Cross Arch Research Articles

Four Digital Intraoral Scanners versus Conventional Impression Technique: An In-Vitro Evaluation of Fit Accuracy on Multiunit Abutments for Cross Arch Implant Restorations

Four Digital Intraoral Scanners versus Conventional Impression Technique: An In-Vitro Evaluation of Fit Accuracy on Multiunit Abutments for Cross Arch Implant Restorations

Comparison of Dimensional Stability of Alginate Impressions by Spraying 0.5% Sodium Hypochlorite Against Kepok Banana Peel Extract (Musa paradisiaca Linn.)

Background: The process of impressions of hard and soft tissues in the oral cavity is a fairly routine activity in dentistry. Alginate is an irreversible elastic impression material that is often used. Alginate can be disinfected using soaking or spraying techniques. This disinfection solution itself has side effects that are quite serious for patient health. This study aimed to find out Comparison of the dimensional stability of alginate impressions by spraying 0.5% sodium hypochlorite against kepok banana peel extract (Musa paradisiaca Linn.).
 Methods: This study was experimental research. The research object used was dimension of alginate impressions which were grouped into control and treatment groups. Assessment of the projection value of the antero-posterior (AP) and cross arch (CA) lines was carried out with digital calipers. Data analysis was carried out with the help of SPSS version 25 in univariate and bivariate.
 Results: The results of this study showed that the mean value of the AP and CA lines in the kepok banana peel extract treatment group did not show a significant difference with the control treatment (sodium hypochlorite 0.5%), p-value> 0.05.
 Conclusion: Spraying kepok banana peel extract with various concentrations did not cause changes in the dimensions of the alginate impressions.

Prosthetic management of mandibulectomy patient: A case report

Maxillofacial defects hampers function, form and esthetics. Cantor and Curtis classified the mandibulectomy defects. This is a case of prosthetic rehabilitation of Class 1 radical mandibulectomy where continuity of mandible was preserved. The patient has been rehabilitated with a definitive treatment of cast partial denture which provides better cross arch stabilization and does not subject already debilitated patient to more of surgeries.

Rehabilitation Of A Partially Dentatepatient With A Maxillary Cast Partial Denture And Mandibular Overdenture - A Case Report

Using natural teeth as denture abutments can significantly slow the progression of residual ridge resorption.The abutments and the denture bearing areas can share the stress concentration. Overdentures can help reduce residual ridge resorption by providing sensory feedback, occlusal stability loss, aesthetics loss, and compromised mastication. Overdenture has been shown to be effective in reducing residual ridge resorption and increasing retention and stability. When edentulous areas are too large or numerous for fixed prosthesis and cross arch stabilisation is required, a cast partial denture is preferred. Insertion and removal of the denture, as well as regular oral hygiene, are simple procedures. The current case-report describes the rehabilitation of a partially dentate mouth using a maxillary castpartial denture and mandibular overdenture.

Alginate Substitute as a Promising Impression Material for Dental Implant Restorations: A Comparative In-vitro Study

Objective: To compare the accuracy of alginate substitute with polyvinyl siloxane (PVS) impression materials for both single and multiple implant restorations using open- and closed-tray techniques placed unilaterally in a partially edentulous maxillary Typodont model. Methods: Two maxillary typodont hard models, two impression materials and two impression techniques were used in this study. A total of 80 impressions were made for both models simulating clinical scenario for single and multiple implant restorations, 10 impressions for each subgroup. Accuracy was assessed by measuring three dimensions (Anteroposterior, cross arch and vertical) on stone models obtained from impressions of the typodont models. Each dimension was measured three times and the mean value was calculated. The data were analyzed using independent samples t-test and Mann- Whitney U Test. Results: In group 1 (single implant), significant differences were found only in the vertical dimension between alginate substitute and monophase PVS impression materials when using an open-tray technique (mean diff.= 0.17; P= 0.003), and between closed- and open-tray techniques when using alginate substitute impression material (mean diff.= -0.24; P= 0.008). In group 2 (multiple implants), significant differences were found only in the horizontal cross-arch and vertical dimensions between open and closed-tray techniques when using alginate substitute impression material (P= 0.049 and P≤ 0.01, respectively). Conclusion: The results obtained showed that the stone dies fabricated using monophase PVS and alginate substitute impression materials were comparable to those of the typodont models. Overall discrepancies of the monophase PVS were smaller than those of the alginate substitute but not statistically significant.

A methodology for determining precision and accuracy of the measurement of position and orientation of implant interfaces for multi-implant structures.

The digital workflow relies on many technologies such as intra-oral scanners, CBCT, guided surgery, robotics, and photogrammetry. Efficient and uniform testing methods are required for assessing the precision and accuracy of these systems to select the right technology for the right task. The method uses values that are directly derived from the measurement of the implant position and orientation in the scanning software, photogrammetry software, and/or the CAD software. It was developed over a decade ago for desktop scanners and successfully used for photogrammetry, intra-oral scanners, and CBCT. The components which can be evaluated are the positional precision and accuracy in the implant plane, in the implant axis, and the direction/angle of the implant axis. The methodology can also be used to assess the impact of errors in the implant axis on the fit of the structure. Many other values such as cross arch distances can be computed. Applying this methodology to several devices brought to light the huge differences in their behavior. This has a major impact on how the devices need to be tested. The precision both in vitro and in vivo can be determined easily. This led to important conclusions relating to the validity of in vitro tests. The methodology is providing an efficient and uniform method for the analysis of the precision and accuracy of multi-implant structures. It has brought to light the strengths and weaknesses of different technologies not known before.

Effect of Temperature on the Dimensional Accuracy of Irreversible Hydrocolloid Material at Different Storage Time Intervals

Aims: In this competitive arena, dentists are inevitably searching for dimensionally more stable and accurate material to produce precise, effective prosthesis. Amongst many impression materials used on a day-to-day basis, irreversible hydrocolloid impression materials are most commonly utilized due to easy manipulation, hydrophilic nature, elastic recovery, accuracy and cost-effectiveness. The main objective of this study was to observe the effect of temperature and storage time on the accuracy of an irreversible hydrocolloid material.
 Study Design: Experimental and in-vitro study.
 Place and Duration of Study: Department of Prosthodontics and Research Medical Centre, Liaquat University of Medical and Health Sciences, Jamshoro, February 2019 to July 2019.
 Methodology: Total one hundred and five impressions cast models were made using irreversible hydrocolloid impression material (Hygedent) from ideal maxillary dentoform model. There were three temperatures (25°C,35°C and 45°C) and two storage timings (15 minutes and 25 minutes) along with one control group (immediate pouring). Measurements were taken utilizing digital Vernier Caliper. On each cast, two measurements were recorded in a linear manner including anteroposterior (AP) and Cross arch (CA).
 Results: Results revealed that there is a significant difference between anteroposterior dimensional changes of distance from Mesial surface of maxillary right central incisor to distal surface of maxillary right first molar and cross-arch dimensional changes of distance from distal surface of maxillary right first molar to distal surface of maxillary left first molar at different storage temperatures and time intervals. This indicates that the dimensions are increasing directly as storage time and temperature increases which might be because of shrinkage of material due to increase in time of pouring. Shrinkage causes material to pull it towards the tray and increase the dimensions.
 Conclusion: This study concluded that the best results could be obtained with immediate pouring at 25°C temperature as compared to other observed temperatures.

Accuracy of Master Casts Generated Using Conventional and Digital Impression Modalities: Part 2—The Full Arch Dimension

The aim of this study was to evaluate the accuracy of master casts generated by conventional (putty and light body consistencies polyvinyl siloxane and alginate) and digital impression techniques on a typodont master model with full-arch-prepared abutment teeth. The null hypotheses tested were as follows: (1) no statistically significant differences in accuracy between casts made by the two impression modalities and the typodont master model at each of the four locations (horizontal straight, horizontal curved, horizontal cross arch, and vertical), and (2) no statistically significant differences in dimensions measured at each of the four locations between the casts generated using the conventional and digital impression techniques. For the conventional technique, 10 impressions each were made for the typodont model using polyvinyl siloxane and alginate impression materials, and the casts were poured. For the digital technique, the typodont model was scanned 10 times using a TRIOS-3 3Shape intraoral scanner, and the casts were printed. The measurements for the horizontal (anteroposterior and cross arch) and vertical dimensions were made using a stereomicroscope and the accuracy of fabricated casts was expressed as the percentage of deviation from the typodont master model’s values. A one-way ANOVA and Tukey’s test (p < 0.05) were used to analyze the data. In the current study, the only measurement that did not exceed 0.5% in dimensional change was with the stone casts produced by both the 3M ESPE PVS and Kromopan alginate impression materials at the HAPC dimension. The casts generated by impressions made using the 3M ESPE PVS impression material were the most accurate, whereas the casts generated by making digital impressions using the TRIOS-3 3Shape intraoral scanner were the least accurate among the three tested groups. The greatest number of distortions above 0.5% (at all dimensional locations) was produced by the digital models printed using the ASIGA 3D printer.

A case of occlusal reconstruction with a cross arch bridge

A case of occlusal reconstruction with a cross arch bridge

Accuracy of Impression Material During COVID-19 after Sterilization- In vitro Study

Aims: The goal of this research is to assess the effect of steam autoclave sterilization due to the impact of Covid-19 on the accuracy of the elastomer impression materials.
 Study Design: In vitro study.
 Place and Duration of Study: Department of oral and Maxillofacial Prosthodontics, King Abdul-Aziz University, Jeddah; Saudi Arabia, between June 2021 and November 2021.
 Methodology: The following materials were used in this study: fully dentate master cast, metal trays, elastomer impression material (addition silicon), type IV stone. Forte impressions made using the metal tray and elastomer impression materials. The impressions were separated equally into two groups: Control group (C.G), untreated impressions. Sterilized group (S.G): Impressions were sterilized by using the steam autoclave. To make stone castings for each group, they were poured with type IV stone. The traveling microscope was used to evaluate the impression material's dimensional accuracy and detail reproduction with and without autoclave sterilization.
 Results: The cross-arch distance (X) of the master model was measured (41.29 mm), While the cross arch distance (X) in the control group (C.G) of the untreated impressions had a mean and standard deviation of 41.492 ± 0.150 mm. In the tested group (S.G) : the sterilized impression, we found the cross-arch distance (X) had a mean and standard deviation of 41.628 ± 0.223 mm. The master model's Anteroposterior distance (A-P) was measured (21.12 mm). For the control group (C.G) : we found the mean and standard deviation value reading of the A-P distance were 20.899 ± 0.79 mm. For (S.G) group: we found the mean and standard deviation reading of the A-P distance were 19.992± 0.482 mm.
 Conclusion: Steam autoclave sterilization of the elastomer impression material should be considered carefully, especially when fabricating fixed partial dentures. If the impression material is to be used in making diagnostic castings, conventional steam autoclave sterilization of the elastomers impression material may be sufficient for patients.

Evaluation of Cymbopogon Citratus as Disinfectant and its Effect on the Dimensional Stability of the Resultant Gypsum Casts: An in Vitro Study.

BACKGROUND AND AIM: Proper disinfection of impression is probably the most important procedure for dental lab to render it safe for further handling without affecting the accuracy of fine details. In light of these intermingling facts, author aimed to 1) investigate the antimicrobial effect of Cymbopogon citratus on selected microorganism colony and 2) the effect of the disinfectant solution on the dimensional accuracy of the resultant gypsum casts. MATERIALS & METHOD: Initially, tropicalgin Alginate was mixed and total of 20 impressions of the alginate and painted with bacterial colonies. Swabs were further subjected to culture and sensitivity tests for predetermined bacterial strains. Alginate impressions were immersed in glutaraldehyde 2% and Cymbopogon Citratus 30% for 10 minutes (ten each). The swabs were wiped on glass Petri dish and inoculated. The colonial growth was transferred to the glass slide for Gram staining which confirmed presence of Staphylococcus aureus, Streptococcus mutans and Candida albicans in control group. Cross-arch distance between 16 and 26 of the poured samples were compared with the cross arch distance in the typhodont teeth using digimatic vernier caliper. RESULT: Statistical analysis was attempted using SPSS version 22.0. The results of dimensional accuracy of 2% Glutaraldehyde (Group A) mean reading was 55.114, Variance =0.00687 and standard deviation were 0.8289 obtained. The results of dimensional accuracy of 30% Cymbopogan Citratus (Group B) mean reading was 55.403, Variance = 0.0268 and standard deviation were 0.16384 obtained. CONCLUSION: Within the limitations of the study, authors concluded that anti-microbial efficacy of 2% Glutaraldehyde was less in comparison to 30% Cymbopogon Citratus on resultant selected microorganism in this study and dimensional accuracy was superior in Cymbopogan citratus in comparison to glutaraldehyde.

The Effects of Chemical Disinfection on Dimensional Stability among Different Type of Impression Addition Silicon Materials

Introduction: Saliva and blood contaminated impressions are often a source of cross contamination between the clinic and dental laboratory. Explicit communication and observance of an infection control protocol for handling of dental impressions must exist among the office staff as well as between office and dental laboratories. Though disinfection of impression is routinely followed, autoclaving elastomeric impression is an effective method of sterilization them. Objectives: The purpose of this study was to evaluate dimensional stability and detail reproduction of a new addition silicon impression material after disinfection. Methods: In this study, a total of twenty impressions for the master model using heat resistant plastic stock trays. The twenty impressions were divided into two groups according to disinfection technique: (Table 2) Group 1: (n=10) Control group, untreated impressions. (C.G) Group 2: (n=10) Impressions were chemically disinfected. (D.G). after all impressions treatment, they were poured with extra hard stone (type IV) to get stone casts. Dimensional accuracy and detail reproduction of the impression material were evaluated indirectly through the recovered improved stone casts from impressions of the master model using the travelling microscope. Results: Cross arch distance (A): Epoxy resin master model cross arch distance measurement (A) was (41.36 mm). 1.1 Measurements of the cross-arch distance of stone casts Control group (C.G): The mean and standard deviation values of distance (A) in stone models obtained from C.G. were 41.553 ± 0.170 mm. Disinfection group (D.G): The mean and standard deviation values of distance (A) in stone models obtained from D.G were 41.368 ± 0.083 mm. ANOVA test showed that there was a statistically difference shrinkage between the groups (P-value = 0.006). 1.2 Measurement of the dimensional changes in the cross-arch distance of the different groups. The mean and standard deviation values of cross arch distance changes in stone models of C.G. were 0.191 ± 0.170 mm. while dimensional changes in stone models obtained from D.G. were 0.006 ± 0.082 mm. Conclusion: The purpose of this study was to evaluate dimensional stability and detail reproduction of a new addition silicon impression material after disinfection. In this study an epoxy resin master model was duplicated from a modified dentate mandibular model. Within the limitations of this study, it could be concluded that Chemical disinfectant of polyvinyl siloxane impression material can be successfully used in making fixed partial dentures.

Maxillary arch expansion along with fixed mechanotherapy using different expansion devices

Malocclusions can exist in all the three planes of space i.e in antero – posterior, vertical and transverse plane. Transverse discrepancies can manifest as dental, skeletal or functional discrepancies. Maxillary expansion is one of the most common treatment modality for arch length augmentation, posterior crossbite correction and removing cross arch interferences. Skeletal correction is done by orthopedic expansion or surgical expansion. Rapid Maxillary Expansion and Head Gears, produces orthopedic correction. Severe skeletal discrepancies require surgical correction of underlying skeletal deformity by using SARPE (Surgically Assisted Rapid Palatal Expansion) or surgical expansion of palatal shelves by midline osteotomies. Dental correction can be done using Rapid expansion in growing children and by slow expansion using Quad Helix, W Arches, Coffin Spring and certain modification of Jack screw appliances in other cases. In patients treated with fixed mechanotherapy expansions can not only be achieved by Arch wires, auxillary Jockey arches, cross elastics etc. but also by slow or rapid expansion devices that can be amalgamated with fixed orthodontic treatment. In this article, the use of slow maxillary expansion appliances in treatment of the three patients with transverse maxillary deficiency and undergoing fixed mechanotherapy will be discussed. Keywords: Expansion

Evaluation of Biting Force of New Design of Extracoronal Castable Precision Attachment versus Conventional Partial Denture for Treatment of Unilateral Mandibular Distal Extension Area: A Randomized Controlled Trial

PURPOSE: The aim of this study was to evaluate biting force of patients with unilateral mandibular distal extension area treated with two different designs of the removable partial denture (RPD), conventional RPD, and new design of extracoronal castable precision attachment (OT Unilateral attachment).
 MATERIALS AND METHODS: This study was conducted on 16 patients with unilateral mandibular distal extension area with the second premolar is the last abutment teeth. The patients were divided into two equal groups, Group I received conventional RPD, which provides cross arch stabilization and a double Aker clasp was fabricated. Group II received new design of extracoronal castable precision attachment (OT Unilateral attachment). Evaluation of biting force by loadstar sensor, patients of both groups were evaluated at the time of prosthesis insertion, 3, 6, and 1 year later. Statistical analysis performing one-way analysis of variance followed by Tukey’s post hoc test to compare between all follow-up periods within each group, comparison between two groups regarding each follow-up period was performed by independent t-test.
 RESULTS: Both treatments yielded better after-treatment summary when compared with the baseline; however, better results were obtained and showed a statistically significant increase in Group II (OT unilateral design), especially after 3, 6 months, and 1 year later.
 CONCLUSION: From the results of this study, it was concluded that: It is preferable to use the new design of extracoronal castable precision attachment (OT unilateral) being simpler, more comfortable to the patients and give high masticatory efficiency in the form of biting force than conventional RPD.

Class II Kennedy implant assisted mandibular removable partial dentures with and without cross arch stabilization: A strain gauge in vitro study.

Introduction Dental implants and extracoronal attachments were used with Kennedy class II implant assisted removable partial dentures (IARPD) without a major connector. strain gauges were used to detect the microstrains generated around the abutments and dental implants. Materials and Methods Thirty acrylic resin models of a mandibular class II Kennedy received 3 RPD designs; a clasp retained RPD in group I, a unilateral clasp retained RPD without a major connector supported by a dental implant placed once at the first molar and once at the second molar position in group II, and in group III, a clasp free RPD, with extracoronal attachments, supported by a dental implants placed in similar positions to group II. Strain gauges were used to determine which design generated more significant loads, and recorded microstrains were statistically analyzed using the Kruskal-Wallis and Mann-Whitney tests. Results Significantly greater loads around abutment teeth were reported in group II and group III than in group I. The distal placement of the implants resulted in significantly greater microstrains more than the mesial placement in groups II and III, and both placements were of more intensity in group II than in group III. Conclusions A Kennedy class II IARPD can be effectively altered to a bounded space prosthesis by placement of a dental implant in the first rather than the second molar position, and together with an extracoronal attachment, the clasp and major connector can be omitted once the edentulous span is short, and the clinical situation is favorable.

A case of 3 years after treatment with cross arch splint for localized severe chronic periodontitis

A case of 3 years after treatment with cross arch splint for localized severe chronic periodontitis

Evaluation of the trueness and precision of complete arch digital impressions on a human maxilla using seven different intraoral digital impression systems and a laboratory scanner.

An impression accuracy study using a cadaver maxilla was performed using both prepared and intact teeth as well as palatal tissue. Three crown preparations were performed on a cadaver maxilla. Seven different digital impression systems along with polyvinylsiloxane impressions were used to create digital models of the maxilla. Three-dimensional (3D) files of the experimental models were compared to a master model. The 3D files were overlaid and analyzed using a comparison software to create color coded figures that were measured for deviations between the master and experimental models. For scanning tooth structure, only the Planscan was significantly less accurate than the rest of impression techniques. No significant differences in accuracy were found between models created using digital impressions and those created from traditional vinyl polysiloxane impressions with cross arch deviations ranging from 18 to 39 μm for each. Impressions taken using all digital impression systems, save for the Planscan, were able to accurately replicate the tissues of a complete arch human maxilla. Studies examining accuracy of digital impression systems have generally been performed on materials other than dental tissues. Optically, materials such as plastic and metal have properties different from enamel and dentin. This study evaluates accuracy of digital impression systems on human dentin, enamel, and soft tissues.

Evaluation of efficacy of Aloe Vera as a Disinfectant by Immersion and Spray methods on Irreversible Hydrocolloid Impression Material and its Effect on the Dimensional Stability of Resultant Gypsum Cast - An in Vitro Study.

The need to use a natural alternative for disinfecting dental impression materials, which should be biocompatible and effective, led us to evaluate the efficacy of Aloe vera as a disinfectant by immersion and spray method on alginate impression material and its effect on the dimensional stability of the resultant gypsum cast.The efficacy of the disinfection procedures against Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans was evaluated by determining the number of colony-forming units (CFU) recovered after disinfection of alginate discs inoculated with 1x106 CFU for defined intervals with aloe vera solution (99.96%). Dimensional stability was determined from the mean percentage deviation of three measurements that were taken between the fixed points on the casts using a traveling microscope and compared with corresponding measurements from the master model and controls. Statistical analysis of data was determined by analysis of variance.We found out that there is a mean percentage reduction in colony count of S. aureus, P. aeruginosa, and C. albicans after 3 minutes of immersion in aloe vera and after 3 minutes spray disinfection. Complete elimination of all the microorganism cells after 7 min immersion and spray disinfection. There was a statistically significant difference in the increase of the mean anteroposterior (AP) and cross arch (CA) dimension after 3 and 7 minutes immersion in aloe vera. Spraying with aloe vera for 7 minutes was proved to be the most effective disinfection procedure without altering dimensional stability.

"Simpli5y" a noval concept for fixed rehabilitation of completely edentulous maxillary and mandibular edentulous arches: A 3-year randomized clinical trial, supported by a numerical analysis.

To evaluate the clinical outcome of "simpli5y" concept where in 3 and 2 implant placed cross arch in maxilla and in mandible respectively, restored with screw retained prosthesis. Total of 30 patients were randomized, with 15 in group1 with an average of 45 Ncm insertion torque with delayed loading and 15 in group 2 with above 65 Ncm inertion torque with immediate loading with equal number of male and female in each group following parallel design with 3 implants in maxillary and 2 implants in mandibular arch placed which was supported by a 3Dimensional finite analysis comparing the stress dissipation around implants of this concept-"Simplif5y" with All-on-4 concept. Von Mises strain recorded in the bone in the maxillary and mandibular arch models were higher in All-on-four than that in the "simpli5y", which was vice-versa in the framework. Three-year post loading marginal peri implant bone loss for the group 1 was less than group 2. These results, suggest that in both delayed loading and immediate loading protocol that cross arch prostheses can be successfully supported by 3 and 2 implants in maxillary and mandibular arch respectively-"Simpli5y" concept of full mouth restoration.

Comparison of Flexural Strength and Surface Roughness of two Different Flexible and Heat Cure Denture Base Material: An in Vitro Study

To Compare and Evaluate the Flexural Strength and Surface Roughness of Lucitone-FRS, Valplast (Flexible Denture Base Materials) and Trevalon (Heat Cure Denture Base Material). Three stainless steel master dies of dimension 65 × 20 × 3 mm were fabricated and were invested in standard metal denture flask. A total of 60 specimens were fabricated with 20 specimens of each type of denture base material. Fabrication of a Heat Cure Acrylic Denture Base Resin Specimen was Done Followed by Fabrication of Flexible Denture Base Resins Specimen. In the same manner, samples were fabricated for Lucitone-FRS, and Valplast. These specimens were further divided into two subsets; containing 10 specimens each from each group. In one subset, Flexural Strength was Measured while in the other subset, Surface Roughness was measured. The Surface Roughness values were measured using a surface testing machine Mitutoyo-SJ-Series 201 (Japan). The flexural strength of specimens was measured using a 3-point bending test device on universal testing machine. All the results were compiled and Analyzed by SPSS software. Flexural strength was found maximum in the VALPLAST and minimum in LUCITONE. Surface Roughness Test was done on total 10 samples of each material, i.e. Lucitone-FRS, Valplast and Trevalon. Results for Surface Roughness Test are Valplast has maximum Surface-Roughness followed by Trevalon and minimum in Lucitone-FRS on both polished and unpolished surface. Trevalon can be ideal in cross-arch stabilization cases and Valplast and Lucitone FRS can be successfully used in cases of small arch complete dentures and removable partial dentures. The selection of the right denture base material is imperative as it largely affects the overall clinical outcomes and comforts. Results of the present study would aid the dentist in the selection of ideal denture base materials for specific cases like those requiring Cross Arch Stabilization, Small Arch Complete Dentures, and Removable Partial D entures.