The effectiveness of chemical denture cleansers and ultrasonic device in biofilm removal from complete dentures

Adequate denture hygiene can prevent and treat infection in edentulous patients. They are usually elderly and have difficulty for brushing their teeth.

Objective

This study evaluated the efficacy of complete denture biofilm removal using chemical (alkaline peroxide-effervescent tablets), mechanical (ultrasonic) and combined (association of the effervescent and ultrasonic) methods.

Material and Methods

Eighty complete denture wearers participated in the experiment for 21 days. They were distributed into 4 groups (n=20): (1) Brushing with water (Control); (2) Effervescent tablets (Corega Tabs); (3) Ultrasonic device (Ultrasonic Cleaner, model 2840 D); (4) Association of effervescent tablets and ultrasonic device. All groups brushed their dentures with a specific brush (Bitufo) and water, 3 times a day, before applying their treatments. Denture biofilm was collected at baseline and after 21 days. To quantify the biofilm, the internal surfaces of the maxillary complete dentures were stained and photographed at 45º. The photographs were processed and the areas (total internal surface stained with biofilm) quantified (Image Tool 2.02). The percentage of the biofilm was calculated by the ratio between the biofilm area multiplied by 100 and the total area of the internal surface of the maxillary complete denture.

Results

The Kruskal-Wallis test was used for comparison among groups followed by the Dunn multiple-comparison test. All tests were performed respecting a significance level of 0.05. Significant difference was found among the treatments (KW=21.18; P<0.001), the mean ranks for the treatments and results for Dunn multiple comparison test were: Control (60.9); Chemical (37.2); Mechanical (35.2) and Combined (29.1).

Conclusion

The experimental methods were equally effective regarding the ability to remove biofilm and were superior to the control method (brushing with water). Immersion in alkaline peroxide and ultrasonic vibration can be used as auxiliary agents for cleaning complete dentures.     

In vitro study on the effects of trial denture cleansers with berberine hydrochloride

The antifungal activity of trial denture cleansers prepared with berberine hydrochloride was examined against Candida albicans, C. tropicalis, and C. glabrata. A commercial denture cleanser and a trial denture cleanser that exhibited strong antifungal activity were tested for their effects on Candida spp., the color stability of the dental material, and the surface roughness of acrylic resin plates. The results of these tests revealed that the trial denture cleanser removed 64% to 89% of adhered cells from acrylic resin surfaces and had little effect on the other physical properties tested.     

Dimensions of metal framework components of metal-ceramic fixed partial dentures constructed in a dental school setting.

OBJECTIVES: The aims of this study were to measure the dimensions of connectors and retainer copings of metal-ceramic fixed partial denture (FPD) frameworks and to explore, by means of a questionnaire, the factors viewed by technicians as important in their planning and provision of such dimensions. METHOD AND MATERIALS: Using two calliper devices, measurements were made of 66 consecutive FPDs under production in a dental school-based laboratory. The dimensions of 176 connectors and 124 retainers were analyzed with reference to FPD length and to number of pontics in a span. Questionnaires were completed by all 14 technicians working in the fixed prosthodontics section of the laboratory. RESULTS: The largest mean vertical connector dimensions were in the anterior regions of both arches, while the largest mean horizontal dimensions were in the posterior regions. Dimensions were unrelated to FPD size and length of interabutment span. The minimum thickness of the retainer coping walls was generally below optimal recommendations. Available space was the factor most commonly cited by technicians as dictating the dimensions that they applied. CONCLUSION: Dimensions were generally smaller than current recommendations, which the questionnaire responses indicate are largely due to space constraints.     

The prevention of allergy to metal dentures

Investigation of 124 patients visiting the clinic for incompatibility with metal dentures revealed the risk factors for allergic response in the oral cavity. Reliable and easily applied techniques were developed to diagnose allergic responses in an outpatient dentistry units which allowed to preselect the optimal alloy to manufacture dentures for each individual patient. Clinical signs of allergy to several metals were clarified.     

弹性义齿与传统可摘局部义齿对牙周情况影响的比较

目的比较弹性义齿与传统可摘局部义齿对牙周组织健康的影响。方法选择12例牙列缺损病人。每例受试者同时制作一件铸造卡环活动桥修复体和一件弹性义齿。先后戴用两种义齿，对基牙临床检查和龈下茵斑检查。结果戴用铸造卡环活动桥后PLI高于戴用弹性义齿后。戴用弹性义齿后BI及龈下菌宽螺旋体比例略高于戴用铸造卡环活动桥后。其他指标两者无差别。结论弹性义齿卡环设计时应尽量减少覆盖牙龈的面积，避免卡环边缘终止于龈缘处。     

Repairs of metal parts of removable partial dentures

The clinical and laboratory phases of repairing broken clasps and major connectors have been described. These techniques offer clinically acceptable results and are a necessary part of removable partial denture service and maintenance.     

Adaptation of acrylic dentures reinforced with metal wire

The aim of this study was to reveal the effect of metal wire on the adaptation of the denture reinforced with it. Forty maxillary dentures were made with two polymerization systems (DS system and SR-Ivocap system). The dentures were divided into two groups: (1) the unreinforced dentures (control) and (2) the dentures reinforced with metal wire 1.0 mm in diameter. Discrepancies between the denture base and the stone cast were measured at five points immediately after polymerization and after a 30-day immersion in water. The data were analysed using a two-way or one-way ANOVA test. Dentures reinforced with metal wire exhibited significantly lower adaptation to the stone cast than the unreinforced ones for each polymerization system. Immersion in water did not affect the adaptation of dentures reinforced with metal wire for each polymerization. Unreinforced dentures made by the DS system had significantly smaller discrepancies compared with the dentures processed with the SR-Ivocap system. The adaptation of the dentures reinforced with metal wire decreased in comparison with the unreinforced ones regardless of the polymerization method. This should be considered when metal wire is used clinically as reinforcement.     

Composite veneering of metal based fixed partial dentures

The aim of this in vitro study was to determine the thermal mechanical properties of veneering composites after polymerization with the appropriate polymerization device. Fracture tests were performed to investigate the effect on fixed partial dentures (FPDs). Dynamic mechanical thermal analysis was used to determine the temperature-dependent mechanical properties. To approximate the clinical situation, the fracture resistance of three-unit metal-based FPDs with different composite veneering was investigated after a simulated 5-year oral wearing period. The restorations were made of a high gold alloy and veneered with three different composites. To determine the influence of fabrication, one composite was used in a light-polymerizing and a heat/pressure-curing version and, in addition, a newly developed heat protection paste was used. After a 5-year simulation period, the fracture resistance was determined. The storage modulus varied between 14268 N mm(-2) (Belleglass) and 6616 N mm(-2) (Sinfony). Adoro showed no significant differences between light curing (9155 N mm(-2)) and heat curing (8184 N mm(-2)) variations. The Adoro-veneering with the heat protection paste showed the highest median fracture strength (1700 N), followed by Adoro LC (1555 N), Belleglass (1051 N), Adoro HP (1150 N) and Sinfony (909 N). The most common failure type occurring in all FPDs was a cracking of the composite, exposing the metal framework. All FPDs showed stress cracking of the composite. The heat protection paste seemed to reduce the crack formation after fabrication and increased the fracture resistance of the composite veneering. Stress cracking after thermal cycling and mechanical loading affected all composites, but all veneered three-unit alloy FPDs showed a fracture resistance sufficient for posterior application.     

Copper vapour laser ID labelling on metal dentures and restorations

Denture marking is accepted as a means of identifying dentures and persons in geriatric institutions, or post-mortem during war, crimes, civil unrest, natural and mass disasters. Labelling on the acrylic resin component of the denture can easily be damaged or destroyed by fire but on cobalt-chromium components it would be more resistant. A copper vapour laser (CVL) can be used to label the cobalt-chromium components of dentures and metal restorations easily, and legibly, and miniaturised for the incorporation of more personal particulars necessary for the identification of the deceased person. The CVL beam is focussed by its optics and delivered to the material surface by the two-axis scanner mounted with mirrors. A personal computer controls the movement of the scanner and the firing of the CVL. The high peak power of the pulsed CVL is focussed to very high energy density producing plasma ablation of the alloy surface. Very fine markings of a few microns width can be produced enabling the storage of detailed information of the deceased person on a metal surface for the purpose of rapid identification.     

The prevention of complications in the use of metal ceramic dentures

The methods of prevention of complications of metalloceramic prostheses are described. A compound is designed for temporary fixation of nonremovable dentures which allowed the 2-months follow-up of the patients and did not prevent corrections at any stage of treatment. Outpatient follow-up is necessary in the cases of metalloceramic prosthesis application.     

The effect of some components on the rigidity of mandibular bilateral free end saddle dentures

One partially dentate person, his remaining teeth being 44, 43, 42, 41, 31, 32 and 33, was simultaneously provided with one maxillary complete denture and three mandibular free end saddle dentures having cobalt chromium alloy skeletons of different design. One denture was constructed with a lingual plate, another with a sublingual and a secondary bar, while on a third denture the major connector consisted of an enlarged secondary bar. On all the dentures occlusal rests were placed on teeth nos 44 and 33. Rosette strain gauges were placed in the midlines of all the major connectors. The gauges were calibrated on the master cast placed in a universal testing machine. The clinical recordings were taken from the gauges during one session under repeated loading conditions. Readings were repeated on one denture after removal of (1) the secondary bar and (2) the secondary bar and the occlusal rests. The recordings were used to calculate (I) the principal maximum and minimum strains and (2) the direction of the strains at the points of the bases beneath the centre of the gauges. The results show that studies of relevant functional deformation patterns of dentures can only be made in clinical experiments. Further, they show that the base with an enlarged secondary bar exhibits more deformation than the other two types of base. Removal of the secondary bar did not significantly increase the deformation of the denture also equipped with a sublingual bar, neither did the removal of the occlusal rests. Both these changes, however, caused changes of the deformation patterns.     

The effect of metal dentures in the oral cavity on the electric conductivity of the saliva

Salivary electric conductivity depends on ion concentration and mobility, on electrochemical and chemical processes related to the presence of dentures made of various alloys in the oral cavity. Therefore, salivary electric conductivity is a significant quantitative characteristic of the processes in the buccal mucosa.     

Comparative study of maxillary complete dentures constructed of metal base and metal structure framework

A removable denture designed using a three-dimensional cast metal framework (hereafter referred to as the 'structurally designed' denture) could extend denture longevity because it is unbreakable and easy to adjust. The aim of the present clinical study was to compare two types of maxillary removable dentures: conventional dentures and structurally designed denture. One edentulous and five partially dentate patients were fitted with two maxillary dentures made from the same impression and same occlusal relationship. About 20 days after delivery of the denture, masticatory analysis was conducted chewing phase (open, closed, and occluded); coefficients of variation and average variation were calculated. Denture vibration during tapping was then measured using an accelerometer. The patients were also interviewed about comfort, ease of chewing, speech, stability, aesthetics and preference for regular use. For both masticatory movements and denture vibration, there were no significant differences (P>0.1) between the conventional denture and the structural design denture. In evaluating the dentures according to each criteria, the significant superiority of one denture over the other could not be determined. However, all patients subjectively preferred the structurally designed dentures for regular use. According to these findings, structurally designed dentures do not appear to have any particular physiological problems as compared with the conventional dentures.