Dental Fixation Research Articles

Antiadhesive Properties of Imidazolium Ionic Liquids Based on (-)-Menthol Against Candida spp.

Infections with Candida spp. are commonly found in long-time denture wearers, and when under immunosuppression can lead to stomatitis. Imidazolium ionic liquids with an alkyl or alkyloxymethyl chain and a natural (1R,2S,5R)-(−)-menthol substituent possess high antifungal and antiadhesive properties towards C. albicans, C. parapsilosis, C. glabrata and C. krusei. We tested three compounds and found they disturbed fungal plasma membranes, with no significant hemolytic properties. In the smallest hemolytic concentrations, all compounds inhibited C. albicans biofilm formation on acrylic, and partially on porcelain and alloy dentures. Biofilm eradication may result from hyphae inhibition (for alkyl derivatives) or cell wall lysis and reduction of adhesins level (for alkyloxymethyl derivative). Thus, we propose the compounds presented herein as potential anti-fungal denture cleaners or denture fixatives, especially due to their low toxicity towards mammalian erythrocytes after short-term exposure.

DETERMINATION OF CHEWING EFFICIENCY IN PATIENTS WITH RESTORED TOOTH CROWN PART

Supporting teeth preservation at the restoration of dentition defects with the help of fixed porcelain fused metal dentures is considered one of the most important issues of prosthodontics.
 Margin line preparation strategies are still disputable nowadays. In most cases preparation is confined to the ledge creation. Its function is to provide a smooth transition of orthopedic restoration to a tooth root and prevent the traumatization of marginal paradontium.
 These issues are gaining a momentum when the possibility of manufacturing fixed prosthesis with the use of partially or completely ruined teeth with the preserved root as a support appears.
 Since the opportunities of thermal method for gingiva retraction and marginal line formation around the supporting teeth are not studied enough in modern scientific sources, our research aims to define the mastication efficiency state in patients of sample groups after the fixation of dentures on the supporting teeth prepared for prosthesis with the help of diathermocoagulation and mechanical retraction.
 The authors of the article have determined the mastication efficiency in the patients with the restored tooth crown. Altogether 54 patients of two sample groups aged from 20 to 60 years and above with completely ruined tooth crowns were examined. Their soft tissues around the supporting teeth were prepared for the fixed prosthesis manufacturing.
 The first sample group involved 29 patients that made up 53.7% of general studied population. Their supporting teeth gingiva margins were retracted with the help of diathermocoagulation while preparing them for the fixed dentures. While the gingiva margins of the patients of the second sample group, consisting of 25 people (46.3% of general studied population), were retracted with the help of cotton Ultrapak cord, produced by Ultradent (the USA). It is offered in several size options.
 Mastication efficiency state after prosthesis was determined with the help of mastication test (Ukrainian Utility Patent # 94841). In this case, mastication index was the main diagnostic tool. It was received with the help of computer analysis of digital samples in software “Adobe Photoshop Extended”.
 The analysis of the dynamics of mastication test indices of the patients of sample group 1 delivered typical results. In a week after the fixation of fixed porcelain fused metal dentures, the reduction of the mean value of mastication test index by 0.2 was fixed. The verification of these changes according to the statistical significance showed positive result (at p = 0.0004). At the same time, the verification of the changes, occurred during the period from the 7th to the 30th day after the fixation of dentures in patients of sample group 1, with the help of Wilcoxon test showed that at p = 0.9 the reduction of the mean value to 5.148 had no statistical significance.
 While the dynamics of mastication test changes in sample group 2 looked as follows. The reduction of the mean values of mastication test index from 5.184 to 5.112 was observed. So, the spread between the values received before the retraction and in seven days after crown fixation made up 0.072. The conducted statistical verification of these changes (at p = 0.01) proved their statistical significance. In contrast, the collation of the indices received after seven days of denture fixation and in 30-days period after it (from 5.112 to 5.132) at p = 0.961 demonstrated changes at the level of statistical error.
 According to the received research results, prosthesis with the fixed porcelain fused metal dentures promotes patients’ mastication efficiency restoration. That is traced in the reduction of the mastication test index values received after the 7th day of crown fixation in both sample groups. It should be noted here, that statistically significant difference between the indices of the patients of sample group 1 and 2 was not found. On the 30th day of denture fixation, mastication efficiency indices remained almost the same.

Evaluation of denture adhesive cream properties depending on the contact area between denture base and oral mucosa

BACKGROUND: The relevance of this study is that in many countries around the world, and in Russia in particular, the increasing trend toward an aging of population makes problems in dentistry urgent, among which the significant increase in the use of removable dentures is important. The probability of the complete or partial loss of their own teeth is increasing, therefore, the number of removable dentures and the problem of stabilization, adaptation and fixation arises. Factors such as the stabilization and fixation of removable dentures depend on certain anatomical conditions of the denture bed, but due to the lack of optimal conditions, especially in patients with a complete lack of teeth, the latter have to resort to additional means (adhesives) that are used to improve the fixation of removable dentures.
 AIM: The purpose of this study was to evaluate the adhesive properties of the preparation for fixation during prosthetics with removable structures, depending on the area of the base adjacent to the prosthetic bed.
 MATERIAL AND METHODS: Was used a device consisted of a laboratory tripod, a coil, a metal cylinder and a plastic disc are presented in the aricle. However, the bottom of a cylinder is lined with bioskin that simulates oral mucosa tissues. A dynamometer with an option to measure maximum results was used to measure the adhesion force. The adhesive properties of adhesive cream, containing carboxymethyl cellulose and Poly (methyl vinyl ether-alt-maleic acid) were evaluated in 3 stages. Adhesion was examined on a dry surface, on a surface moistened with distilled water, and on a surface moistened with artificial saliva. First, the adhesion value was determined immediately after application of the fixation cream and then after 2 minutes of exposure to the adhesive cream.
 RESULTS: It was found that the contact area of the denture base and oral mucosa equal 55,6%, is the limit percentage of the nonconformity, that can be compensated by using Corega adhesive cream (GSK, UK) only with sufficient moisture content of the oral mucosa and a two-minute exposure of the denture adhesive.
 CONCLUSIONS: The adhesion strength of the means for fixing removable prostheses increases after wetting the studied surfaces. It is established that the symmetry of non-congruent sections on the basis of the prosthesis can increase the adhesive stability of the entire removable structure.

Treatment of gunshot-related mandibular fracture with splint-guided reduction: Case report

Background/Aim: Gunshot injury-related mandibular fractures often have a complex pattern, characterized by comminution, bone loss, and soft-tissue avulsion. The management is difficult and varies between individual cases. Case Report: A 41-year-old male patient presented with marked swelling and ecchymosis in the left mandibular region. Intraorally, he had a deviated open bite on the left side. A unilateral comminuted mandibular fracture was diagnosed by panoramic radiograph and computed tomography. An acrylic dental splint-guided open reduction and internal fixation, including intermaxillary fixation through brackets and intermaxillary elastics, was planned. No complications were observed throughout the healing period, and healing at the fracture site was satisfactory. The occlusion returned to the pre-injury position and was stable. Conclusions: This case report shows that successful functional and esthetic results can be achieved with a strict patient-specific treatment protocol for a comminuted mandibular fracture due to gunshot injury.

Results of stress-strain states study in prosthetics of different types of atrophy of edentulous mandible

Complete dentures remain still popular due to the economic component of such prosthetic treatment. However, additional fixation on intraosseous implants provides a greater clinical and functional effectiveness and a greater level of satisfaction with the results of prosthetics in edentulous patients. At the moment, the biomechanical aspects of complete denture prosthetics and prosthetics with fixation on implants, taking into account the degree of atrophy of the edentulous jaws, are not complete understood. Such studies make it possible to create recommendations on the choice of prosthetic tactics for edentulous patients. The aim of the research was to study the distribution of stress-strain states in prosthetics of the edentulous mandible with complete dentures and with designs supported on intraosseous implants, taking into account the type of atrophy. It was carried out computer simulation of 8 virtual finite element models of mandible with different types of atrophy. According to Keller they were 4 models: of the biomechanical system simulation "complete denture – mandible" and 4 ones – "denture – intraosseous implants – mandible". In each of the models, a chewing load of 100 N was simulated (symmetrically and asymmetrically). The ANSIS 12.1 finite element analysis was used to calculate the stress-strain states in the described calculation systems. It was estimated the distribution of stresses in cortical bone and displacements of the dentures on the prosthetic bed. Under using complete dentures, the maximum stresses in the bone tissue of the prosthetic bed were observed for the third type of mandible atrophy with all types of power load, the smallest ones – for the fourth type. Additional fixation of removable dentures in simulation models of biomechanical systems “denture – intraosseous implants – mandible” lead to a significant increase in stresses in the alveolar bone. The maximum stresses were observed in the area of the marginal bone, while their greatest values were in the well-expressed alveolar part of the mandible for first and third types by Keller. The movements of bases of complete dentures were insignificant and fluctuated within hundredths of a millimeter for all types of atrophy. The use of intraosseous implants for fixation of dentures caused increase in movements by several times. Besides, displacement fields were characteristic: they were uniform for complete dentures but in the use of implants – not. The expressed alveolar process in the first and third types of atrophy of the edentulous mandible caused an increase in the displacements of the distal sections of the dentures on both sides with a symmetrical force load and on one side – with an asymmetric one. It can be assumed that such a distribution of stress-strain states accelerates atrophy of prosthetic bed tissues. As a result of prosthetics of complete defects of lower dentitions, both with traditional complete dentures and with additional support on implants, different distribution of stress-strain states occurs in different phases of the chewing act in the bone of the prosthetic bed, the character of which is determined by the shape of the alveolar part described by Keller's classification. The results allow us to develop an algorithm for determining the kind of prosthetics for edentulous patients, depending on the type of mandible atrophy.

Orogastric intubation with dental fixation for enteral nutrition: a proof-of-concept study

In this crossover trial, we evaluated a new technique for enteral nutrition using orogastric intubation. Twelve volunteers were randomly assigned to both orogastric (OGI) and conventional nasogastric intubation (NGI) with a 15-day interval. The tip of the orogastric tube was fixed intraorally into an upper molar. Participants were asked to remain intubated for 24 hours and rated efficacy and safety using a Likert scale (1: worst / 10: best). Tolerance in hours was longer during OGI (median 21 versus 12.5; p=0.022). OGI was superior in comfort (median 7 versus 3; p=0.002), aesthetic (median 10 versus 1; p=0.002), speech (median 5.5 versus 3; p=0.014) and swallowing (median 8 versus 2; p=0.004). Both procedures were tolerated with mild local complaints. Diet volume through the tube was greater during NGI (p = 0.014). In healthy participants, orogastric intubation with dental fixation showed greater efficacy and similar safety to nasogastric intubation. Clinical trials numberNCT03670238.

Features of patient adaptation during orthopedic rehabilitation based on an assessment of the quality of life and the degree of fixation of removable plate prostheses

Objective : The study objective is to establish the features of patient adaptation during orthopedic rehabilitation on the basis of assessing the quality of life and the degree of fixation of removable plate prostheses. Methods : 64 patients with complete absence of teeth were examined (the 1 st group – 32 people with a prosthesis life of up to one year, the 2 nd group – 32 people with a prosthesis wearing duration of one to two years). The quality of life and the effectiveness of orthopedic rehabilitation were determined using the index of fixation of a removable prosthesis. Results : After treatment, an improvement in the quality of life was observed in patients of both groups. Differences in quantitative estimates of the criteria for prosthesis fixation in patients with different lengths of wearing were established. Conclusions : The presented data indicates an improvement in the quality of life and the degree of fixation of complete removable laminar dentures after orthopedic treatment.

RESULTS OF TREATMENT OF EDENTULOUS PATIENTS WITH DENTURES MADE OF «FTORAX»

Background. The problem of providing high-quality dental care to edentulous patients remains one of the most important and unresolved to this day in the clinic of prosthodontics. The causes of complete loss of teeth can be both periodontal tissue diseases and diseases of hard tooth tissues of carious and non-carious origin, trauma and the like. It becomes necessary to fabricate complete removable dentures to prevent the occurrence of pathologies in such situations. Complete secondary adentia leads to a large number of local and general complications. The chewing apparatus undergoes a number of functional and morphological changes. Therefore, the complete absence of teeth sets the dentist the task of restoring the functions of full chewing, the appearance of the patient, and speech. The complexity of high-quality prosthetics for edentulous patients is also because the clinical characteristics of supporting tissues are diverse, constantly changing, so a personal approach to creating stable denture is needed. It should be added that the fabrication of high-quality complete removable dentures largely depends on the properties of the base material. The main group of materials for the fabrication of such dentures is acrylic plastics.
 The aim. The work is focused on the study of the functional state of the masticatory muscles and the restoration of masticatory effectiveness in edentulous patients, for whom dentures were made in the prosthodontics clinic from the acrylic base material «Ftorax».
 Material and methods. Hot curing plastic based on fluorine-containing acrylic copolymers «Ftorax» was used in the work. Our evaluation of the quality of all constructions was carried out using the «BOFSAS» test, determining the biopotentials of the masticatory muscles using electromyography, and determining the masticatory effectiveness according to I.S. Rubinov.
 Results. Based on our work, it can be noted that the use of the basic acrylic material «Ftorax» allows us to achieve good fixation and stabilization of complete removable dentures, which is subjectively confirmed by the «BOFSAS» test, objectively – by the electromyographic studies and time indices during chewing test according to I.S. Rubinov.
 The amplitude during volitional compression is 556.90±8.72 μV, which approaches the norm (641.58±10.01 μV), and almost four times higher than before prosthetics (188.11±8,13 μV) after 1 year of constructions using. A similar pattern is observed with arbitrary chewing: the amplitude (547.32±8.43 μV) approaches normal (643.92±9.11 μV) compared with the results before prosthetics (201.40±9.39 μV). As for the coefficient «K», its value decreased almost twofold compared with the results before prosthetics (2.44±0.14) and equals to 1.25±0.03, which is significantly closer to normal (1,02±0.01).
 After the test by Rubinov the following results were obtained: the average time that patients with intact dentitions spent chewing on the stimulus was approximately 12.97±0.13 seconds and the average time for patients before prosthetics (with old dentures) was approximately 45.16±0,41 sec.
 The time that patients spent chewing a nut after 1 month was 28.97±0.42 seconds, after 6 months – 26.94±0.44 seconds, and after 1 year of using the entures – 25.48±0.45 sec.
 Based on this, it can be summarized that adaptation to such dentures takes place at the appropriate time with minor corrections.
 Conclusion. The results of our clinical study indicate the feasibility of using «Ftorax» in prosthodontics clinic for treatment of edentulous patients.

ELECTROMYOGRAPHY INDICATORS IN DIFFERENT PERIODS OF USING OF THE REMOVABLE DENTURES IN PATIENTS WITH ACRYLATE INTOLERANCE

Despite the achievements in medical rehabilitation of patients with partial and complete absence of teeth, rehabilitation is not a definitely settled issue for orthopedic dentistry. According to the World Health Organization, about 26% of patients do not use full dentures for various reasons. The most common reasons for non-adaptive removable dentures are poor denture fixation or pain under prosthesis, which may be associated with the development of prosthetic stomatitis. We elaborated a method for the prevention and treatment of prosthetic stomatitis (toxic and allergic), using the magnetron coating with fullerene C60 surface of the prosthesis base.
 The aim of the research is the study of bioelectric activity of the masseter muscle in patients with manifestations of intolerance to acrylic base plastic after covering the prosthesis base with C60 fullerene in the observation period of up to 3 months.
 Material and methods of the research. We examined 29 subjects who presented to the orthopedic dentistry clinic for restoration of dentitions, using of partial and full laminar removable dentures. Patients were divided into 3 groups. The first group embraced patients with complete dentitions without dentures (9 people). The second group comprised patients who used partial and complete removable dentures with acrylic base for 1-3 months and they were diagnosed with prosthetic stomatitis (10 people). The third group included patients, implanted with partial and complete laminar removable dentures with the phenomena of prosthetic stomatitis, which underwent isolation of the prosthesis base using magnetron nano-coating with C60 fullerene (10 people).
 The functional state of the masseter muscles was determined by superficial electromyography, taking into account the condition of the prosthetic bed tissues and the period of using the dentures with nano-coating for 1 day, 15 days, 30 days and 2 months after denture placement.
 Results of the studies and their discussion. As shown by our studies, patients who used partial and complete removable prostheses with symptoms of prosthetic stomatitis (toxic and allergic stomatitis) demonstrated a significant effect on the bioelectric activity of the proper masseter muscles as compared with patients in group 1. The average amplitude of volitional compression was less at 2.8 times and the average amplitude of arbitrary chewing was less at 2.1 times, the dynamics of the states of rest and activity of chewing muscles was impaired. A reduction in the activity time and a slight increase in the resting time both on the working side and on the balancing side, as compared to patients in group 2 were observed in the first day after prosthetics with magnetron C60 fullerene nano-coating. Patients in group 3 demonstrated an increase in bioelectric activity (the amplitude of biopotentials increased), as compared with group 2, both in volitional compression and in arbitrary chewing. On the 15th day of observation, the electromyographic pattern in patients of group 3 changed and was characterized by a pronounced tendency to normalized indicators of the activity and rest time. The electromyogram amplitude of the masseter muscles increased significantly, but at this time the observations did not reach the values of group 1. One month after applying the dentures, electromyograms of patients demonstrated a more pronounced alternation of activity waves with periods of rest, the amplitude of biopotentials oscillation increases. One month after denture placement, the indicators of group 3 approached the data, obtained in patients of group 1. After conducting the electromyographic study within 3 months, we found that in group 3, the values of average amplitude of arbitrary chewing and the amplitude of volitional compression of the masseter muscles were 2 times higher than those of group 2. The time of activity and rest became more balanced and did not differ significantly from indicators in group 1.

Consumption of dentures fixing agents and their impact on the oral mucosa of the prosthetic bed

The clinical and sociological study was conducted involving 283 (130 men and 153 women) patients aged from 45 to 92 years. All patients had acrylic removable dentures on one or both jaws. If patients had complaints about insufficient fixation of the denture, they were recommended to use a prosthesis fixing cream for daily use. After 14 days, patients were examined again for the dynamics of complaints, as well as changes in the mucous membrane of the prosthetic bed. Regardless of gender and age group patients using partial and complete dentures rarely (in 4.3% of cases) used dentures fixing agents, although 40.8% had poor fixation and (or) stabilization of removable acrylic partial and full dentures, and in 51.9% of cases inflammatory changes of the mucous membrane of the prosthetic bed were detected. Correction of removable dentures, as well as daily use of a denture fixation cream, made it possible within two weeks to reduce by 72.5% of patients complaints about poor fixation and (or) stabilization of removable dentures, as well as to eliminate existing inflammatory changes in 86.4% of patients.

Клінічний стан тканин протезного ложа в пацієнтів, які користуються різними адгезивними засобами для покращення фіксації знімних протезів

Клінічний стан тканин протезного ложа в пацієнтів, які користуються різними адгезивними засобами для покращення фіксації знімних протезів

ОЦЕНКА СОСТАВА МИКРОБИОТЫ ПЕРИИМПЛАНТАТНОЙ БОРОЗДЫ В ПРОЦЕССЕ ОСТЕОИНТЕГРАЦИИ ДЕНТАЛЬНЫХ ИМПЛАНТОВ

Background. The necessity of studying the microbiota of the oral cavity, as one of the main causes of complications after the installation of dental implants, is considered. In the dynamics of osseointegration of dental implants (1-6-12 months), a study was made of the species and quality composition of the microbiota of peri-implant and gingival furrows.
 Objectives ― to study the composition of microbiota in the gingival sulcus of an adjacent healthy tooth and the peri-implant sulcus of the implant in the process of osseointegration of dental implants.
 Methods. A microbiological study of the composition of the microbiota of the studied biotopes — the peri-implant sulcus and gingival sulcus of an adjacent healthy tooth in the process of osseointegration of dental implants in 83 patients was carried out. The total number of bacteria was detected by real-time polymerase chain reaction.
 Results. 1 month after the installation of dental implants and fixation of the Treponema denticola gingival former in the samples from the gingival sulcus of the tooth was 16.03 %, and the number of Tannerella forsythensis was 5.52 % higher than in the samples from the peri-implant sulcus. After 6 months, the total bacterial mass in the peri-implant sulcus was 12.7 % less. The amounts of Prevotella intermedia, Treponema denticola, Tannerella forsythensis and Porphyromorans gingivalis in the peri-implant groove decreased by 2.9, 6.1, 5.2 and 11.6 %, respectively. After 12 months, a statistically significant decrease in Porphyromorans gingivalis was observed 2.7 times (p <0.01) and 2.6 times (p <0.01), respectively, in the peri-implant and gingival sulcus.
 Conclusions. In the process of osseointegration of dental implants, the total bacterial mass (p <0.01), Porphyromorans gingivalis (p <0.01) decreased dynamically, statistically significantly, the number of Tannerella forsythensis increased (p <0.05). Also dynamically, but slightly, a decrease in Candida albicans was observed. After 12 months, an accumulation of Prevotella intermediaries was observed at the implantation sites.

Solubility of dental core build-up materials in electric fields

Background/purposeOver 250 years has been researched over the consequences of oral galvanism. Previous studies have already examined the influence on dental fixation materials. The aim of this study was to investigate the electro-chemical solubility behavior of different dental core build-up materials in a pseudo-realistic galvanic experimental setup. Materials and methodsThe composite Admira (Voco, Cuxhaven, Germany) and two glass ionomer cements, Ketac Molar and Photac (3M-Espe, Seefeld, Germany), were examined. Test specimens were exposed to electric field strengths of 10–27 V/m in 0.9% saline solution. After 1, 2, 3, and 24 h, 2 ml of the electrolyte was removed for analysis. Aluminum and calcium were selected as parameters to measure the solubility of the products. Differences between the test samples and controls were ascertained using the two sample t-test. ResultsFor all of the test groups, Admira demonstrated minimal solubility compared to Ketac and Photac. However, after 24 h in an electric field of 27 V/m, Admira demonstrated the highest increase in solubility compared to the controls (3.47 vs control at 0.76 μmol/l). The second highest increase yielded the conventional glass ionomer cement Ketac (8.62 vs control at 5.28 μmol/l), and a minor increase in solubility showed the composite-based glass ionomer material Photac (38.73 vs control at 31.78 μmol/l) compared to the controls. ConclusionThis study demonstrated that galvanic processes increase the solubility of glass ionomer and composite. Therefore, the time of storage, electric field strength, and contact of the material with the electrodes significantly influenced their solubility.

УДОСКОНАЛЕНІ МЕТОДИКИ ВИГОТОВЛЕННЯ ЗНІМНИХ ПРОТЕЗІВ З ВИКОРИСТАННЯМ САМОТВЕРДІЮЧОГО ЕЛАСТИЧНОГО МАТЕРІАЛУ


 Запропонована удосконалена технологія виготовлення двошарових повних знімних пластинкових протезів з використанням самотвердіючих еластичних базисних матеріалів. Запропоновано методику виготовлення безкламерних часткових знімних пластинкових протезів з використанням самотвердіючих еластичних матеріалів при наявності поодиноких зубів і приведено її оцінку за результатами клінічних спостережень.

Порівняльна оцінка фізико-механічних властивостей стоматологічних цементів для постійної фіксації ортопедичних конструкцій

Порівняльна оцінка фізико-механічних властивостей стоматологічних цементів для постійної фіксації ортопедичних конструкцій

Hydration dependent mechanical performance of denture adhesive hydrogels

ObjectiveHydration in denture adhesives regulates the formation of complex morphologies and mechanical function. Multiscale experimental approaches are required to evaluate the impact of hydration on the inherent heterogeneity of denture adhesive-based hydrogels at different length scales and the impact of such phenomena on adhesion performance. MethodsThe morphology of hydrated denture adhesives was examined via cryo-scanning electron microscopy (cryo-SEM). The rheological and thermodynamic behaviour of bulk hydrated deture adhesives was examined by rheology and differential scanning Calorimetry (DSC). The microscopic mechanical properties of the denture adhesives were characterised by atomic force microscopy (AFM) and compared to the properties measured at the macroscopic scale. ResultsThe rheological and mechanical properties of commerically available denture adhesive hydrogels were found to be critically dependent on both the formulation of the adhesives and their hydration level. Clear progression of phase separation was observed in hydrated denture adhesives as hydration increased and changed the mechanical properties of the adhesives at multiple length scales. The adhesives displaying more heterogeneous structures, which were associated with the presence of hydrophobic and organic compounds in the formulation, exhibited more variable mechanical behaviour and weaker rheological properties, but stronger adhesive properties. SignificanceOur results are important in defining the relationships between hydrophilicity, hydration, mechanical and adhesive properties of denture adhesives, allowing the development of improved chemical formulations that control the fixation of dentures.

Numerical Evaluation of Biomechanical Stresses in Dental Bridges Supported by Dental Implants

The number of supporting dental implants is an important criterion for the surgical outcome of dental bridge fixation, which has considerable impact on biomechanical load transfer characteristics. Excessive stress at the bone–implant interface by masticatory loading may result in implant failure. The aim of this study was to evaluate the impact of the number of implants supporting the dental bridge on stress in neighboring tissues around the implants. Results of the study will provide useful information on appropriate surgical techniques for dental bridge fixation. In this study, osseointegrated smooth cylindrical dental implants of same diameter and length were numerically analyzed, using three-dimensional bone–implant models. The effect of the number of supporting implants on biomechanical stability of dental bridge was examined, using two, three and four supporting implants. All materials were assumed to be linearly elastic and isotropic. Masticatory load was applied in coron-apical direction on the external part of dental bridge. Finite Element (FE) analyses were run to solve for von Mises stress. Maximum von Mises stresses were located in the cervical line of cortical bone around dental implants. Peak von Mises stress values decreased with an increase in the number of implants that support the dental bridge. Results of this study demonstrate the importance of using the correct number of supporting implants to for dental bridge fixation.

Sclerostin and DKK1 Inhibition Preserves and Augments Alveolar Bone Volume and Architecture in Rats with Alveolar Bone Loss

Alveolar bone is a mechanosensitive tissue that provides structural support for teeth. Alveolar bone loss is common with aging, menopause, tooth loss, and periodontitis and can lead to additional tooth loss, reduced denture fixation, and challenges in placing dental implants. The current studies suggest that sclerostin and DKK1, which are established osteocyte-derived inhibitors of bone formation, contribute to alveolar bone loss associated with estrogen ablation and edentulism in rats. Estrogen-deficient ovariectomized rats showed significant mandibular bone loss that was reversed by systemic administration of sclerostin antibody (SAB) alone and in combination with DKK1 antibody (DAB). Osteocytes in the dentate and edentulous rat maxilla expressed Sost (sclerostin) and Dkk1 (DKK1) mRNA, and molar extraction appeared to acutely increase DKK1 expression. In a chronic rat maxillary molar extraction model, systemic SAB administration augmented the volume and height of atrophic alveolar ridges, effects that were enhanced by coadministering DAB. SAB and SAB+DAB also fully reversed bone loss that developed in the opposing mandible as a result of hypo-occlusion. In both treatment studies, alveolar bone augmentation with SAB or SAB+DAB was accompanied by increased bone mass in the postcranial skeleton. Jaw bone biomechanics showed that intact sclerostin-deficient mice exhibited stronger and denser mandibles as compared with wild-type controls. These studies show that sclerostin inhibition, with and without DKK1 coinhibition, augmented alveolar bone volume and architecture in rats with alveolar bone loss. These noninvasive approaches may have utility for the conservative augmentation of alveolar bone.

Clinical follow-up evaluation of Dalbo®-Rotex® retention elements in the private practice

The aim of this retrospective study was to investigate the clinical outcome of Dalbo®-Rotex® retention elements in a private practice. The majority of the retention elements was fixed with self-adhesive composite cement, and in almost 40% the exposed root surface was additionally covered with composite. The success rate of 96.3% after 24 months in a total of 50 included patients (response rate 48.5%) demonstrated that a simple and cost-effective fixation of removable dentures using prefabricated, chair-side inserted retention elements is feasible. Maintenance care comprised single or repeated replacement and activation of the female part in 12.3% and 39.4% of the cases, respectively. Fractures were rare, occurring in 3.4% of the cases and more likely in patients with parafunctional habits. Frequent oral hygiene correlated with probing depths up to 3 mm at the maxi- mum, while the risk of greater probing depths associated with less frequent oral hygiene increased by a factor of 2.4. Patients’ assessment of the parameters handling and wearing comfort, chewing ability and prosthesis retention was predominantly positive. Based on the findings of the study, covering of exposed dentin areas with composite resin and regular recall comprising professional cleaning, fluoride application and oral hygiene instruction are recommended.

Clinical follow-up evaluation of Dalbo®-Rotex® retention elements in the private practice

The aim of this retrospective study was to investigate the clinical outcome of Dalbo®-Rotex® retention elements in a private practice. The majority of the retention elements was fixed with self-adhesive composite cement, and in almost 40% the exposed root surface was additionally covered with composite. The success rate of 96.3% after 24 months in a total of 50 included patients (response rate 48.5%) demonstrated that a simple and cost-effective fixation of removable dentures using prefabricated, chair-side inserted retention elements is feasible. Maintenance care comprised single or repeated replacement and activation of the female part in 12.3% and 39.4% of the cases, respectively. Fractures were rare, occurring in 3.4% of the cases and more likely in patients with parafunctional habits. Frequent oral hygiene correlated with probing depths up to 3 mm at the maxi- mum, while the risk of greater probing depths associated with less frequent oral hygiene increased by a factor of 2.4. Patients’ assessment of the parameters handling and wearing comfort, chewing ability and prosthesis retention was predominantly positive. Based on the findings of the study, covering of exposed dentin areas with composite resin and regular recall comprising professional cleaning, fluoride application and oral hygiene instruction are recommended.