Preoperative and postoperative diagnostic imaging in dental implant treatment is important. Intraoral radiography, panoramic radiography, medical CT and dental CT are used for diagnostic imaging of implant treatment. In particular, dental CBCT has been rapidly spreading due to the combination of panoramic machines. However, although the images are very useful, these imaging methods have specific defects and cautions when performing inspections. If the dentist does not under stand this well, an unexpected misdiagnosis may occur. This paper introduces the points to keep in mind when performing diagnostic imaging for dental implants.
The key roles of implant therapy are to preserve the natural teeth and recover functionality. In order to achieve safe and precise implant placement, local examination and diagnosis of the edentulous area is important. However, because implant therapy is only one of the options for replacing a missing area, the principle of dentistry does not change when implants are applied. In order to decide the treatment planning, whether with or without implants, a comprehensive examination and diagnosis of the entire masticatory system is essential. The most critical step of this process for implant treatment is to determine the etiology of the edentulous. A comprehensive examination should be completed in the sequence of the skeleton, dental arch, supporting tissues and teeth, to identify the issues. Changes of the intra-oral situation over time since the nonedentulous arch must be identified so that possible changes in the future can also be predicted. Implant placement with advanced techniques following scientific evidence, but without understanding the etiology, might result in a poor prognosis or more complex situation.
This paper discusses the diagnosis, treatment planning and results of implant treatments for patients who have issues in their skeleton and dental arch.
In recent years, the quality of life of patients who have lost teeth because of severe periodontitis has been improved due to the increasing popularity of implant therapy. However, the biggest concern after implant treatment for patients who have suffered from severe periodontitis is the development of peri-implantitis. Long-term follow-up studies have shown that the incidence of peri-implantitis is higher among patients with a history of periodontitis compared to those without. Having a history of periodontitis, as well as smoking habit, is considered to be a risk factor for peri-implantitis.
When providing implant therapy in a patient with severe periodontitis, the following characteristics of the patient need to be considered：1) deep periodontal pockets and infra-bony defects in the teeth, 2) significant alveolar bone loss of the edentulous ridge, 3) an increased mobility of residual teeth resulting from a reduction of supporting bones, 4) the possibility of malocclusion resulting from pathological tooth migration, which exacerbates periodontal disease, and 5) the possibility of tooth loss resulting from periodontal disease that has progressed due to malocclusion.
A combination of these five characteristics could aggravate the decline in ability to cleanse periodontal tissues and peri-implant tissues, resulting in traumatic forces to implant prostheses and natural teeth. Therefore, when providing implant therapy to patients with severe periodontitis, in order to gain long-term stability after treatment, it is particularly necessary to make a detailed diagnosis and prepare a comprehensive treatment plan. Such a treatment plan must be followed by distinct periodontal treatment, reconstruction of hard and soft tissues around the implants, and establishment of a stable occlusal relationship.
The purpose of prosthetic treatment is to try to improve the main complaint of the patient and achieve recovery of the form and function that have been lost. To do so, comprehensive dental treatment should be provided. However, it is not always possible to provide all patients with the treatment that the dentist considers ideal. It is also impossible to completely eliminate the causes of collapse or the risks, even if comprehensive treatment is provided. Therefore, the most important point is to diagnose while predicting the causes of collapse based on various factors, and to reflect the risks in the treatment policy. While the risks are roughly classified into environmental factors, biological factors and composite factors, the environmental and composite factors that are variable need to be understood by the patient sufficiently to ensure stability after the treatment.
The major hindrances to long-term durability after prosthetic treatment are infection and force. Damages caused by force, in particular, must be taken into consideration, especially after installing an implant prosthesis. The types of force can be roughly classified into pathogenic occlusion, parafunction, excessive force, and dietary habit. Even though they may all be categorized as forces, which factors caused adverse effects and resulted in collapse must be analogically inferred, since there are differences among patients. Treatment is then provided to improve these factors by using measures that are practical and feasible while always taking into account the priorities. It is recommended that the treatment policy should be determined with consideration of various elements, including the values, economic background and age of the patient.
No effective and sustainable measures against forces that are highly harmful have been identified. Even so, it is necessary to steadily and repeatedly communicate and share the risks with the patient.
We must face our patients while keeping in mind that there is one diagnosis and diverse treatment policies.
The present study investigated the influence of the connection angle between the implant body with 20° and 30° inclinations, morse taper abutment (8° and 10°) and crown-to-implant ratio (C/I = 0.93 and 1.33) on the maximum bending load and strain of the collar. The following results were obtained.
The maximum bending load of the implant (C/I = 0.93) with 20° and 30° inclinations was larger with the connection angle of 8° than 10°. However, there was no influence of the connection angle on the extent of deflection. In contrast, there was no influence of the connection angle of the implant (C/I = 1.33) with 20° and 30° inclinations on the maximum bending load or deflection.
Under the conditions of a 20° inclination angle and C/I = 0.93, 0.1％ strain of the collar was confirmed. A 400 N load was applied with a connection angle of 8°, and a 300 N load was applied with a connection angle of 10°. Under the condition of a 30° inclination angle, a 200 N load was applied with connection angles of both 8° and 10°. Under the conditions of a 20° inclination angle and C/I = 1.33, more than 0.1％ strain of the collar was confirmed. A 350 N load was applied with a connection angle of 8°, and a 300 N load was applied with a connection angle of 10°. Under the condition of a 30° inclination angle, 0.1％ strain of the collar was confirmed when a 200 N load was applied with connection angles of 8° and 10°. The amount of strain of the implant of 20° inclination, compared with under the 800 N load in C/I ratio 1.33 was the almost same as that of the implant of 30° inclination under the 450 N load.
The inclination angle and C/I ratio were large during implant placement, and the maximum bending load was small for both connection angles (8° and 10°). The strain of the collar was marked when a low load was applied.
These results suggest that the inclination angle, superstructure height and connection angle of the abutment should be considered at implant placement.
Purpose : The adsorption of proteins onto a Ti implant surface is the first biological event after bone implantation. Thus, the investigation of protein adsorption to Ti is vital for understanding the process of osseointegration. In this study, using the quartz crystal microbalance (QCM) method, we investigated the adsorption of proteins to a Ti surface in two-step adsorption methods.
Method : A 27 MHz QCM apparatus was employed. The following two-step adsorptions of fibronectin (Fn) and albumin (Alb) were investigated : (1) Fn-Alb series : First, the Fn solution was injected into the phosphate-buffered saline (PBS) solution, followed by the Alb solution ; (2) Alb-Fn series : First, the Alb solution was injected, followed by the Fn solution. The frequency decrease was monitored for 60 min after each protein injection. The adsorbed amounts of Fn or Alb in each series were calculated using the Sauerbrey equation. The apparent reaction rate, Kobs, was obtained by curve fitting of the frequency decrease curve. Atomic force microscopy was used to observe the surface appearance and surface roughness of protein-adsorbed sensor surfaces after they were rinsed with double-distilled water.
Results : Fn injection produced greater frequency decrease than Alb injection. Alb-Fn series showed greater frequency decrease 120 min after protein injection than Fn-Alb series. The adsorbed amount of Fn in Fn-Alb series is significantly higher than that of Alb in Alb-Fn series during the first adsorption in each. Moreover, there is a significant difference in the adsorbed amounts of Fn between the first step in the Fn-Alb series and the second step in the Alb-Fn series. There are no significant differences in the adsorbed amounts of Alb between the first step in the Alb-Fn series and the second step in the Fn-Alb series. The first protein adsorption showed significantly greater Kobs values than the second protein adsorption. AFM images showed that after rinsing with water, some Alb remained on the Alb-adsorbed sensor surface, but little Fn was identified. The Alb-adsorbed sensor surface showed significantly greater Sa values than native Ti and Fn-adsorbed Ti surfaces.
Conclusion : The adsorption of Alb influences that of Fn in two-step adsorption. The adsorbed amounts of Fn were enhanced by Alb adsorption, but the adsorbed amounts of Alb were not influenced by Fn adsorption. Fn and Alb adsorption rates were delayed by first protein adsorption, revealing that the first protein adsorption influences the second protein adsorption.
Recently, zirconia (ZrO2) has gained increasing importance and popularity as an implant material in addition to titanium (Ti). Fibronectin (FN) consists of cell-adhesive molecules that enhance the adhesion and migration of cells. The specific binding of FN on the surface of Ti or ZrO2 may serve to enhance the osseointegration and biological sealing at the epithelium-implant interface. Accordingly, it is important to analyze the response and application of FN to Ti and ZrO2 surfaces. Superhydrophilic surface modification with plasma treatment is reported to enhance the adsorption of the proteins to implant materials. This study aimed to evaluate the binding behavior of FN on the plasma-treated ZrO2 surface in comparison with the Ti surface. In addition, the mechanism of enhancement of the adsorption of FN is considered by surface analysis.
Atmospheric-pressure plasma treatments were performed to a Ti or ZrO2 sensor (Ti-Plasma, ZrO2-Plasma) that was designed for quartz crystal microbalance (QCM-D) apparatus. An untreated titanium sensor (Ti-Air, ZrO2-Air) and gold sensor (Au-Air) were used as controls. Laser scanning microscopic observation, X-ray photoelectron spectroscopic analysis (XPS), contact-angle measurement and evaluation of surface energy were performed. Subsequently, adsorption behavior of FN was assessed using the QCM-D method. Surface energy, and in particular, cp components in the Plasma group, were increased compared to those in the Air group. The amount of FN adsorption was increased in the Ti-Air and ZrO2-Air groups compared to Au-Air. In addition, the specific binding of FN was increased in the plasma-treated groups (Ti-Plasma and ZrO2-Plasma) compared with the untreated groups (Ti-Air, ZrO2-Air). No apparent differences in FN adsorption were recognized between the Ti and ZrO2 groups. The reason was considered to be that similar kinds of oxides and hydroxyl groups were detected on both Ti and ZrO2. The amount of FN adsorption was increased in the plasma-treated groups, because the carbon contents were decreased and basic-hydroxyl groups with positive charge were increased by the plasma treatment, leading to an increase in the amount of FN adsorption that has negative charge.
These results suggested that FN adsorption behavior is almost the same between Ti and ZrO2 and that plasma treatment may promote the adsorption of FN to titanium and ZrO2.
The purpose of this study was to evaluate the accuracy of intraoral scanners by comparing the trueness and precision of two types of intraoral scanner and one type of extraoral scanner in measuring the distance between pairs of ball abutments in a model with multiple implants.
Four implants were placed on a lower jaw model for dental implant training. After ball abutments were attached to the implants on the reference model, the three-dimensional (3D) shape of the model was measured using a 3D coordinate-measuring machine. Subsequently, the 3D shape data of the model were obtained using two types of intraoral scanner (3M True Definition Scanner [TDS] and 3Shape Trios3 [TR3]) and one type of extraoral scanner (KaVo ARCTICA Auto Scan [KA]). Using the obtained 3D shape data, the trueness and precision in measuring the distance between pairs of the four ball abutments were compared among the scanners using 3D analysis software.
The intraoral scanner group had a greater error in the trueness and precision of the measurement site between the ball abutments than the extraoral scanner. The error in measurements with the intraoral scanners tended to increase with the distance between the ball abutments. Regardless of the distance, the extraoral scanner offered stable trueness and precision.
It is difficult to apply the current optical impression method using an intraoral scanner to a large number of missing teeth from the viewpoint of trueness and precision. The present findings suggest that intraoral scanners could be used for patients with a few missing teeth.
Object : We report a case of medication-related osteonecrosis of the jaw (MRONJ) accompanied by peri-implantitis suspected to involve Sunitinib, with good results obtained by surgical treatment.
Summary : Three years after implant treatment, the patient developed a kidney cancer, and Sunitinib, a molecular targeted drug, was used. Six years later, MRONJ with peri-implantitis developed in the bilateral mandibular jaw.
History : In September 2010, the patient visited our hospital for the purpose of implant treatment and implant placement was performed in November. Sunitinib administration was started in March 2016 due to bone metastasis of kidney cancer. There was swelling of peri-implant mucosa in the bilateral mandibular molar sites and continuous discharge of pus was observed in May 2016. Therefore, the implant was removed under local anesthesia in July 2017. Since the sequestration was confirmed by X-ray, bilateral mandibular humus removal was performed in December 2017 under general anesthesia. Eighteen months after surgery, there is no recurrence of inflammation and a good result has been obtained.
Discussion and conclusions : Regarding the course of this case, hospital visits to our department were discontinued, and during the period of perioperative oral management at another hospital, appropriate maintenance was not performed, oral hygiene was reduced, and peri-implantitis developed. It is presumed that administration of Sunitinib overlapped with osteonecrosis of the jaw. At the time of implant placement, it is difficult to predict the possibility of future use of molecular targeted drugs. It is suggested that the number of elderly and cancer-bearing patients will increase in the future, and implant treatment should be provided while taking such cases into consideration.
We solved the problem of a dental implant in a patient residing in a care home. An 86-year-old female patient had lost her prosthesis supported by an implant. The exposed abutment had injured her lips and tongue, so her visiting dentist asked us to remove the abutment. After we removed the abutment, the patient no longer feels pain due to injury and can comfortably handle her removable denture.
We report a successful case of a mandibular implant overdenture for a patient whose newly constructed implant overdenture was matched to the old denture by using digital computer aided design (CAD) and the metal reinforcement was also digitally designed (CAD) and fabricated by the laser sintering method.
The patient was a 62-year-old male with the chief complaint of fracture of the mandibular implant overdenture without metal reinforcement. He was satisfied with his present denture, so we repaired it and fabricated a duplicated denture in order to make a new denture. After digitizing the duplicated denture by using a model scanner, the metal reinforcement was also digitally designed (CAD) and fabricated by the laser sintering method using Co-Cr alloy. The new denture was fabricated to be the same as the present denture. One and a half years have passed, there has been no fracture of the denture, and the clinical results are good.
Aim : There have been few studies on the incidence of dental implant fractures among patients treated with implant pros theses in dental practitioners' clinics in Japan. The aim of this study was to investigate the incidence of dental implant frac tures and fracture-related factors in 10 private dental clinics in Kyushu.
Materials and method : We mailed a questionnaire to 10 dental clinics which were members of the Fukuoka Oral Implant Research Association and asked the clinics to fill out the questionnaire based on information as of March 2018. The questions included the number of patients who had completed implant treatments, the number of implants used in the treatments, and the number of fractured implants among those that had been placed at the responding clinic.
Results : An evaluation was performed on 9,814 implants placed in 4,392 patients at the 10 dental clinics. Implant fractures were observed in 17 implants (0.17%) in 16 patients (6 males and 10 females) whose mean age was 69.4 years (range 42-91 years). The positions of the fractured implants were as follows:8 in the maxilla and 9 in the mandible, and 10 in the first molar sites, 2 in the second molar sites, 4 in the second premolar sites and 1 in the canine site. Among the fractured implants, 9 supported single crowns, 5 supported two-unit crowns, and 3 supported overdentures. There were 16 implants that frac tured at the platform and 14 of them fractured vertically; only one implant fractured horizontally, at the implant thread area. Bone resorption was radiographically observed in 14 implants with bone resorption around the implant marginal areas but could not be determined in 3 implants because of unclear X-ray radiographs. The fractured implants functioned for 72.3 months on average.
Conclusions : When placing dental implants in the molar region, we should carefully select the size and number of the im plants, implant-abutment connection modes and materials of the implants considering the patient-related factors such as bruxism.
Purpose : Dental implant treatment has become established as an effective method with a good prognosis. However, prob lems of complications are spreading with the growing availability of implant treatment. Especially, complications in maxillary implant treatment can be severe due to the specific histological and anatomical properties. On the other hand, the recent progress and spread of diagnostic equipment is expected to help reduce complications. In this study, a questionnaire survey was conducted to clarify the current status of complications, treatment techniques, and the spread of equipment.
Method : A questionnaire survey of complications in maxillary implant treatment and medical equipment was conducted, targeted 51 certifying and supervisory doctors of the Japanese Society of Oral Implantology in Hokkaido for three years (April 1, 2012 to the end of March 2015).
Results : The complication rate of maxillary sinusitis was 57% in supervisory doctors and 36% in certifying doctors. Perfo ration of the maxillary sinus floor mucosa was 57% in supervisory doctors and 33% in certifying doctors. 93% of supervisory doctors and certifying doctors perform a CT-scan examination before surgery. 79% of supervisory doctors and certifying doc tors perform diagnosis using simulation software. 49% of supervisory doctors and certifying doctors perform computer-guided surgery.
Discussion and Conclusion : Many complications of maxillary implant treatment were related to the maxillary sinus. The introduction of digital equipment was found to be progressing rapidly. The progress and spread of digital diagnostic equip ment is expected to reduce the incidence of complications, but complications of maxillary implant treatment are still experi enced with a high probability by supervisory doctors and certifying doctors.