Clinical assessment of implant-supported full-arch immediate prostheses over 6 months of function.

OBJECTIVE: To assess the clinical outcomes of implant-supported full-arch immediate prosthesis over 6 months of functions and analyze the risk factors of prosthetic complications. MATERIALS AND METHODS: This retrospective cohort study included patients who were treated with implant-supported full-arch restoration under immediate loading protocol between April 2008 and June 2016, and who wore the immediate prosthesis for more than 6 months. Medical charts were reviewed for the patients' general information, implant information, prosthetic information, and details of any prosthetic complications. Prosthetic complications were classified as follows: class I, prosthesis loosening; class II, fewer than three artificial teeth fractured; class III, three or more artificial teeth fractured; and class IV, resin base fractures. A cox proportional hazards ratio model was adopted to analyze the potential risk factors for class IV complications. RESULTS: A total of 114 patients (mean age, 56.73 ± 10.19 years) and 144 prostheses were included. The average wearing time for the immediate prosthesis was 21.9 months, and 62 (54.39%) patients experienced prosthetic complications, 30 of whom suffered from complications more than once. The most common complications were class II complications (12.3%) during the first 6 months of functioning and class IV complications (28.1%) during the entire function period. Class II complications were more common in the anterior region, while class IV complications occurred more often in the posterior region. The multivariable Cox proportional hazards regression model showed that a prosthesis in the maxilla (HR = 3.37, P = .001) and fiber reinforcement (HR = 0.39, P = .021) were significantly related to class IV complications. CONCLUSIONS: Implant-supported full-arch immediate prosthesis functioning over 6 months have a high prevalence of prosthetic complications. Fiber-reinforcement could reduce the prevalence of class IV complications when acrylic immediate prosthesis functioned longer than 6 months. Avoiding using the anterior teeth of the immediate prosthesis to tear pliable but strong food may prevent tooth fracture.

In Vitro Assessment of the Abrasion Resistance of Two Types of Artificial Teeth Submitted to Brushing.

PURPOSE: To assess the effect of brushing with different solutions on the abrasion resistance of two types of acrylic resin teeth. MATERIALS AND METHODS: Maxillary premolars from two types of acrylic teeth (Biotone and Biotone IPN) were divided into six groups (n = 12), according to the solution used during brushing: distilled water (control), coconut soap, or dentifrice. A mechanical brushing machine was used to simulate approximately 1 year of brushing (11,000 strokes). The weight loss (WL) of teeth was obtained from the difference between the initial (IW) and final weight (FW) of each specimen, and the mean of percentage of weight loss (PWL) was calculated for each group. Data were analyzed using the Kruskal-Wallis test, followed by Bonferroni's post-test comparison (α = 0.05). RESULTS: A statistically significant difference was found for the factor solution (p < 0.001). Brushing using dentifrice caused the highest values of weight loss (-0.50%), in comparison with the groups brushed with coconut soap (0.00%) or distilled water (0.00%). CONCLUSIONS: For both types of artificial teeth, brushing with dentifrice produced higher abrasion than brushing with coconut soap or water.

Assessment of Artificial Teeth Setup Device: A Three-Dimensional Model Analysis.

This study assessed the use of the commercial artificial teeth setup device Staub Cranial System (Neu-Ulm) in Asian subjects. Fourteen completely dentate Thai volunteers were randomly recruited. Study casts (control group) and duplicated casts (experimental group) of all subjects were prepared. Artificial teeth were replaced on duplicated casts according to the manual. Computed tomography scans of all casts were performed. Intercanine width, intermolar width, incisocervical length, and occlusal plane were investigated. The length of the natural mandibular left central incisor was smaller than the reconstructed one. The reconstructed occlusal plane was more parallel to the hamular-incisive papilla plane than that of the control group.

Employment of Reservoirs in At-Home Whitening Trays: Efficacy and Efficiency in Tooth Whitening.

AIM: This study aimed to determine the efficacy of trays made with and without reservoirs, in conjunction with time and cost evaluations, by measuring color change with home whitening procedures. MATERIALS AND METHODS: Extracted human maxillary teeth (central incisors n = 20; canines n = 20; molars n = 20) and 60 artificial teeth (lateral n = 20; premolar n = 40) were mounted into ten typodonts. Tray fabrication was completed such that a block-out resin reservoir was placed on half of the buccal surface of the tray, while the other half remained without a reservoir. Whitening with custom fabricated trays was performed based on two different whitening regimens, where each regimen was assigned to five typodonts: Night-time: Opalescence PF 10% carbamide peroxide for 8 hours daily and Day-time: Philips DayWhite 9.5% hydrogen peroxide for 30 minutes, twice daily. Both systems were applied for 1 week. To evaluate tooth shade, the VITA Easyshade® Advance 4.0 spectrophotometer was used. Color measurements were obtained at baseline (T1), 1-day post-whitening (T2), and 1 month post-whitening (T3). One-way ANOVA, followed by post-hoc Tukey's HSD test, was used to detect significant difference in the overall color change (ΔE*) among the four groups at T2 and T3. Additionally, paired-sample t-test was used to assess difference in ΔE* between T2 and T3 treatment within each of four techniques of tray fabrication. RESULTS: No significant difference in ΔE* was found among the four groups at T2 and T3 (p > 0.05 in each instance). There were significant differences in mean ΔE* between T2 and T3 treatment for the day white treatment groups without reservoir (6.96 vs 10.19 respectively; p = 0.0026) and with reservoirs (6.23 vs 9.79 respectively; p = 0.0031). CONCLUSION: The use of reservoirs does not have a significant effect on whitening efficacy, regardless of type of whitening material and regimen. CLINICAL SIGNIFICANCE: The use of custom fabricated trays with or without reservoirs were equally effective in whitening teeth.

Digital data acquisition for a CAD/CAM-fabricated titanium framework and zirconium oxide restorations for an implant-supported fixed complete dental prosthesis.

This dental technique report describes a digital workflow with digital data acquisition at the implant level, computer-aided design and computer-aided manufacturing fabricated, tissue-colored, anodized titanium framework, individually luted zirconium oxide restorations, and autopolymerizing injection-molded acrylic resin to fabricate an implant-supported, metal-ceramic-resin fixed complete dental prosthesis in an edentulous mandible. The 1-step computer-aided design and computer-aided manufacturing fabrication of titanium framework and zirconium oxide restorations can provide a cost-effective alternative to the conventional metal-resin fixed complete dental prosthesis.

Occlusal support including that from artificial teeth as an indicator for health promotion among community-dwelling elderly in Japan.

AIM: The Eichner index (EI) is used to evaluate occlusal support. However, this index is based on existing natural tooth contact. This study aimed to establish whether a modified EI that included artificial teeth reflected individual oral condition of elderly people, and to clarify the relationship between this index and: (i) mental condition; (ii) physical condition; and (iii) physical function. METHODS: We recruited 286 people (145 men, 141 women) aged 65-79 years. They were divided into three groups by modified EI, and then underwent assessment of oral condition. After establishing that the index was clearly related to oral condition, we investigated psychological factors (satisfaction with life, self-rated health and anxiety regarding falling), indicators of walking and balance (Timed Up & Go test [TUG] and one-leg standing balance), physical condition (higher-level functional capacity [HLFC]: instrumental activities of daily living [IADL], intellectual activity and social role; continuous walking over 15 min; and frequency of outings), and health history in the previous year (history of hospital admissions and falls). RESULTS: Modified EI was a good indicator of occlusal condition. The index was significantly correlated in men with satisfaction with life, TUG test, one-leg standing balance, overall HLFC and HLFC-IADL, and in women with TUG test, one-leg standing balance and HLFC-Intellectual activity. CONCLUSION: The evaluation of occlusal support including that from artificial teeth is beneficial in the elderly as an indicator of health and oral function, in particular firm bite.

Intraoral framework pick-up technique to improve fit of a metal-resin implant prosthesis.

The achievement of passive fit is an important prerequisite for the prevention of complications in full-arch screw-retained implant prosthesis. With cemented prosthesis, the cementation compensates for the discrepancies in the cast framework, but the lack of retrievability seems undesirable. The aim of this paper is to propose a modified screw-retained prosthesis design for complete arch implant fixed rehabilitation. A technique for the fabrication of a full-arch metal-resin implant-supported screw-retained prosthesis is described. Cementation of the framework to the abutments intraorally improves the passivity of fit of the prosthesis on the implants. Maintenance of screw-access channels in the final prosthesis ensures retrievability. The metal-resin design allows for easy repair and maintenance. The prosthesis is cost-effective compared to conventional options and can be employed as a viable treatment alternative when considering metal-acrylic resin complete arch fixed prosthesis.

Assessment of perceptibility and acceptability of color difference of denture teeth.

OBJECTIVES: To assess the color difference values that represent the perceptibility and acceptability thresholds of denture teeth. METHODS: Eighteen interchangeable right upper central incisors denture teeth were selected to have color difference values from representative left upper central incisor denture tooth in a range of 0.4-11.4 ΔE* units measured with a spectrophotometer (CM 2600d, Minolta Konica, Japan). These teeth were placed in an artificial dental arch in a phantom head. Under controlled conditions, a total of 80 observers divided into 4 groups (technicians, nurses, dentists and researchers) were asked to report the perceptibility and acceptability of each of the color difference values. The findings was then analysed using logistic regression for determining the perceptible and acceptable thresholds of dental color differences. RESULTS: The determined color difference values at which 50% of all observers could detect a color difference (50:50 probability) was 1.9 ΔE* units with a 95% confidence interval and ranged from 1.7 ΔE* units to 2.1 ΔE* units. The determined color difference value at which 50% of all observes preferred to replace the tooth because of unacceptable color difference (50:50 probability) was 4.2 with a 95% confidence interval that ranged from 3.9 ΔE* units to 4.7 ΔE* units. CONCLUSIONS: Within the limitation of this study, the following conclusions were made: 1. The mean color perceptibility threshold was significantly lower than the mean color acceptability threshold. 2. Significant differences between different observers groups were noticed in determination of perceptibility and acceptability of color differences. The technicians groups displayed lower perceptibility and acceptability limits than the dental nurses and non-dental observers. CLINICAL SIGNIFICANCE: When shade matching artificial denture teeth to natural teeth, 50:50 perceptibility (1.9 ΔE* units) and acceptability (4.2 ΔE* units) thresholds are used to compare color difference values. The technicians group displayed lower perceptibility and acceptability limits than other observers.

Risk management in clinical practice. Part 6a. Identifying and avoiding medico-legal risks in complete denture prosthetics.

The provision of complete dentures is often perceived as a clinical 'black art' as it relies on a blend of clinical skill, scientific evidence and no little artistic interpretation. Coupled to this is a heavy reliance on patient ability to control their dentures in a muscular environment while, hopefully, coping with the various oral functions in addition to appearance. This article deals with the potential problem areas in the provision of complete dentures, reinforcing the importance of practitioners obtaining appropriate informed consent and of maintaining clinical knowledge and skills.

Evaluation of in vivo denture plaque assessment methods.

BACKGROUND: Measurement and assessment of denture plaque can provide valuable information regarding an individual's oral health status and assessment of new treatments or products. Current methods tend to rely on subjective indices or image analysis derived planimetric (area measurement) assessment of stained plaque on dentures. Plaque indices are most commonly used to assess plaque coverage without image capture. This is not ideal because the methods are subjective, examiner bias may occur, there is no reproducibility between studies, the methods have lower accuracy and sensitivity than image analysis, and there is no record. To the authors' knowledge, no standardised published method of denture plaque assessment is currently employed for product development and testing. METHOD: In this study visual and planimetric plaque assessment methods were compared using reference dentures. In addition, an in vivo study compared these methods for evaluating denture cleanser efficacy. RESULTS AND CONCLUSIONS: The results show that blinded image scoring is more representative of the true plaque area coverage than 'live' denture scoring, detecting significant decreases in plaque coverage. Planimetric analysis provides a more sensitive and less subjective technique with greater differentiation between treatments. However, analysis is very time consuming. Thus, a number of recommendations are made regarding quantification of denture plaque for the assessment of cleanser products.

Cone-beam computed tomography in assessment of periodontal ligament space: in vitro study on artificial tooth model.

The aim of this in vitro study was to compare cone-beam computed tomography (CBCT) to conventional radiography (RG) in the assessment of the periodontal ligament space. A phantom with a variable "artificial" periodontal ligament space (0, 100, 200, 300, and 400 microm) was used as a model. The examinations were performed simultaneously with RG and NewTom 9000 digital volume tomograph. Assorted after increasing widths, 15 RGs and 15 CBCT images were presented for judgment to 20 dentists (DD), 20 dental assistants, and 20 dental students. Several weeks later, the same images were randomly mixed and presented to the same 20 DD again. The trial shows that RG gaps wider than 200 microm could be correctly identified by all participants with an accuracy of nearly 100%. A significant difference was observed between the modalities (p<0.05 and p<0.001) where conventional RGs performed better than CBCT for assessment of periodontal ligament space. Interobserver variation in relation to each technique was evaluated and no significant difference was found (p>0.05). In subjective evaluations of image quality with CBCT, the results were basically inferior for images of artificial periodontal ligament space, regardless of the experience of the observers.

Avaliação da exposição dentária, altura labial e paralelismo incisal, em diferentes faixas etárias / Assessment of dental exposure, lip height and incisal parallelism, in several classes of age

No presente estudo avaliou-se a exposição dentária, a altura labial e o paralelismo incisal, em 120 indivíduos de ambos os sexos, com idades de 20-30, 31-40, e acima de 41 anos. Os resultados mostraram que com o aumento da idade há uma redução gradual da exposição incisal superior, com o lábio em repouso, sendo esta estatisticamente significativa. Os demais resultados apresentaram valores médios semelhantes. O paralelismo incisal e a altura labial média estavam presentes em maior porcentagem. A exposição incisal inferior, durante o sorriso, foi de 2 a 3,5 mm e a superior, acima de 4 mm

In vitro wear assessment of titanium alloy teeth.

PURPOSE: Wear of commercially pure (CP) titanium prosthetic teeth has frequently been observed. The greatest wear has been found when the same grades of CP titanium are used for both maxillary and mandibular teeth. This study examined the wear behavior of teeth made with cast titanium alloy and compared these results with those for CP titanium and gold alloy teeth. MATERIALS AND METHODS: All tooth specimens were cast with grade 3 alpha titanium, 3 metastable beta alloys [Ti-15Mo-2.8Nb-0.2Si (Timetal 21 SRx), Ti-13Nb-13Zr, and Ti-15V-3Cr-3Sn-3Al], and 2 alpha+beta alloys (Ti-6Al-7Nb and Ti-6Al-4V). As a control, Type IV gold alloy was also cast conventionally. All teeth (both maxillary and mandibular) were secured in an in vitro 2-body wear testing apparatus that simulated chewing function (60 strokes/min; grinding distance, 2 mm under flowing water). Wear resistance was assessed as volume loss (mm(3)) at 5 kgf (grinding force) after 50,000 strokes. The results (n = 5) were analyzed using analysis of variance or Fisher's exact test (alpha = 0.05). RESULTS: Of the titanium teeth, the wear of 2 of the metastable beta alloys (Timetal 21 SRx and Ti-15V-3Cr-3Sn-3Al) was found to be significantly (p <0.05) higher than that of CP titanium and the 2 alpha+beta alloys. The Type IV gold alloy exhibited better wear resistance than all of the titanium teeth tested. No correlation was found between wear loss and hardness among all the metals tested. CONCLUSIONS: Among the titanium teeth examined, the alpha+beta alloys exhibited significantly less wear than the other types of titanium. The dental casting gold alloy tested exhibited the best wear resistance among all of the metals tested.

Frequency and costs of technical failures of clasp- and double crown-retained removable partial dentures.

OBJECTIVES: The aim of this study was to evaluate the frequency of technical failure rates and the maintenance costs of clasp- or double crown-retained removable partial dentures (RPDs) (parallel-sided and conical double crowns). MATERIAL AND METHODS: According to three different retainer systems used between January 1992 to December 1998, three subgroups were randomly assigned from a group of 181 patients consisting of forty cases each. The average observation time was 4.2+/-1.7 years, with a minimum of 1.0 years and a maximum of 6.9 years. Technical complications such as fractures of the artificial teeth, loss of cementation, loss of facings as well as fractures of the metal framework and the soldering were recorded due to the medical reports. RESULTS: Twenty percent of all clasp-retained dentures showed technical complications during the observation period, whereas 50% of conical crown-retained (CC) and 32.5% of the parallel-sided retained dentures (PS) required repair. Most often reported was loss of cementation for double crowns (n=13, 32.5% PS; n=8, 20% CC) and fractures of the clasps (n=5). Although clasp-retained dentures had a markedly lower frequency of failures (n=8) than double crown systems (n=31), the calculated repair costs per event during the observation time were more than twice as high for clasp-retained dentures (172.5 Euro) than for double crown systems (8-78 Euro). The hypothesis that the maintenance costs of the more sophisticated double crown system are higher must be rejected.

[Lingualized occlusion in the South African context]. / Gelingualiseerde okklusie in die Suid-Afrikaanse konteks.

The search for the ideal artificial tooth arrangement that maximizes denture stability, comfort, aesthetics, and function has occupied the dental literature for many years and still continues to do so. Of the many occlusal schemes that have been presented to the dental profession, that of lingualized occlusion has emerged as one of the more popular. The popularity of lingualized occlusion stems from the simplicity and flexibility of the concept and from its wide application to clinical practice (Parr & Ivanhoe, 1996). The registration of a repeatable correct centric jaw relation is not always possible. We don't know whether the patient will use centric relation during normal function. It is therefore useful to provide the patient with some freedom of movement around centric. lingualized occlusion provides freedom in centric. For many dentists the arrangement of artificial denture teeth into balanced occlusion is difficult and time consuming. As a result this task is most often performed by the dental technician. In the South African countryside dental laboratories are often far away. If dentists perform the arrangement of the denture teeth, time and costs can be saved. The mounting of denture teeth in lingualized occlusion is simple and fast. This will motivate dentists to arrange denture teeth themselves, with obvious benefits for both the patient and the dentist. The School of Oral Health Sciences of the University of Stellenbosch teaches this concept to its undergraduate students in order to improve the prosthetic service to the large edentulous population of South Africa.

Onlay partial denture technique for assessment of adequate occlusal vertical dimension: a clinical report.

Clinical treatments that require restoration of occlusal vertical dimension pose a challenge to prosthodontists. This article describes the modification of existing removable partial dentures into onlay interim prostheses. This process allowed the patient's tolerance to the restored occlusal vertical dimension, esthetics, and phonetics to be evaluated before irreversible changes were made to the dentition.

An assessment of the ability of dental undergraduates to choose artificial teeth which are appropriate for the age and sex of the denture wearer: a pilot study.

One of the main objectives in selecting and arranging artificial teeth is to produce prostheses which defy detection. With an appropriate degree of clinical experience and expertise it should be a relatively straightforward procedure to select a suitable artificial tooth mould. However, for the relatively inexperienced dental undergraduate it can be a challenging process. The aim of this study was to assess the ability of dental undergraduates to select artificial teeth which are appropriate for the age and sex of the denture wearer. One hundred and fifty dental undergraduates aged 18-35 were asked to complete a questionnaire to assess their attitudes towards artificial tooth selection and asked to correctly identify six artificial tooth arrangements according to age and sex. The results showed that a large percentage of dental undergraduates at Bristol experience difficulty in selecting artificial teeth which are appropriate for the age and sex of the denture wearer. There is a need for improved training and guidance on artificial tooth selection and arrangement.

A longitudinal clinical assessment of spark erosion technology in implant-retained overdenture prostheses: a preliminary report.

STATEMENT OF PROBLEM: As adapted for the dental profession, spark erosion technology permits precise machining of retentive metal overdenture frameworks for use in implant prosthetics. PURPOSE: The resultant prostheses are retentive and provide a number of benefits offered by both conventional overdenture and fixed prosthetic designs. MATERIAL AND METHODS: Preliminary data collected from an ongoing 5-year clinical trial were reviewed to qualitatively assess the clinical results obtained from 25 spark eroded implant-retained overdenture prostheses placed in 24 subjects. RESULTS: Throughout an evaluation period of 13.33 months (range 4 to 19 months), subject responses measured by questionnaire were uniformly good. Few complications were encountered and were limited to resin denture base/tooth fractures or retentive component failures that were easily repaired. CONCLUSION: Overdenture prostheses retained by spark eroded milled frameworks offer an acceptable treatment alternative for patients undergoing dental implant therapy.