biomechanics of the tibiofemoral joint, patellofemoral joint and menisci are discussed. Normal knee kinematics depend on soft tissue and bony structures working closely together. Implant manufacturers have considered this interaction in order to design and develop a broad spectrum of total knee replacement (TKR) implant solutions. These designs include anatomic and functional considerations, asymmetric or symmetric implants, mobile or fixed bearing offerings and ‘high flexion’ designs, as well as designs with a single or multiple radii of curvature. Substantial differences in outcome between these designs remains unproven and TKR design selection at present is therefore often based on other factors, such as cost and the surgeon's familiarity with a particular knee system. An understanding of knee biomechanics pertaining to implant design will help surgeons with implant selection and help refine the method of implantation to optimize patient outcomes.     

(i) Planning and consent for primary total knee replacement

The aim of primary total knee replacement is to decrease pain, restore function and reduce disability. This is achieved by correct patient selection and adequate planning so that the appropriate prosthesis can be implanted in the appropriate manner. The technical goal of total knee arthroplasty is to implant a well-aligned prosthesis in a well-balanced knee, with linear patellar tracking and achieve infection-free healing.Weight bearing anteroposterior, lateral and patellofemoral joint radiographs are mandatory and standing long leg views help determine alignment. CT and MRI scans may be of value in assessing bone stock and ligamentous deficiency. If there is a lack of bone stock a stemmed prosthesis or augmentation wedges may be required, whilst a ligamentous deficiency may necessitate a stabilized or constrained prosthesis.The consent process for TKR commences at the outpatient consultation and must consider the reason for operation, alternative treatments, all common and serious risks and the rehabilitation protocol. There is an increasing use of multimedia tools (e.g. www.orthoconsent.com) in the consent process.     

Dual-purpose, radiographic-surgical implant template: fabrication technique

A technique for fabrication of an implant radiographic-surgical template for the partially-edentulous patient is proposed. A mixture of barium sulfate and acrylic resin provides a radiopaque template of the planned implant restorations in relation to the hard tissues. This template is easily converted to a surgical guide.     

罹患牙周牙髓联合病变下颌磨牙拔除后运用牙槽嵴保存术提高种植治疗安全性的效果观察（附1例3年随访报告）

种植治疗作为修复牙列缺损的重要方式,充足的软硬组织条件是种植修复成功的必要条件。下颌磨牙区与下颌管关系紧密,种植治疗时种植体最根方与下颌管间应保持一定的安全距离,避免神经损伤。罹患重度牙周病变的下颌磨牙自然愈合后常常骨量不足,要实现以修复为导向的种植治疗的难度与风险大大增加。牙槽嵴保存术能够阻止或减缓牙槽骨宽度及高度的丧失,为种植治疗创造良好的骨量条件。文章展示了1例因牙周牙髓联合病变保留无望的下颌第二磨牙行微创拔牙同期牙槽嵴保存术后6个月实施种植修复治疗的过程,提高了种植治疗的安全性并取得了良好的治疗效果,积累了针对此类病例的临床经验。     

A review of the functional and esthetic requirements for dental implants

BACKGROUND: The esthetic replacement of teeth has become an important standard for implant dentistry. While defining this goal has not been difficult, the ability to restore implants esthetically has been fraught with obstacles and sometimes has not been attainable. The purpose of this review is to summarize essential anatomical and surgical considerations for cosmetic implant dentistry. METHODS: This article provides a summary of the predominant findings from clinical studies and case reports that help develop implant surgical guidelines for better esthetic outcomes. RESULTS: Soft- and hard-tissue requirements for placing an implant in an ideal position are defined. The authors discuss the best treatment approaches as well as the limitations associated with esthetic implant placement. They evaluate the available data specifically for the maxillary anterior sextant, since this anatomical region has higher esthetic demands. CONCLUSIONS: Several parameters and various surgical techniques have been developed to manipulate soft- and hard-tissue contours and to control the esthetic outcome for implant-supported restorations. CLINICAL IMPLICATIONS: It is essential for practitioners to understand the anatomical basis for and limitations of implant dentistry in the esthetic zone.     

Assessing the space limitation inside a complete denture for implant attachments

Accurate determination of the space defined by the physiological contouring of a complete denture (before and after implant surgery) is required during the treatment-planning phase for an implant overdenture. This determination assists in formulating the proper surgical treatment plan and in selecting the appropriate independent implant overdenture attachment. This article presents a technique that provides clear, visual space limitation analysis of the removable prosthesis. The described method allows the clinician to determine the available space before the implant or attachment is placed.     

Fabricating an Accurate Implant Master Cast: A Technique Report

The technique for fabricating an accurate implant master cast following the 12‐week healing period after Teeth in a Day® dental implant surgery is detailed. The clinical, functional, and esthetic details captured during the final master impression are vital to creating an accurate master cast. This technique uses the properties of the all‐acrylic resin interim prosthesis to capture these details. This impression captures the relationship between the remodeled soft tissue and the interim prosthesis. This provides the laboratory technician with an accurate orientation of the implant replicas in the master cast with which a passive fitting restoration can be fabricated.     

Preserving the socket dimensions with bone grafting in single sites: an esthetic surgical approach when planning delayed implant placement

Recent advancements in barrier membranes, bone grafting substitutes, and surgical techniques have led to a predictable arsenal of treatment methods for clinicians who practice implant dentistry. The contemporary clinician is supplied with proven knowledge, substantiated materials, and instrument inventory that allows implant placement in cases that used to be reserved for the specialist in the past because of their complexity. Nowadays, postextraction alveolar ridge maintenance can be a predictable procedure and can certainly aid the clinician in preventing ridge collapse, thereby allowing for implant placement in a position that satisfies esthetics and function. Extraction socket maintenance for future implant therapy does not rule out immediate implant placement but rather provides an additional option when treatment planning implant patients. This article will focus on the concept of extraction socket preservation using regenerative materials. It will describe a technique suggested by the authors to resist bone resorption and soft tissue shrinkage following tooth extraction.     

Bone graft sandwich osteotomy to correct a malpositioned dental implant

As a result of inadequate planning, poor judgment, or losing one's orientation during surgery, implants may be placed in positions or at angulations that are less than ideal. The purpose of this report is to describe an alternative technique for the correction of a malpositioned osseointegrated implant by means of a maxillary anterior single implant segmental osteotomy associated with a ‘sandwich’ bone graft technique. The technique described provides an alternative option for the surgeon faced with a malpositioned endosseous implant. It allows for a predictable result with preservation of the cervical gingival architecture, creates a more ideal environment for dental restoration, reduces treatment time compared to other techniques, and does so in a cost-effective manner.     

Pouch roll technique for implant soft tissue augmentation: a variation of the modified roll technique

This paper presents three cases of peri-implant mucosal defects that were successfully treated with a newly proposed "pouch roll" implant soft tissue augmentation technique. This procedure uses a de-epithelialized connective tissue layer during the first or second stage of implant surgery over the underlying dental implant without the need for sutures. At 2 weeks, healing was remarkable, with excellent plaque control. At 3 months, only minimal tissue shrinkage was evident. As a result, a 2- to 3-mm increase in the width of the keratinized tissue was noted around the augmented implant site. This technique is an atraumatic, versatile, and cost-effective surgical modality that enhances the peri-implant soft tissue over the ridge with a soft tissue thickness ≥ 3 mm. The pouch roll implant soft tissue augmentation procedure provides an easy and less traumatic correction of a mild to moderate buccal ridge deficiency by thickening the soft tissue around the dental implant.     

Retrofitting a cast dowel-core on salvaged dental implants.

Dental implant screw fracture involves attempting to retrieve the screw fragment or, as an alternative, attempting to salvage the dental implant. Circumstances that do not allow for screw retrieval require a solution in which the internal configuration of the dental implant can provide for a custom direct dowel fabrication. The proposed technique is to retrofit the fabrication of a custom cast dowel-core and provisional use of a direct procedure, which provides accuracy of fit, retention, and ease of production.     

Success or failure of dental implants? A literature review with treatment considerations

This study reviews the literature concerning the success or failure of dental implants and provides the general dentist with information to decide whether to recommend dental implant therapy to a patient. The authors conducted an extensive literature search for articles relating to dental implant failure. Metaanalyses and multi-center studies were predominant in the selection. Predictors of dental implant success or failure were gleaned from various articles and presented in the form of text and tables. The main predictors for implant success are the quantity and quality of bone, the patient's age, the dentist's experience, location of implant placement, length of the implant, axial loading, and oral hygiene maintenance. Primary predictors of implant failure are poor bone quality, chronic periodontitis, systemic diseases, smoking, unresolved caries or infection, advanced age, implant location, short implants, acentric loading, an inadequate number of implants, parafunctional habits and absence/loss of implant integration with hard and soft tissues. Inappropriate prosthesis design also may contribute to implant failure.     

Traumatic problems of the patella

This article will outline the clinical presentation and management of patellar instability and fracture. Patellar instability is a generic term that describes anything from symptomatic apprehension to patellar subluxation and through to patellar dislocation. It can result from osseous abnormalities such as patella alta or patellofemoral dysplasia or it can arise secondary to soft tissue abnormalities such as a torn medial patellofemoral ligament. Failing conservative management, surgical treatment is directed to the underlying cause(s) of the instability, and can include medial patellofemoral ligament reconstruction or a bony realignment procedure.Patellar fracture is a common injury caused by excessive tension through the extensor mechanism or a direct blow. Such injury can lead to stiffness, extension weakness and patellofemoral arthritis. Non-surgical management is indicated for non-displaced fractures with an intact extensor mechanism. Surgical fixation is recommended for fractures that either disrupt the extensor mechanism or that demonstrate over 2–3 mm of step-off and/or over 1–4 mm of displacement. Anatomic reduction and fixation with a tension-band technique is associated with the best outcomes; however, symptomatic hardware is a frequent complication.     

种植修复中的牙合学问题

口腔种植修复技术的出现,为口腔修复提供了新的临床途径。种植修复中的咬合问题不仅对恢复美观及功能有着重要影响,还关乎种植的成败。在种植修复前需考虑天然牙与种植体存在的差异,并根据缺失牙范围、设定的修复体类型等对种植修复进行有针对性的咬合设计。本文旨在对种植义齿修复相关牙合学问题进行探讨。     

CAD/CAM全程手术导板结合改良根盾技术在前牙区即刻种植中的应用

目的 探讨CAD/CAM全程手术导板结合改良根盾技术在美学区即刻种植的临床效果,以期为CAD/CAM全程手术导板和改良根盾技术在临床应用提供借鉴.方法 对1例左侧上前牙外伤的病例进行即刻种植,应用改良根盾技术保存唇侧牙片,CAD/CAM全程手术导板引导种植体植入.结果 通过CAD/CAM全程手术导板引导即刻种植体植入和...     

Histologic evaluation of a 9-year-old hydroxyapatite-coated cylindric implant placed in conjunction with a subantral augmentation procedure: a case report.

The histologic examination of dental implants retrieved from humans provides a unique opportunity to evaluate the bone-implant interface. This case report presents a clinical, radiographic, and histologic evaluation of a cylindrical hydroxyapatite- (HA) coated implant retrieved from the posterior maxillary area of a patient after 9 years after placement. The implant had been placed in conjunction with a subantral augmentation procedure with HA as the graft material. Clinical examination revealed an immobile implant with no sign of pathosis. Radiographic examination indicated close proximity of the bone to the implant surface without evidence of radiolucency. Histologically, because of tissue destruction during implant retrieval, only the apical portion of the implant was available for examination under light microscopy, and it appeared to be integrated with the surrounding bone; 45.9% of the surface of the implant had close bone apposition at the interface. There was no evidence of dissolution of the HA coating and the bone appeared to be in immediate contact with the coating. Residual graft particles were present and in close proximity with the implant surface. These observations suggest that the subantral augmentation procedure performed simultaneously with the placement of an HA-coated implant with HA as the graft material apparently resulted in osseointegration between the implant and the surrounding bone. The implant was maintained without complication for 9 years.     

One-stage maxillary sinus elevation using a bone core containing a preosseointegrated implant from the mandibular symphysis

This report presents a novel surgical approach of a one-stage maxillary sinus elevation using a bone core containing a preosseointegrated implant harvested from the mandibular symphysis. As a result, the elevation of the floor of the maxillary sinus and the placement of the implant were achieved at the same time, and the required healing time was significantly reduced. Three months after placement of the implant in the symphysis, a bone core containing the implant was retrieved using a trephine. The bone core was placed in the resorbed posterior maxillary ridge, thereby elevating the maxillary sinus floor. The bone core containing the implant was allowed to heal for 5 months, after which the implant was restored and followed up for 30 months. This technique represents a surgical modification intended to avoid the conventional two-step sinus elevation surgery in which the surgical procedure of graft placement is followed by surgical implant placement. This approach requires significantly reduced healing time and provides an increased bone quality around the implant, which is of clinical importance, particularly in the posterior maxilla.     

Plain film arthrography applied to the diagnosis of intra-articular adhesions of the temporomandibular joint.

PURPOSE: To evaluate the diagnostic accuracy of plain film arthrography (PFA) on the presence of intra-articular adhesions of the temporomandibular joint (TMJ). PATIENTS AND METHODS: The study population included 105 consecutive patients (105 TMJs) and data collected in our department. All patients were examined by PFA and arthroscopy. The findings of interpreting PFA were recorded as positive, suspicious, or negative according to the PFA radiographic criteria. After comparing the findings of PFA with those of arthroscopy, the comparison data were assessed by generating receiver operating characteristic curve (ROC curve) and analyzing the area (A(z)) under the curves with SPSS 11.0 (SPSS, Inc, Chicago, IL), and the area under the ROC curve was calculated. According to the area, the diagnostic value of PFA was evaluated. Meanwhile, the causes of misdiagnosis and underdiagnosis of intra-articular adhesions were analyzed. RESULTS: Arthroscopic surgery results confirmed that 56 TMJs in 105 patients had adhesions. The area under ROC curve was 0.73 (confidence interval, 0.64, 0.82; P < .05). The adhesions located in the medial groove could hardly be detected through PFA, while those located in the lateral two thirds of upper joint compartment could easily be detected. CONCLUSION: Although the diagnostic accuracy of PFA was fair, it was a simple and effective modality to diagnose intra-articular adhesions of the TMJ. The causes of misdiagnosis and underdiagnosis were related to the size and location of the intra-articular adhesions.     

Cranial implant modification

This technique combines the heat-cured resin system with an autopolymerizing resin system (Cranioplast). Cranioplast has been used since the early 1950s. Clinical trials have shown that it evoked the least severe inflammatory response when compared with other autopolymerizing methyl methacrylate systems. The advantage inherent in this technique is the ability to go to the operating room with a prefabricated heat-cured acrylic resin prosthesis and alter the implant with Cranioplast for excellent adaptation to the defect. The technique provides a well-fitting cranial implant prosthesis with good cosmetic results.