[Elimination of defects in the Schneiderian membrane during sinus lift operations]

PURPOSE

Evaluation of the effectiveness of a new method of plasty of an extensive defect in the mucous membrane of the Schneiderian membrane, which occurs during the sinus lift operation, using an artificial collagen membrane and a developed method for fixing it.

MATERIAL AND METHODS

A total of 188 patients took part in the study, all of these patients underwent an open sinus lift operation with simultaneous or delayed implantation. Operations were performed under balanced anesthesia. Six months after the operation, according to computed tomography, the height of the formed bone regenerate was estimated. In the area of each missing tooth, the initial bone height and the resulting bone grafting were assessed. Then we compared the average values before and after the operation, the average height difference before and after the operation.

RESULTS

In 19 patients during the sinus lift there was an accidental extensive rupture of the mucous membrane of the maxillary sinus. Elimination of the mucosal defect was carried out according to our patented method. All 188 patients were diagnosed with partial loss of teeth with bone tissue deficiency in the distal maxillary sinus. The height of the alveolar process in the projection of missing teeth ranged from 0.5 mm to 5 mm. Delayed dental implantation was performed when the height of the alveolar bone was less than 3 mm, direct when the presence of 3-5 mm. After 6 months, dental implants were installed in the reconstruction zone, after another 6 months - rational prosthetics.

CONCLUSIONS

The proposed method of plastic surgery has the following advantages. Firstly, it allows to eliminate the defect of the mucous membrane together with an increase in the height of the alveolar ridge. Secondly, after this method, the integrity of the mucous membrane will be restored. Thirdly, with an alveolar bone height of 3 mm or more, dental implants should also be installed.

Experimental Model for the Study of Reparative Bone Regeneration in the Reconstruction of the Lower Jaw

An experimental in vivo model has been developed on the rabbit mandible to study reparative regeneration of alveolar bone after intercortical split osteotomy and the role of the periosteum in the process of reparative osteogenesis. The peculiarity of this model is fixation of the periosteum over the reconstruction zone, which allows preserving the bone block displaced during surgery and leads to the formation of an organotypic structure of the regenerate with cortical and spongy bone.

Plasma Electrolytic Oxidation for Dental Implant Surface Treatment

Current technologies of plasma electrolytic oxidation (PEO) for modifying the surfaces of dental implants made of the Grade IV titan alloy provide predictable long-term results in implant dentistry. The aim of the study is to evaluate the efficacy of PEO technology comparing two types of surface modification of dental implants made of VT1-0 medical titanium alloy.

Materials and Methods

50 IRIS dental implants (Scientific Production Company LICOSTOM, Russia), 10-mm long and 4 mm in diameter, were manufactured from the VT1-0 alloy. The implant surface was treated by two PEO methods: 1) in the aqueous solution of alkaline electrolyte without any additional modifiers (PEO-Ti); 2) in the aqueous solution of orthophosphoric acid-based electrolyte containing calcium carbonate (PEO-Ca). Implants made of VT1-0 alloy after milling and without additional treatment served as control samples. The implant surfaces were studied by electron microscopy and energy dispersive X-ray spectrometry. Some of the implants were installed in sheep, samples were obtained at 2, 4, and 8 weeks and studied by microcomputer tomography.

Results

Regardless of the electrolyte composition, a highly developed porous surface was formed in the samples with PEO-modified surfaces. The surface of the PEO-Ti samples in a simple unmodified electrolyte was characterized by a large number of open pores with a wide range of size distribution from 200 nm to 3 μm. The pore size distribution was of a monomodal character, with a maximum near 0.23 μm. The PEO samples in the Ca-containing electrolyte had pores also in a wide range from ~80 nm to ~7 μm. The pore distribution, in contrast to PEO-Ti, was bimodal in nature, with the main maximum in the region of 1.05 μm and the concomitant maximum near 2.45 μm.The obtained surfaces of both types (PEO with Ca and Ti) possessed high purity and optimal microroughness for osseointegration. Both types of PEO treatment (PEO with Ca and Ti) have demonstrated a similar osseointegrative potential, nevertheless, the surface of the PEO-Ca showed a better contact with the implant surface (49.8%) than PEO-Ti (42.4%) obviously due to the presence of calcium in its composition.

Conclusion

The PEO-formed implant surfaces demonstrate high osseointegrative properties after any variants of treatment and show the potential for application in osteoporosis.

Digital analysis of stomatognathic system morphofunctional condition in patients with distal occlusion before and after treatment with the Twin Block appliance

Relevance. For many years studies have evaluated the possibilities of modifying the growth of the maxillofacial complex during orthodontic treatment with functional appliances. Despite the large number of studies devoted to orthodontic treatment of distal occlusion in children and adolescents, there is no consensus among orthodontists on the appropriateness, timing and tactics of such treatment.Material and methods. The article presents the results of the treatment of distal occlusion in children and adolescents aged 7-18 years using the Twin Block appliance. The study included clinical, anthropometric, radiographic and functional research methods.Results. The course of treatment eliminated distal occlusion in all groups; in Group 1, the length of the mandibular body was 64.4 ± 2.8 mm before the treatment and 69.6 ± 2.4 mm after the treatment (p = 0.016); in Group 2, the length of the mandibular body was 69.7 ± 6.6 mm before the treatment and 72.5 ± 6.9 mm after the treatment (p = 0.019); in Group 3, the length of the mandibular body was 69.8 ± 5.6 mm before the treatment and 74.0 ± 4.3 mm after the treatment (p = 0.005). The temporomandibular joints did not show pathological changes; most patients (70%) did not demonstrate anterior position of the condyles after the treatment.Conclusion. Orthodontic treatment of patients aged 7-18 years with distal occlusion using the Twin Block appliance is an effective treatment method. The orthodontic treatment with functional appliances is most reasonable during the period of peak growth when significant skeletal changes are possible to obtain.

[Comparative analysis of different types of implant-abutment interface on the basis of three-dimensional finite element analysis data]

The purpose of the study was to perform a comparative static and dynamic finite element analysis of various taper and cylindrical implant-abutment connections in three-dimensional (3D) models including: abutment, fixing screw, implant, cortical bone, cancellous bone. 3D implant model was IRIS LIKO-M system (Russia) 4 mm diameter and 10 mm length. All the models (M1-M6) were built in the same way. While maintaining the external design of IRIS LIKO-M implant, they differed only by taper angle 1.25°, 5°, 9° and its height - 0.45 and 1.85 mm; the models (M7, M8) had a cylindrical connection with a joint height of 0.45 and 1.85 mm. The bone model was 6 mm width, included cortical layer was 3 mm and the inner cancellous bone. The results of static FEA of an occlusal load showed that implant with 1.85 mm abutment connection transfer strain from edge of a cortical bone to its inner layer thus preventing marginal bone resorption. The best results showed implant model with conical taper 5° and 1.85 mm height: the smallest von Mises stress in cortical layer at tightening of the fixing screw and at masticatory load, and the larger margin of safety of an implant, the abutment and the fixing screw. The results of dynamic FEA of implant with cylindrical connection demonstrate that the gap between an abutment and an implant may occur and lead to fixing screw loosening or fracture. At the same time, the implant design with knot of interface of conical type 5° remains tight at dynamic load.

[Mathematical rationale and results of clinical use of IRIS short implants]

The aim of the study was to provide a mathematical justification of the possibility of using 6.5 mm IRIS implants and to evaluate the results of orthopedic treatment in patients with partial loss of teeth. For the calculations was constructed of a composite three-dimensional computer models: the abutment screw-implant-bone. A total of 3 models were prepared: M1-implant in the spongy bone tissue, this model corresponds to the implantation on the HF when replacing one molar; M2-2 implants in the spongy bone tissue located at a distance of 4 mm connected via abutments, this model corresponds to the implantation of RF when replacing two molars; M3-implant in the cortical bone tissue, this model corresponds to the implantation of LF when replacing one molar. Loading of implants was carried out by occlusive force applied to its end surface. The results of the calculations showed that the equivalent stresses and limiting stresses of compression-tension are within the permissible values, which were obtained by us earlier in respect of the irregular implants and are consistent with the results of calculations for other systems of short implants. The clinical part of the work consisted in the treatment of 27 patients with partial loss of teeth, who had 41 iris evolution implants with a diameter of 5 mm, length of 6.5 mm after 3 years, there was a slow bone resorption in the cervical region not exceeding 0.35 mm, which corresponds to generally accepted international standards. During the first three years of operation there were no cases of loss of established implants. Thus, the data of mathematical modeling by finite element method and retrospective three-year analysis of prosthetics on IRIS evolution implants with length of 6.5 mm showed that the use of short implants in the recovery of upper and lower jaw molars is an effective method with a high success rate at long - term and resorption level of 0.34 mm.

[Orthotopic bone implants for bone regeneration]

Biotechnology industry is rapidly developing. The elaboration of new biomaterials for bone reconstruction is one of the most perspective directions in tissue engineering. There are millions of surgical operations associated with use of bone graft materials every year. In this article we tried to analyze and systematize data about advanced technologies and modern trends in the preparation of bio-composite bone graft materials. Special attention is given to 3D-prototyping that allows making bone implants with individual form. Introduction of molecular biology technologies such as activating specific cytokines and growth factors at the right time makes it possible to optimize bone regeneration process. The article has also some suggestions on further improvement of the bone engineering technology.

[Development and preclinical studies of insulating membranes based on poly-3-hydroxybutyrate-co-3-hydroxyvalerate for guided bone regeneration]

Bone tissue damages are one of the dominant causes of temporary disability and developmental disability. Currently, there are some methods of guided bone regeneration employing different osteoplastic materials and insulation membranes used in surgery. In this study, we have developed a method of preparation of porous membranes from the biopolymer poly-3-hydroxybutyrate-co-3-hydroxyvalerate (PHBV), produced by a strain of Azotobacter chroococcum 7B. The biocompatibility of the porous membranes was investigated in vitro using mesenchymal stem cells (MSCs) and in vivo on laboratory animals. The cytotoxicity test showed the possibility of cell attachment on membrane and histological studies confirmed good insulating properties the material. The data obtained demonstrate the high biocompatibility and the potential application of insulating membranes based on PHBV in bone tissue engineering.

[Stress final element analysis at the abatement-implant-bone interface]

According to a research

AIM

we carried out the comparative final element analysis of stress in implant construction and the bone surrounding it. The best result showed implants with platform switching and cone interface between implant and abatement. Such combination of elements allows maintaining implant construction stability and decrease the load on cortical bone.

[Class II malocclusion: some aspects of diagnostics and complex orthodontic and surgical treatment]

Class II malocclusions are of interest to the practicing orthodontists since they constitute a significant percentage of the cases they treat. The process of establishing a treatment plan requires an assessment of therapeutic modifiability. The purpose of this article is to provide a perspective on the characteristics, development, etiology and broad treatment consideration in Class II malocclusions.

[Dental implants in complex oral rehabilitation in patients with class III occlusion and partial teeth loss]

To prove the efficiency of dental implantation in complex treatment of patients with class III malocclusion and partial teeth loss. Nine patients aged 18-35 years with class III malocclusion and partial teeth loss were included in the study. All patients received two-step treatment involving orthodontic correction with two-step implantation and provisional restorations placement followed by orthognatic surgery procedure. The patients were followed-up for three years with no recurrent malocclusion or implant failure revealed, thus proving dental implantation to be useful tool in complex oral rehabilitation of patients with class III malocclusion and partial teeth loss.

[Russian dental implants system LIKO-M - 5 years clinical experience]

The study focuses on long term results of restorative treatment with dental implant system Liko-M. The study included 503 patients examined and 274 patients treated aged 20-69 with partial or complete teeth loss. The patients were examined and treated at the Department of Maxillofacial and Oral Surgery of Nizhny Novgorod State Medical Academy and in 4 dental practices in Moscow and Nizhny Novgorod. Two-staged implantation method was applied. The treatment met esthetic and functional requirements. Marginal bone resorption was estimated as 0,1 to 1 mm within 5 years follow-up. LIKO-M dental implant system thus proved to be efficient both esthetically and functionally and may be used for compete oral rehabilitation of edentulous patients.

[Rehabilitation of patients with deformations after periorbital burns]

The study involved 152 patients with facial burns consequences (including 118 patients with burns of the mouth). Specific post-burn deformities were revealed: I type - deformity of the anatomical unit caused by scar tissue traction from adjacent regions (the unit itself preserved); II type - distortion caused by single scars without significant tissue defect; III type - post-burn deformities with total or subtotal skin scarring; IV type - tissue defects characterized by loss of anatomical unit with deep anatomical structures down to the bone and possible exposition of the paranasal sinuses and face cavities. Such classification based on the amount of tissue loss dictates the choice of surgical technique, allowing optimal functional and aesthetic treatment results.

[Study of testicular cancer gene expression in samples of oral leukoplakia and squamous cell carcinoma of the mouth]

Cancer-testis (CT) antigens are normally expressed mostly in human germ cells, there is also an aberrant expression in some tumor cells. This expression profile makes them potential tumor growth biomarkers and a promising target for tumor immunotherapy. Specificity of CT genes expression in oral malignant and potentially malignant diseases, e.g. oral leukoplakia, is not yet studied. Data on CT genes expression profile in leukoplakia would allow developing new diagnostic methods with potential value for immunotherapy and prophylaxis of leukoplakia malignization. In our study we compared CT genes expression in normal oral mucosa, oral leukoplakia and oral squamous cell carcinoma. We are the first to describe CT genes expression in oral leukoplakia without dysplasia. This findings make impossible differential diagnosis of oral leukoplakia and squamous cell carcinoma on the basis of CT genes expression. The prognostic value of CT genes expression is still unclear, therefore the longitudinal studies are necessary.

[Use of platelet poor plasma for elimination of Schneider's membrane defects arising during sinus lifting]

Topografical anatomical features of maxillary sinus structure create complexities for carrying out the sinus lifting operation. With Schneider's membrane defect from 3 to 6 mm the technique of its elimination with use of platelet poor plasma is offered. Defects in mucous membrane from 3 to 6 mm arise during operation in 7,9% of cases. In such cases bone window is expanding, mucous membrane is mobilizing and the defect is covered with platelet poor plasma received from patient's blood.

[Elimination of Schneider's membrane defects arising during sinus lifting operation]

During the operation of sinus lifting and occurrence of Schneider's membrane defect in the size no more than 3 mm the technique of its elimination is offered. Anatomic features of structure of maxilla sinus and error of surgical technics can lead to intraoperative rupture of a Schneider's membrane. At the size of defect no more than 3 mm are recommended to separate a membrane on all perimeter of the bottom third of sinus and then to lift it up until edges of the damaged mucous membrane will block, <<crawl>> against each other forming a fold, thereby closing defect. The offered method allows to spend successfully sinus lifting as with delayed (in 6 months), and with direct implantation.

['Veneer' plastics of jaw alveolar bone before dental implant placement]

For cases of considerable atrophy of alveolar bone updating method of vinir plastics with iliac crest transplant is offered. The technique of capital GHE, Cyrillic-shaped bone transplant formation is developed. Use of capital GHE, Cyrillic-shaped bone transplant from iliac crest allows increase volume of alveolar part of jaws by height and width. Resorption of bone transplant is reduced by additional use of biomaterials and collagen membrane. Authors received positive results of the delayed implantation after bone plastic.

[Defect elimination of mandible alveolar part by sandwich plastics]

As part of the plan to prepare mandible alveolar part to dental implantation in cases of considerable vertical atrophy several variants of osteoplastic operations allowing to increase the height of mandible alveolar part 2 methods of sandwich plastics were offered by us: sandwich plastics by bone flap elevation and sandwich plastics by bone flap rotation. The operation schemes and operation course description were presented; there were proved positive postoperative results of the vertical bone resorption elimination and results of dental implantation on received bone volume of the jaw.