Alveolar Bone Atrophy Research Articles

Manifestation of Langerhans cell histiocytosis in the oral cavity: The authors’ experience

Abstract Background. Langerhans cell histiocytosis is a rare reactive proliferative disorder marked by excess proliferation and accumulation of mononuclear phagocytes in tissues and organs. Usually, organs and systems where Langerhans cells are normally found are involved. Lesions may be limited to one system and be single- or multisite, or many systems may be involved. The etiology is not fully known. According to one of the hypotheses, immune dysfunction due to exuberant response to an unknown antigen may be the cause. The most common clinical symptoms include skin lesions, bone pain, exophthalmos, and enlarged lymph nodes, affecting the liver and spleen. Gingivitis, pocket granulation tissue, ulceration of the gingival papilla, alveolar bone atrophy leading to loosening and loss of teeth are observed in the oral cavity. The aim of the study was to determine the type and incidence of oral manifestations in patients diagnosed with Langerhans cell histiocytosis. Methods. We evaluated patients’ medical records to obtain data on the children’s age at diagnosis, sex, the form of Langerhans cell histiocytosis, clinical picture (systemic and local oral symptoms), and radiological findings. Dental examinations (clinical and radiological) were performed to assess oral mucosa and periodontal tissues, and medical records were analyzed for the course and treatment of histiocytosis. Results. The analysis included the medical records of 43 patients with Langerhans cell histiocytosis. Oral lesions in the form of gingivitis, pathological tooth mobility, and expansion of alveolar mandibular bone were observed in 7 patients. Conclusions. Langerhans cell histiocytosis may be accompanied by maxillary, gingival, and mucosal lesions.

MRI for the display of autologous onlay bone grafts during early healing-an experimental study.

Objectives:Autologous bone grafts are the gold standard to augment deficient alveolar bone. Dimensional graft alterations during healing are not known as they are not accessible to radiography. Therefore, MRI was used to display autologous onlay bone grafts in vivo during early healing.Methods and materials:Ten patients with alveolar bone atrophy and autologous onlay grafts were included. MRI was performed with a clinical MR system and an intraoral coil preoperatively (t0), 1 week (t1), 6 weeks (t2) and 12 weeks (t3) postoperatively, respectively. The graft volumes were assessed in MRI by manual segmentation by three examiners. Graft volumes for each time point were calculated and dimensional alteration was documented. Cortical and cancellous proportions of bone grafts were assessed. The intraobserver and interobserver variability were calculated. Statistical analysis was performed using a mixed linear regression model.Results:Autologous onlay bone grafts with cortical and cancellous properties were displayed in vivo in eight patients over 12 weeks. The fixation screws were visible as signal voids with a thin hyperintense fringe. The calculated volumes were between 0.12–0.74 cm3 (t1), 0.15–0.73 cm3 (t2), and 0.17–0.64 cm3 (t3). Median changes of bone graft volumes of −15% were observed. There was no significant difference between the examiners (p = 0.3).Conclusions:MRI is eligible for the display and longitudinal observation of autologous onlay bone grafts. Image artifacts caused measurements deviations in some cases and minimized the precise assessment of graft volume. To the knowledge of the authors, this is the first study that used MRI for the longitudinal observation of autologous onlay bone grafts.

The Lateral Border of Scapula for Alveolar Ridge Reconstruction: A Prospective Clinical Study

The purpose of this prospective clinical study was to evaluate the efficiency of alveolar ridge reconstruction with the lateral border of scapula (LBS) prior to implant placement and to assess onlay graft retention and bone resorption during a short term of function. A total of 25 partially or fully edentulous patients with severe alveolar bone atrophy received ridge reconstruction with grafts harvested from the LBS. Histologic analysis of bone grafts was performed. Six months after augmentation, patients underwent CBCT and received dental implants. After another 3 months, healing abutments and implant-supported dentures were placed. Patients were followed for an average of 24 months. Thirteen patients received primary bone grafting from LBS. Twelve patients experienced unsuccessful ridge reconstruction with other grafts before and were secondarily augmented with LBS. The average dimensions of LBS grafts were 6.3 × 2.3 × 1.2 cm. Histologic analysis confirmed the cortical nature of the graft. No donor-site complications occurred, and arm movements were restored within 2 weeks. Following augmentation, two patients had sutures disrupted that healed uneventfully after revision. The average resorption of LBS grafts after 6 months was 12.2% ± 3.0%. At the time of implant placement, the dimension of the ridge was 12.3 ± 2.0 mm and 6.9 ± 1.6 mm in height and width, respectively. The survival rate of the 174 implants placed was 98.3%. LBS can be used as an alternative extraoral grafting site for extensive ridge reconstruction prior to implant placement.

Changes of the atrophic maxillary alveolar bone and treatment success 10 years after placement of implants simultaneously with transalveolar sinus floor elevation; A retrospective analysis

Changes of the atrophic maxillary alveolar bone and treatment success 10 years after placement of implants simultaneously with transalveolar sinus floor elevation; A retrospective analysis

Influence of Bone Anatomy on Implant Placement Procedures in Edentulous Arches of Elderly Individuals: A Cross-Sectional Study on Computed Tomography Images.

To describe the prevalence of alveolar bone atrophy in edentulous arches of elderly individuals in relation to insertion of dental implants and the eventual need for bone grafting procedures. Computed tomography scan files of 228 edentulous arches of elderly patients (ages 65 to 100 years) were evaluated in relation to implant placement. Six measurements per arch were taken on cross-sectional reconstructions. Bone atrophy categories were described, in relation to implant placement, for the anterior and posterior sections of the arches. Six bone sections per arch were evaluated and allocated to the predetermined categories. Prevalence of each type of atrophy was calculated. In the maxilla, only 5.0% of the patients showed a bone anatomy capable of receiving implants without any augmentation both in the posterior and anterior regions; 64.4% showed the need for major reconstruction in both areas. In the mandible, 17.3% of the patients did not require any augmentation in both regions; 9.4% were in need of major reconstruction in both areas. The anterior part of the arches could eventually be treated without any bone augmentation in 10.9% of the maxillae and 72.4% of the mandibles, while minor augmentation was needed in 16.8% of maxillae and 15.8% of mandibles. Most edentulous elderly patients show some degree of alveolar bone atrophy. It is often feasible to insert implants in the anterior mandible to support a restoration. In most maxillary cases, alveolar atrophy calls for augmentation procedures in both the anterior and posterior areas. In elderly individuals, the anterior maxilla often shows bone deficiency interfering with simple implant placement procedures, thus also limiting the use of tilted implants.

Influence of crown-implant ratio on implant success rate of ultra-short dental implants: results of a 8- to 10-year retrospective study.

The use of short implants has been suggested in recent years as an option for facilitating prosthetic restoration in resorbed jawbones. The aim of the present study was to determine how implant success rate is affected in the long term when ultra-short implants are rehabilitated with fixed restorations, resulting in a crown to implant (C/I) ratio of more than 3:1. The study was conducted as an analysis on all patients operated from December 2005 to November 2007 with ultra-short dental implants. All implants were sintered porous-surfaced (SPS) with a length of 5mm and a diameter of 5mm (5 × 5mm) and were restored with a single crown or a fixed dental prosthesis (FDP). Data collected included implant positioning site, crestal bone levels (CBL), and clinical and anatomical C/I ratios, and pre-established success criteria were used to evaluate the success rate of the implants. Statistical analysis was used to determine any significant differences or correlations (p = 0.05). Forty-one patients completed the follow-up and were eligible for this retrospective study on a total of 50 ultra-short SPS implants. The mean follow-up was 9.5years (range 8.3 to 10.2years). Three of the 50 implants failed because they were lost due to peri-implantitis, while all the other 47 met the pre-established success criteria giving an overall implant success rate of 94%. During the follow-up period, the mean peri-implant bone loss (PBL) was 0.41 + 0.36mm. This study shows that ultra-short SPS implants can prove a reliable solution for prosthetic restoration in patients with severe alveolar bone atrophy. In selected patients with a sufficient bone width, ultra-short implants with a resulting C/I ratio of more than 3:1 presented no contraindications. In selected cases, ultra-short implants may represent an alternative to bone augmentation procedures and a long-term predictable solution.

Clinical Performance of Short Expandable Dental Implants for Oral Rehabilitation in Highly Atrophic Alveolar Bone: 3-year Results of a Prospective Single-Center Cohort Study.

Background and Objectives: Oral health-related quality of life (OHRQOL) is compromised during the post-implant healing period, especially when vertical augmentation is required. A long-term trial sought to evaluate a short dental implant system with an apically expandable macro-design. Materials and Methods: Over 4.5 years, patients with limited vertical alveolar bone were consecutively recruited into this prospective cohort study. Implant success rate, OHRQOL (Oral Health Impact Profile (OHIP)-14), implant stability, and crestal bone changes were evaluated. Results: Data from 30 patients (mean age: 64.6 years, range 44–83) were analyzed, which related to 104 implants (53 in the maxilla, 51 in the mandible). Over the mean follow-up (42.6 ± 16.4 months), the implant success rate was 94.7% in the mandible (two implants lost) and 83.6% in the maxilla (four implants lost; p = 0.096), and the prosthetic success rate was 100%. The median OHIP-14 scores improved from 23 (interquartile range (IQR) 9–25.5) to 2 (IQR 0–5; p < 0.001). The mean implant stability quotient (ISQ) was 71.2 ± 10.6 for primary stability and 73.7 ± 13.3 (p = 0.213) for secondary stability, without significant maxilla-versus-mandible differences (p ≥ 0.066). Compared to the baseline, median crestal bone changes after loading were 1.0 mm (IQR 0–1.3) and 1.0 mm (IQR 0.2–1.2) in the maxilla and mandible (p = 0.508), respectively, at the end of the first year, 1.1 mm (IQR 0–1.3) and 1.0 mm (IQR 0.1–1.2) (p = 0.382), respectively, at the end of the second year, and 1.2 mm (IQR 0–1.9) and 1.1 mm (IQR 0.1–1.2) (p = 0.304), respectively, at the end of the third year. Conclusions: In patients with limited vertical bone height, short implants with optimized macro-design constitute a reliable method for functional rehabilitation, avoiding extensive alveolar bone augmentation.

Study on statics and fatigue analysis of dental implants in the descending process of alveolar bone level.

Alveolar bone atrophy can directly cause a decrease in bone level. The effect of this process on the service life of dental implants is unknown. The aim of this study was to determine the failure forms of the two-piece dental implants in the descending process of alveolar bone level, and the specific states of the components during the failure process. The CAD software SolidWorks was used to establish the model of alveolar bone and dental implants in this article. The finite element analysis was used to analyze the statics of the dental implants in the host oral model. The finite element analysis results showed that the stress concentration point of the implant and abutment in the implant system has changed greatly during the descending process of alveolar bone level, and indirectly increased the fatigue life of the same fatigue risk point. At the same time, the dental implants were tested in vitro in the descending process of alveolar bone level. Then, the fracture of the implant system was scanned by scanning electron microscope. The fatigue test results proved the finite element analysis hypothesis the central screw first fractured under fatigue and then caused an overload break of the implant and abutment.

Bone dehiscence formation during orthodontic tooth movement through atrophic alveolar ridges.

To test the null hypothesis that there is no difference in bone dehiscence formation before and after orthodontic tooth movement through an atrophic alveolar ridge. This longitudinal retrospective study evaluated pretreatment and posttreatment cone-beam computed tomography imaging of 15 adult patients. Twenty-five teeth were moved through the atrophic alveolar bone, whereas 25 teeth not subjected to translational movement were considered controls. The distances between the cementoenamel junction and the alveolar bone crest were assessed at the mesial, distal, buccal, and lingual surfaces of all of these teeth. Data were compared using the Wilcoxon test. The Spearman correlation test and multivariate linear regression analysis were also performed. In general, crestal bone height was reduced around 0.5 mm in all groups in every direction. Median buccal dehiscence increased significantly (+2.25 mm) (P < .05) in teeth moved through the atrophic ridge. Control teeth also had buccal crest loss (+0.83 mm), but this was not statistically different from that of the experimental teeth. Lingual dehiscence increased significantly for the experimental (+0.17 mm) and control (+0.65 mm) groups. Mesial bone height decreased more in the control group (-0.44mm) than in the experimental group (-0.14mm). There was moderate correlation between amount of tooth movement and alveolar bone loss. The null hypothesis was rejected as dehiscence increased after tooth movement through an atrophic alveolar ridge, mainly in the buccal plate.

Fifteen-Year Follow-up of Short Dental Implants in the Completely Edentulous Jaw: Submerged Versus Nonsubmerged Healing.

Short implants are a minimally invasive alternative in the management of alveolar bone atrophy. This study aimed to assess the influence of the surgical approach (1-stage vs 2-stage) on the 15-year survival and marginal bone loss of short implants in a fixed complete denture. A retrospective clinical study was conducted in a single private dental clinic that included short implants placed between January 2001 and December 2002. Forty-one short implants supported 18 screw-retained complete dentures. The mean follow-up time was 15 ± 3 years. The surgical approach (1-stage vs 2-stage) did not significantly affect implant survival and marginal bone loss. The implant survival rate was 90.2%. Short dental implants could be predictably indicated to support fixed complete dentures. The implants could be placed through a 1- or 2-stage surgery.

Success and survival rates of dental implants inserted in homologous bone grafts

Background: Alveolar bone atrophy continues to be a challenge in implantology and, as a function of this, is widely discussed in the literature. Although autologous bone graft remains the first option for treatment of these cases, factors such as increased surgical morbidity and limitation in the amount of bone tissue in the donor area motivated new alternatives, such as the use of homologous bone.

Design of a Randomized Controlled Clinical Study of tissue-engineered osteogenic materials using bone marrow-derived mesenchymal cells for Maxillomandibular bone defects in Japan: the TEOM study protocol

BackgroundMaxillomandibular bone defects arise from maxillofacial injury or tumor/cyst removal. While the standard therapy for bone regeneration is transplantation with autologous bone or artificial bone, these therapies are still unsatisfactory. Autologous bone harvesting is invasive and occasionally absorbed at the implanted site. The artificial bone takes a long time to ossify and it often gets infected. Therefore, we have focused on regenerative therapy consisting of autologous bone marrow-derived mesenchymal cells (BM-MSCs), which decreases the burden on patients. Based on our previous research in patients with maxillomandibular bone defects or alveolar bone atrophy using a mixture of BM-MSCs, platelet-rich plasma (PRP), thrombin, and calcium, we confirmed the efficacy and acceptable safety profile of this treatment. In this investigator-initiated clinical study (the TEOM study), we intended to add β-tricalcium phosphate (β-TCP) owing to large defect with patients. The TEOM study aimed to evaluate the efficacy and safety of bone regeneration using mixtures of BM-MSCs in patients with bone defects resulting from maxillofacial injury, and tumor/cyst removal in the maxillomandibular region.MethodsThe TEOM study is an open-label, single-center, randomized controlled study involving a total of 83 segments by the Fédération Dentaire Internationale numbering system in maxillomandibular bone defects that comprise over 1/3 of the maxillomandibular area with a remaining bone height of ≤10 mm. The primary endpoint is rate of procedure sites with successful bone regeneration defined as a computed tomography (CT) value of more than 400 and a bone height of more than 10 mm. Our specific hypothesis is that the number of required regions was calculated assuming that the rate of procedure sites with successful bone regeneration is similar and the non-inferiority margin is 15.0%.DiscussionThe TEOM study is the first randomized controlled study of regenerative treatment using BM-MSCs for large maxillomandibular bone defects. We will evaluate the efficacy and safety in this study to provide an exploratory basis for the necessity of BM-MSCs for these patients.Trial registrationThis trial was registered at the University Hospital Medical information Network Clinical Trials Registry (UMIN-CTR Unique ID: UMIN000020398; Registration Date: Jan 15, 2016; URL: https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000016543).

A retrospective study of an alternative technique for implant repositioning in the maxillary esthetic region.

Implant-bone block segment repositioning may be an option of treatment for patients with vertical alveolar bone atrophy. To assess implant-bone block movement, gingival outcome and the subjective appreciation of patients after an alternative treatment of an implant-bone block segment repositioning in the maxillary esthetic region. Patients who underwent implant-bone block segment relocation in areas of vertical alveolar bone atrophy in the anterior esthetic region were assessed. The outcome measures were implant failure, complications after initial loading, vertical bone augmentation, papilla index, width of the keratinized mucosa, and patient satisfaction. Twenty-five implants in nine consecutive patients were included in this study. During the follow-up period, only one implant failed. Vertical bone augmentation ranged from 3.0 to 8.4 mm (mean 4.9 mm). A significant improvement (P < .001) in the papilla index was observed, improving the esthetic outcome. Six patients (66.6%) had more than 2 mm of keratinized mucosa and all of the patients were satisfied with the treatment. The esthetics and functional gingival outcome of oral rehabilitation in areas with vertical alveolar bone atrophy can be successfully improved with the presented technique, which had a high overall implant survival rate within a short period.

Relationship Between Crestal Bone Levels and Crown-to-Implant Ratio of Ultra-Short Implants With a Microrough Surface: A Prospective Study With 48 Months of Follow-Up.

The aim of this cohort study was to investigate the relationship between crestal bone levels and crown-to-implant ratio of ultra-short implants, after functional loading. Sixty patients with single or partial edentulism and alveolar bone atrophy were enrolled and treated between December 2009 and January 2016. Without using bone-grafting procedures, patients were rehabilitated with ultra-short implants characterized by a microrough surface and a 6-mm length. Clinical and anatomical crown-to-implant (C/I) ratios and crestal bone levels (CBL) were measured after a follow-up period ranging from 12 to 72 months; all peri-implant and prosthetic parameters were recorded. The data collected were statistically analyzed ( P = .05). A total of 47 patients with 66 ultra-short implants were completely followed up according to described protocol. The mean follow-up was 48.5 ± 19.1 months. The mean anatomical C/I ratio was 2.2, while the mean clinical C/I ratio was 2.6 ± 0.6 at baseline and 2.8 ± 0.6 at the last follow-up appointment. Mean CBL as calculated at the baseline was 0.7 ± 0.5 mm, while at the last appointment it measured 1.0 ± 0.5 mm. The overall implant-based success rate was 96.9%, and the mean peri-implant bone loss (PBL) was 0.3 ± 0.3 mm. No statistically significant relationship was found between anatomical or clinical C/I ratio and PBL. Ultra-short implants appear to offer a predictable solution for implant-prosthetic rehabilitation in patients with edentulism and bone atrophy. A high percentage of implants were successful, with minimal crestal bone loss. The high C/I ratio did not appear to influence either peri-implant bone loss or prosthetic complication rates.

Electromyographic assessment of masticatory muscles activity in patients with severe alveolar bone atrophy with implant-supported fixed dental prostheses

Мета роботи – оцінити активність жувальних м'язів пацієнтів з дефектами зубних рядів та вираженою атрофією кісткової тканин у дистальному відділі верхньої щелепи, реабілітованих незнімними зубними протезами з опорою на імплантати, у різні строки спостереження відповідно до застосованих методик. Матеріали і методи. Досліджено ефективність ортопедичного лікування незнімними зубними протезами на імплантатах та електроміографічну оцінку активності жувальних м'язів 67 хворих, які проходили лікування з 2012 по 2017 роки. Чоловіків було 29 (43.3%), жінок - 38 (56.7%), середній вік пацієнтів - 35.7±12 років. Всі пацієнти були з одно- чи двобічними кінцевими дефектами зубних рядів у боковій ділянці верхньої щелепи без вираженої патології пародонту або загальної патології. Ортопедичне лікування проводилось на остеоінтегрованих гвинтових коренеподібних імплантатах. Пацієнтів з дефектами зубних рядів було розподілено на три групи відповідно до обраного методу лікування. Визначалась функціональна активність жувальних м’язів. Результати. Проведено порівняльну оцінку змін функціональної активності жувальних м'язів у пацієнтів з вираженою атрофією дистального відділу верхньої щелепи після застосування різних методів ортопедичного лікування незнімними ортопедичними конструкціями з опорою на імплантати. Швидкість відновлення функціональної активності жувальних м'язів у пацієнтів з вираженою атрофією дистального відділу верхньої щелепи залежить від строків ортопедичної реабілітації та часу встановлення протезів з опорою на імплантати. Зростання показників біоелектричної активності та зменшення асиметрії в активності жувальних м'язів у випадку відкритого синус-ліфтингу з боковим доступом за атравматичною технікою та одночасним встановлення імплантатів, як і у випадку безпосереднього встановлення коротких імплантатів, підтверджує виражену тенденцію до нормалізації функціональної активності жувальних м'язів, необхідної для належної ортопедичної реабілітації пацієнтів з дефектами зубних рядів. Висновки. Відкритий синус-ліфтинг з боковим доступом за атравматичною технікою та одночасним встановлення імплантатів у дистальний відділ беззубої атрофованої верхньої щелепи забезпечує сприятливі умови для швидшої нормалізації активності жувальних м'язів порівняно з традиційним лікуванням. Короткі імплантати є прийнятною альтернативою процедур синус-ліфтингу та мають клінічні та фінансові переваги.

Long-Term Effects of Bone Morphogenetic Protein-2-Loaded Calcium Phosphate on Maxillary Sinus Lift Surgery for Delayed and Simultaneous Dental Implantation.

Maxillary sinus lift surgery (MSLS) is considered to be a useful treatment method for patients with atrophic alveolar bone. Choosing a suitable surgical procedure to simultaneously decrease graft absorption and obtain long-term survival of dental implants is still a challenge. In this study, 20 patients received MSLS with graft of bone morphogenetic protein 2 (BMP2)-loaded calcium phosphate. Dental implants were placed simultaneously in 10 patients receiving MSLS (1-stage group), and in 10 patients receiving dental implants with a 3 to 6 months delay (2-stage group). The effects were evaluated based on clinical and radiographic examination during a 4 to 5 years follow-up. The results showed that only 1 perforation of the maxillary sinus mucosa was observed in 1-stage group, and was patched with a collagen membrane. An average bone gain of 6.8 mm was observed, and all implants exhibited no looseness, peri-implantitis, or fracture, all of which were stable during the follow-up and exhibited nice dental function during a 4 to 5 years follow-up. The loss of peri-implant bone height was 1.12 ± 0.47 and 1.10 ± 0.39 mm, the probing depth of periodontal pocket was 1.79 ± 0.62 and 1.81 ± 0.71 mm, the sulcular bleeding index was 1.63 ± 0.47 and 1.72 ± 0.54 in 1-stage group and 2-stage group, respectively, and no significant differences existed between these 2 groups. These findings implied that BMP2-loaded calcium phosphate may be a suitable material for MSLS, especially for patients with minimal bone height. Clinicians can use the 1- or 2-stage technique based on clinical condition, patients' choice and clinicians' experience. In patients where implants cannot be stabilized for patients with minimal bone height, 2-stage surgery may be more suitable.

Osteointegration of dental implants in augmented bone after bone flap rotation

The article presents clinical case of a patient with partial secondary absence of teeth and maxillary defect because of vertical alveolar bone atrophy. Vertical alveolar ridge augmentation by osseous flap rotation and xenogenous bone block with 10% collagen was performed. Eight months later 4 dental implants with modified surface were placed in the augmentation area. After 3 months 3 implants showed no signs of osteointegration and were removed. Three week later the patient was admitted to ENT department because of maxillary sinusitis symptoms.

State of oral cavity tissues of rats in conditions of modeling metabolic syndrome

The prevalence of the metabolic syndrome has progressively increased in recent years and occurs on average in every fifth adult in the population of developed countries. Metabolic syndrome is a multi-structural complex of pathological changes, so the choice of an adequate experimental model is important in the study of this state. The study was carried out on the model of the metabolic syndrome adequate to the modern human diet and is easily reproducible. Purpose of the study. Assessment of the state of the tissues of the oral cavity of rats and blood serum under experimental metabolic syndrome.Material and methods. White male rats aged 1,5-2 months were used. An intact group (7 individuals) received a standard ration of the vivarium. In the experimental group (7 individuals), the metabolic syndrome was modeled by introducing into the diet of the internal pig fat at the rate of 20% of the weight of the feed and 10% fructose ad libitum instead of drinking water. The duration of the experiment was 70 days. The biochemical parameters of blood serum and tissues, the state of the dentoalveolar system, the parameters of the intercellular matrix of the mucous membrane and the bone tissue of the periodontal rats, as well as the mineral metabolism of bone tissue were evaluated.Results. Conclusions. A diet high in saturated fats and simple carbohydrates led to visceral obesity in experimantal animals, hyperglycemia, increased total cholesterol, hyperuricemia in the presence of cholesterol in high-density lipoproteins, an increase in the number and depth of carious lesions, alveolar bone atrophy, partial collagen degradation (oxyproline) glycosaminoglycans and the disruption of the intercellular matrix of the connective tissue of the periodontium, the mucous membrane of the oral cavity and bone tissue.

Residual Ridge Resorption– Revisited

AbstractThe Residual Ridge Resorption (RRR) is a major unsolved oral disease with unidentifiable characteristics and unwanted squealae causing physical, psychologic, and economic problems for millions of people all over the world. RRR is basically a term used to describe a condition that affects the alveolar ridge after tooth extractions even after healing of the wounds. RRR is a chronic, progressive, irreversible, and disabling disease, probably of multifactorial origin. The possible etiological factors could be divided into four categories: anatomic, metabolic, functional, and prosthetic. The primary structural change in the reduction of residual ridges is the loss of bone or reduction in the size of bony ridge under mucoperiosteum. The reduction in the ridge mainly occurs labially, lingually and on the crest. The reduction of the residual ridge leads to a variety of stages of ridge form, including high well-rounded, knife-edge, low well-rounded, and depressed forms. Alveolar bone atrophy is cumulative and irreversible, since alveolar bone cannot regenerate. It differs from one individual to the other. It also varies at different times and different sites. Some authors feel RRR as a normal physiologic process and not a disease but the cost in economic and human terms makes RRR as a major oral disease that can be described in terms of its pathology, pathophysiology, pathogenesis, epidemiology, etiology, treatment and prevention.

Virtual quad zygoma implant placement using cone beam computed tomography: sufficiency of malar bone volume, intraosseous implant length, and relationship to the sinus according to the degree of alveolar bone atrophy

The objective of this study was to investigate the malar bone volume and length that a zygomatic implant can engage, and the relationship to the sinus according to the degree of alveolar bone atrophy. A three-dimensional evaluation was performed using cone beam computed tomography scans from 23 patients with a totally edentulous maxilla; quad zygoma implants were virtually placed. The predictor variable was the amount of malar bone volume and length that a zygomatic implant can engage. The primary outcome variable was the relationship to the sinus according to the degree of alveolar bone atrophy. Other variables were the residual alveolar bone height to the floor of the sinus and the nasal cavity. The mean volume of malar bone engaged in this sample of 92 zygomatic implants was 0.19±0.06cm3. The implant had an extrasinus path in 60.9% of cases, a parasinus path in 25%, and an intrasinus path in 14.1%. The results suggest that the average volume of malar bone engaged by a zygomatic implant is constant regardless of implant position and the degree of alveolar bone atrophy. As alveolar atrophy increases, the trajectory of the implant becomes more parasinus and intrasinus. The examiners were able to find enough bone to adequately distribute the implants in all cases.