Silicone Impression Research Articles

Comparison of fracture resistance of mandibular central incisors following the use of two different spreaders during lateral condensation obturation technique- An in vitro study

The lateral condensation is the most commonly practiced obturation technique during root canal treatment. In this method, the use of spreaders is instrumental in acheiving 3-D obturation. These spreaders can create an unnecessary stress during use, by means of wedging force that might lead to vertical root fracture, resulting in failure of root canal treatment. Sixty extracted mandibular central incisors were taken. All teeth were sectioned 2 mm coronal to CEJ and were wrapped in aluminium foil. The specimens were embedded in acrylic mould. Aluminium foil was scratched and the created space was filled with light body silicone impression material. Then, after working length determination, apical preparation was done with 40 no. K- file. Rest of the canal was prepared using step back technique. The samples were then randomly divided into 3 groups of 20 samples each. Group 1 No obturation (control group). Group 2 Obturation done using stainless steel finger spreaders. Group 3 Obturation done using nickel titanium finger spreaders. After the obturation, all samples were subjected to fracture using metal indenter on the universal testing machine. The load at which fracture occur was recorded. Data thus obtained was subjected to statistical analysis using ANOVA and TUKEY test. The mean fracture resistance of group 1 was highest followed by group 3 (NiTi spreader) and least in group 2 (SS spreader). NITI or SS spreaders can affect the fracture resistance of teeth during lateral condensation obturation technique.

ROLE OF THREE DIFFERENT DISINFECTANTS FOR PREVENTING BACTERIAL GROWTH IN DENTAL IMPRESSION MATERIAL

Background:
 Dental impressions become contaminated with micro-organism from patient’s saliva and blood which can cross-infect stone cast poured against them. The aim of the present study was to compare the efficacy of commercially available disinfection products, one containing glutaraldehyde, sodium hypo chloride and ethanol for disinfection of impressions material.
 Methods: For this investigations, dental impression of 60 patients were taken. Impression was made in 5 mm slices for each disinfectants. Sectioned impression were immersed in gluteral aldehyde, sodium hypo chloride, and ethanol solutions. Antibacterial property of these disinfectants were evaluated by inoculating the sample saline solution into nutrient agar medium.
 Results: There is no significant different between these three disinfecting solution (P<0.05).all these disinfecting solution seems effective against the bacterial growth.
 Conclusions: Addition silicone impressions should always be disinfected after water wash in order to reduce effectively the cross-infection risk. All disinfectants tested showed high antimicrobial efficiency. Ethanol can be good economical alternative for disinfecting addition silicone.

Comparative evaluation of the accuracy of the dental arch display using modern intraoral three-dimensional scanners

BACKGROUND: At present, modern dentists used dental intraoral three-dimensional (3D) scanners routinely in their daily work. Obtaining an optical 3D image of the teeth and dentition helps avoid errors at the stage of obtaining traditional silicone impressions and significantly reduces the level of discomfort during dental procedures. Intraoral scanner systems are commercially available today. Despite their advantages over traditional silicone impressions, the accuracy of the optical impressions obtained during total and subtotal prosthetics on the upper and lower jaw are still questionable.
 AIM: This study aimed to evaluate the accuracy of scanning models of the patients dentition obtained using intraoral scanners and to determine the currently available models of digital devices that are optimal in terms of price and quality.
 MATERIAL AND METHODS: The reference scan (master model) was an optical image of the reference model of the upper jaw of a patient with a full dentition made by additive 3D-printing technology obtained using a laboratory scanner. To level out the shrinkage errors of photopolymerization materials, the resulting model was scanned on the same day using intraoral scanners selected for the study. The obtained scan results were compared with the reference scan of the control group. Based on the measurements made at reference points, the average error value relative to the master model and its precision were calculated for each scanner. In addition to the average values, the error parameters of the scanners in the frontal and chewing sections were calculated, as well as the arc error, which was equal to the difference in the values of the discrepancy at the reference points at which the maximum and minimum values were obtained. The cost and availability of scanners on the domestic market, under the sanctions policy of foreign countries, were also considered.
 RESULTS: The CEREC Primescan AC scanner showed the best accuracy according to the results of model discrepancies. It has an average error of 13.727.34. The arc error was 18.8 microns, and the discrepancies in the frontal area and chewing area were 18 and 6.8 microns, respectively. 3Shape Trios 3 scanner has the closest accuracy, with an average error of 16.285.94 microns. The error value of Aoralscan 3 was 42.0818.34 microns, its arc accuracy was 65 microns, and the discrepancies in the frontal and chewing areas were 33 and 55.1 microns, respectively. Emerald S Mode C had an average error of 35.8422.29 microns, which was higher than that of Medit i500 and Aoralscan 3; however, Aoralscan 3 showed better precision (18.34 microns versus 22.29 microns). According to the comparison results of the models in the MeshLab program, CEREC Primescan AC showed the smallest median of distances (18 microns). The TRIOS 3 and Emerald S Mode C differed from the standard by an average of 29 microns, and Aoralscan 3 scanners had of 33 microns and Medit i500 had 41 microns.
 CONCLUSION: The precision of Aoralscan 3 scanner, which is the best among its analogs in the price category, makes it the most affordable scanner for dental surgical, orthodontic, and orthopedic fields. CEREC Primescan AC is the leader of the premium scanners involved in the study and available in the dental market.

Effects of Various Disinfection Methods on the Material Properties of Silicone Dental Impressions of Different Types and Viscosities.

There is an ongoing search for novel disinfection techniques that are not only effective, cheap, and convenient, but that also do not have adverse effects on the properties of dental impressions. We compared the effects of various methods (UVC, gaseous ozone, commercial solution, and spray) on the dimensional change, tensile strength, and hardness of silicone impressions. Moreover, as a secondary aim, we performed a statistical comparison of the properties of nondisinfected addition (Panasil Putty Soft, Panasil monophase Medium, Panasil initial contact Light) and condensation silicones (Zetaplus Putty and Oranwash L), as well as a comparison of materials of various viscosities (putty, medium-bodied, and light-bodied). Our results revealed that addition silicones had higher dimensional stability, tensile strength, and Shore A hardness compared to condensation silicones. Both traditional (immersion and spraying) and alternative methods of disinfection (UVC and ozone) had no significant impact on the tensile properties and dimensional stability of the studied silicones; however, they significantly affected the hardness, particularly of Oranwash L. Our study demonstrated that, similarly to standard liquid disinfectants, both UVC and ozone do not strongly affect the material properties of most silicones. However, before recommendation, their usefulness for each individual material should be thoroughly evaluated.

Understanding the effect of scan spans on the accuracy of intraoral and desktop scanners

ObjectivesThis study aimed to measure and compare the accuracy (trueness and precision) of intraoral scanners and desktop scanners when scanning different spans. MethodsThree plaster models representing different spans (full arch, half arch, and three teeth) were obtained from conventional silicone impressions of a maxillary typodont and used as the scanning objects. An industrial scanner (ATOS III Triple Scan) was used to scan the three plaster models to obtain reference digital models. The plaster models were then scanned using two intraoral scanners (Trios 3 and Primescan) and two desktop scanners (LS3 and D2000) to obtain test digital models. The reference and test models were imported into professional reverse engineering software for processing and analysis. The root mean square value indicated differences between the reference and test models. Two-way ANOVA and Bonferroni multiple comparison tests were used for statistical analysis. ResultsTwo-way ANOVA tests revealed significant differences in trueness and precision for different scan spans (p < 0.001) and different scanners (p < 0.001), which indicates that the scanner types and scan spans affect the accuracy of the scanner. There was no significant difference in the accuracy of the D2000 at three different scan spans (trueness: 23.82 ± 0.22 µm, 21.53 ± 0.18 µm, and 21.02 ± 0.27 µm respectively; precision: 7.86 ± 0.83 µm, 7.87 ± 1.11 µm, and 7.82 ± 0.84 µm respectively). For the LS3 and the two intraoral scanners, the accuracy of the full arch scan (LS 3, trueness: 33.35 ± 0.47 µm, precision:15.36 ± 3.10 µm; Trios 3, trueness: 46.92 ± 9.23 µm, precision:20.79 ± 3.08 µm; Primescan, trueness: 28.73 ± 0.77 µm, precision:15.74 ± 2.45 µm) was significantly lower than that of the half arch (LS 3, trueness: 27.27 ± 0.43 µm, precision:5.62 ± 0.88 µm; trios 3, Trueness: 22.29 ± 1.50 µm, precision:14.12 ± 2.25 µm; Primescan, trueness: 18.91 ± 0.70 µm, precision:7.94 ± 1.09 µm) and three teeth scans (LS 3, trueness: 24.68 ± 0.36 µm, precision:5.29 ± 0.62 µm; Trios 3, trueness: 16.92 ± 0.78 µm, precision:11.95 ± 2.22 µm; Primescan, trueness: 15.79 ± 0.65 µm, precision:7.68 ± 0.62 µm). ConclusionsThe scan span affected the accuracy of the intraoral scanners, but not necessarily the accuracy of the desktop scanners.

Dental Silicone-based Surgical Guides to Harvest the Chimeric Scapular Flap: Preventing Iatrogenic Vascular Injury.

Summary:The angular branch of the thoracodorsal artery and the periosteal branches of the circumflex scapular artery can be easily injured while harvesting a chimeric scapular flap. Thus, we reported the use of 3D printed scapular models using CT angiography to prepare inexpensive surgical guides from autoclavable dental silicone impressions for scapular flap harvest. Mandibular and scapular models were prepared using a 3D printer for 11 patients undergoing chimeric scapular flap transfer following mandibular resection. During preoperative simulation surgery, we molded dental silicone accordingly with scapular models to produce surgical cutting guides. Six men (54.5%) and five women (45.5%) were included. The average age of patients was 65.4 years. Fourteen bone units were reconstructed as three patients needed two bone segments (27.3%) whereas eight patients required reconstruction of one bone segment (72.7%). The mean flap harvest time and total surgical time were 52.1 min and 633.8 min, respectively. The mean duration for osteotomies and bone plate fixation was 26.2 min. The difference between the length of the preoperative surgical model (64.92 mm) and the postoperative 3D-CT measurements (64.48 mm) was not statistically significant (0.95 mm, P = 0.397). No injuries were caused to the angular and periosteal vessels. Four patients exhibited donor-site seroma (36.4%). The cost of the dental silicone for surgical guide was only $5 per patient. Dental silicone-based surgical guides help minimize the risk of vascular injury while harvesting chimeric scapular flaps. The osteotomies were performed with precision and in a time-efficient manner.

CLIKSS technique for Toronto Bridge with conometric coping technique and intraoral splinting with Dynamic Navigation

The aim of the technique is installing implants and providing fixed teeth with immediate loading thanks to digital design and the use of Navident. It foresees the use of fixtures with cone-morse prosthetic connection connected to conometric abutments of different heights with relative caps; the latter are activated by friction with the walls of the abutment which have a variable angle between 3 and 5 °. The implants are distributed along the entire arch seeking parallelism by limiting the cantilevers as much as possible (6-7 upper implants and 5-6 lower implants). The Navident helps a lot to have perfect parallelism between the implants. A silicone impression on the coupled in situ caps is taken at the end of the surgery, once the flaps have been sutured for the technician. The next day, the technician makes a DEFINITIVE Toronto Bridge prosthesis with Peek or other reinforced thermosetting resin technopolymer. The work is finished by filling the space between the cap and the prosthesis previously excavated by the technician with composite resin, closing the patient's teeth. There were 43 cases between upper jaws and lower jaws; 26 higher cases and 17 lower cases; No complications, 4 implant failures in upper jaws. CLIKSS technique provides intraoral passive fit, simple manufacturing and easy-removable prosthesis for the benefit of the patients

Clinical features of prosthetic treatment in edentuluos patients

BACKGROUND: Social adaptation of patients with complete absence of teeth is associated with fixation and stabilization of prostheses during chewing and speech. It is necessary to take into account the somatic status of the patient, the causes of tooth loss, pay attention to the clinical stages of orthopedic treatment.&#x0D; AIM: Of the study is to increase the efficiency of the orthopedic dentist with full removable prosthetics.&#x0D; MATERIAL AND METHODS: The conditions for obtaining a compression impression are a rigid spoon, silicone impression material of medium viscosity, constant pressure at the time of impression removal. The indication for removing the compression impression is the mucous membrane of the 1st type according to the Supple. The conditions for removing decompression impressions are a perforated individual spoon, liquid-flowing impression material, no pressure on the oral mucosa. The indication for the use of decompression impressions is a thin, atrophied mucous membrane of the oral cavity of the 2nd type according to Supple. It is necessary to use functional impressions combined according to the degree of pressure on the oral mucosa. This implies the peculiarities of manufacturing a rigid base with wax rollers. After determining the central ratio of the jaws and packing the template basis with bite rollers, the doctor applies the impression material differentially to its inner surface. Both templates with bite rollers are inserted into the oral cavity, the doctor controls the central position of the lower jaw, while functional impressions are taken from the upper and lower jaws, taking into account the functional pressure of the patients chewing muscles. This will allow you to evenly distribute the chewing pressure on the oral mucosa. The value of functional rest is determined by measuring two marked points at the base of the nose and on the chin and always exceeds the amount of separation in the state of the central ratio of the jaws by the amount of the interclusal space. Having determined the amount of functional rest, they begin to design the maxillary occlusion pattern, then note the anatomical landmarks. Often, the removal of impressions with a corrective silicone mass is performed in the position of the central ratio.&#x0D; The value of functional rest is determined by a set of anatomical landmarks in a state of maximum possible muscle relaxation in combination with phonetic tests when closing the lips without tension.&#x0D; RESULTS: The determination of the central ratio on rigid bases makes it possible to accurately fix the interalveolar distance. Patients adapt to prosthetic structures faster.&#x0D; The use of a facial arch with an articulator significantly improves the quality of the prosthetic structure, allows you to individualize the anatomical parameters of the patient.&#x0D; When determining the central ratio of the jaws, checking the design of the future prosthesis, cone-beam computed tomography of the temporomandibular joint was used to control the position of the heads of the lower jaw, confirming the correctness of the actions. At the stage of checking the design of the removable prosthesis, phonetic tests were used.&#x0D; CONCLUSION: The use of combined impressions with simultaneous determination of the central ratio of the jaws and control of the position of the heads of the lower jaw can accelerate the process of orthopedic treatment (combining two stages) and adaptation to removable prostheses. To improve speech during treatment, it is necessary to use special phonetic tests that allow you to restore the correct ratio between the jaws, find the optimal position of artificial teeth, determine the boundaries and shape of the basis of the prosthesis and design the optimal prosthesis for each patient.

A Novel Approach to Immediate Implants: The CastleWall Surgical Technique.

Objective: The purpose of this study was to investigate the volumetric stability around immediate implants, in which a 360-degree socket-shield was retained using the CastleWall Surgical Technique (CWST). Material and methods: This retrospective study examined the results of the CWST used for 25 consecutive patients, involving 31 immediate implants. Silicone impressions taken prior to extraction, and at a review appointment were converted to STL files and compared. The median follow-up time was 14.2 ± 5.5 months. Volumetric changes and gingival recession on both buccal and lingual sites were measured. Papillary height changes were also evaluated from available photographs taken before and after treatment. Patients in the study completed a Visual Analogue Scale (VAS) for evaluation of post-operative discomfort and overall satisfaction with this procedure. Results: All implants integrated successfully without complications. Mean loss of buccal and lingual tissue was 0.30 ± 0.32 mm and 0.17 ± 0.27 mm, respectively. Mean recession at the mid-buccal and mid-lingual gingival margin was 0.66 ± 0.64 mm and 0.87 ± 0.84 mm, respectively. Mean recession of the mesial and distal papilla was 0.26 ± 0.55 mm and 0.29 ± 0.52 mm, respectively. Patients reported 97.74 ± 5.60% satisfaction with this procedure using the Visual Analogue Scale (VAS), with minimal post-operative discomfort. Conclusions: The results of this study showed excellent soft tissue stability and aesthetics were achieved using the CWST, with minimal postoperative pain. The other main advantage of retaining a 360-degree socket-shield, is there is more available surface area to lock the implant to the shield to prevent shield migration over time.

Evaluation of dentinal crack propagation, amount of gutta percha remaining and time required during removal of gutta percha using two different rotary instruments and hand instruments - An In vitro study.

One of the most important goal of non surgical endodontic retreatment is the successful removal of gutta percha and sealers from the root canal system. A variety of techniques have been recommended for retreatment procedures for the removal of gutta-percha and sealers with or without the help of adjunctive chemical solvents, by using stainless steel hand files or nickel-titanium rotary files, gate glidden burs, heated instruments, ultrasonic instruments, and lasers 1,3. The current advancements in the design of NiTi instruments have proved efficacious in the removal of filling materials from the root canal wall and various studies have also confirmed their cleaning ability and efficacy 4,5. Nevertheless, the use of rotary instrumentation can lead to the formation of dentinal cracks in the root canal dentin. Many researchers have reported the incidence of crack formation and propagation after the procedure with manual, rotary and reciprocating instruments. The behavior of rotary instruments in the generation of defects have been the point of greatest interest during many years 6. These dentinal cracks can be defined as defects with a complete crack line extending from inner root canal space up to the outer surface of the root when the tensile stress in the root canal wall exceeds the tensile stress of dentin 7. This study was conducted to investigate and to compare the amount of dentinal microcracks formation with various new instrumentation methods and conventional hand filing method. It also looks into amount of gutta-percha removed after retreatment from the canal and the time required for all the instrumentation technique. Sixty extracted human maxillary first molars with curved roots were mounted on addition silicone impression material incorporated in an aluminium hollow block, then instrumented using step-back preparation with 35 size K files. Obturation was done using gutta-percha with AH plus sealer. These were stored for 14 days and divided into three groups Mani GPR, Endostar Re Endo and H file and were subjected to retreatment procedures. Retreatment was considered complete when no filling material was observed on the canal wall and the canal was smooth and free of visible debris. The samples were examined under scanning electron microscope and the number of cracks were calculated. The percentage of root canal filling material and time taken was recorded. The data obtained were analyzed by using descriptive statistics, ANOVA (Analysis of Variance), chi-square test and Scheffe's post hoc test through SPSS for window (version 22.0). All the techniques showed similar amount of crack propagation, with no statistical difference between the group. Retreatment done using H Files required more time and removed less material. The coronal third showed less amount of gutta-percha remnants than the apical third in all groups. All the groups showed a similar amount of crack propagation. Less number of cracks were observed in the coronal one third and more amount of cracks were found at the apical third. Endostar RE Endo rotary instrument proved to be most effective and least time-consuming. Hedstrom Files required more time and removed less material.

Comparison of digital and conventional methods of fit evaluation of partial removable dental prosthesis frameworks fabricated by selective laser melting

Statement of problemThree-dimensional (3D) printing technology may improve the fit of partial removable dental prosthesis frameworks made by selective laser melting. Conventionally, the gaps between definitive casts and prostheses are evaluated by using clinical replicas, but digital evaluations may provide a better alternative. PurposeThe purpose of this in vitro study was to compare digital and conventional methods for evaluating the fit of partial removable dental prosthesis frameworks made by selective laser melting. Material and methodsA printed resin definitive cast representing a Kennedy class II modification 2 design with 5 reference markers was made from a dentiform cast. Twelve cobalt-chromium partial removable dental prosthesis frameworks were fabricated by selective laser melting on this definitive cast with a digital design software program. The gaps between the frameworks and the cast were assessed by using the clinical replica method with a silicone impression material and measuring the thickness at each marker with calipers. Digital casts of each framework and the definitive cast were scanned and then registered with the CloudCompare software program to measure 3D gaps at the 5 reference markers and 3 occlusal rests. The results were analyzed individually for each technique by 1-way analysis of variance (ANOVA) with post hoc Bonferroni tests (α=.05). ResultsFor clinical registration, the mean gap between the frameworks and definitive cast was 13.9 ±7.6 μm. For digital registration, the root mean square gap was 70.7 ±24.2 μm. Statistically significant differences among the gaps for different markers were found for both approaches (P<.05). There were no significant differences among the gaps between the different frameworks. In both situations, the gap measurements were below the 300-μm clinically acceptable standard. ConclusionsBoth registration methods determined whether the fit of a framework fabricated by selective laser melting was within a clinically acceptable standard. The differences in the values produced most likely arose from the different registration methods.

Influence of Implant Placement Depth on Implant Position Reproducibility : Comparison between Silicone Impression and Intraoral Scanner-assisted Optical Impression Methods

Influence of Implant Placement Depth on Implant Position Reproducibility : Comparison between Silicone Impression and Intraoral Scanner-assisted Optical Impression Methods

A Study on the Implant Position Reproducibility of an Intraoral Scanner : Comparison with the Conventional Silicone Impression Method

A Study on the Implant Position Reproducibility of an Intraoral Scanner : Comparison with the Conventional Silicone Impression Method

Применение индивидуального позиционера, спроектированного методом CAD, для световодного зонда при лазерной диагностике микроциркуляции пародонта

Objective: To perform laser Doppler flowmetry (LDF) periodontal microcirculation assessment using custom-made, computer-aided-designed probe holders manufactured by stereolithography (SLA). Methods: 66 young people aged 21-23 years old with clinically healthy periodontium were examined. The first group consisted of subjects where a custom-made probe holder was fabricated using a silicone impression mould technique. The second group consisted of subjects where a custom-made computer-aided-design probe holder made of a photopolymer by SLA was used. The basic microcirculation parameters were analysed to evaluate periodontal microcirculation by the LDF method: the PM – average perfusion value in periodontal tissues; δ – the average square deviation of the amplitude of blood flow fluctuations from the arithmetic mean value, Kv – coefficient of variation (%). Statistical processing of the results was carried out using the software package Statistica 13.0 (StatSoft Inc, USA). Results: Statistical analysis results indicated that the functional characteristics of the periodontal microcirculation using various custom-made fibre optic probe holders used in capillary blood flow monitoring had significant differences p&lt;0.05. The value of the median PM when using a silicone holder in group I was 1.6 times lower than when using a photopolymer holder in group II. The median value of the σ index when using a silicone holder in group I was 2.3 times higher than when using a photopolymer holder in group II. The median value of the Kv when using a silicone holder in group I was 2.5 times higher than when using a photopolymer holder in group II. Conclusion: A photopolymer probe holder, unlike a silicone one, provides a constant fixed distance between the periodontal tissues and the LDF probe, prevents movement or probe displacement, and makes it possible to avoid pressure on the gingival tissue, ensuring high accuracy of laser diagnostics Keywords: Functional diagnostics, LDF, microcirculation, periodontium, CAD, stereolithography.

An in vitro digital comparative evaluation of the accuracy and dimensional stability of vinyl polyether silicone impression material with the conventionally used elastomeric materials scanned using a blue light scanner

Background: The development of material science has allowed integrating qualities of polyether (PE) and Vinyl Polysiloxane (VPS) into a newer material Vinyl polyether silicone (VPES). There is limited literature available on this combination material. The aim was to evaluate and compare the accuracy and dimensional change of elastomeric impression materials with a three-dimensional (3D) approach. Materials and Methodology: Impressions were made of standard tooth model and custom trays using the three monophase impression materials, i.e., Group A–Vinyl polysiloxane (VPS), Group B-Polyether (PE), and Group C-Vinyl Polyether silicone (VPES). All the impressions were digitized and compared on eight predetermined points using a 3D compare software by the superimposition of computer-aided design files of impressions onto that of Standard tooth model. Three-dimensional comparison is repeated after storage of impressions for 1 week to re-evaluate the dimensional stability of the impression materials. Results: The average measurement of mean discrepancies of all the 8 points obtained on day 1 for VPS, PE, and VPES were 75.758 μm, 139.52 μm, and 49.24 μm, respectively, which helps in the determination of accuracy and after interval of 1 week 91.27 μm, 157.25 μm, and 89.76 μm, respectively, which helps to deduce that the linear dimensional change values for Group A, Group B, and Group C were 15.52 μm, 17.73 μm, and 40.52 μm, respectively. Conclusions: Average dimensional accuracy was highest of VPES followed by VPS and PE. Whereas VPS impression material shows the highest dimensional stability after prolonged storage of 1 week, followed by PE and then VPES impression material.

Accuracy of Elastomeric Impression Made with Standard and Dual Arch Tray: An In-vitro Study

Introduction: The dual-arch impression techniques utilise special stock impression trays of various designs. These trays are made of plastic or metal with fabric or mesh material placed across the occlusal surfaces of the teeth connecting their buccal and lingual flanges. These special trays register the impression of the opposing segments of the dentition. The dual arch impression technique is used in dentistry effectively since many decades but there is very little evidence published regarding the effect of different tray design on the accuracy of impression. Aim: To evaluate the accuracy of inter-abutment distance in dies obtained from different dual-arch trays and with those obtained from stock metal trays. Materials and Methods: This in-vitro study was carried out in the Department of Prosthodontics, M.M. College Of Dental Sciences and Research, Mullana, Haryana, India between June 2016 to November 2017. A total of 70 elastomeric impression using heavy and light body addition silicone impression material were made, of the prepared typodont teeth of right mandibular first premolar and first molar for thee- unit fixed partial denture. impressions were grouped into four groups, based on the type of tray used i.e. Group A consisted of impressions obtained from plastic dual-arch trays (n=20), Group B- plastic reinforced with metal dual-arch trays (n=20), Group C- metal dual-arch trays (n=20) and Group D-full stock metal trays (n=10). Group A, B and C were further divided into Subgroup I (working side poured first) (n=10) and Subgroup II (non-working side poured first) (n=10) depending upon the sequence of pouring. The measurements were obtained using travelling microscope and statistical analysis was done using one-way Analysis of Variance (ANOVA) test which was then followed by a post-hoc test. Results: The inter-abutment distance showed a decreased value in all the groups when compared to the master model (p-value &gt;0.05). Percentage decrease in inter-abutment distance was between 0.006% - 0.48%. The results indicated statistical insignificant difference when full arch metal stock tray impression is compared to all dual arch trays impression. There was insignificant difference between the inter-abutment distance obtained using dual arch trays which were poured with working or non working side first. Conclusion: The impressions obtained with both dual arch trays and stock tray, produced dies with distortion in a clinically relevant range. Thus, dual arch trays can be recommended for making impressions of short span fixed partial dentures, and can be considered to be an alternative to the conventional method.

Comparative evaluation of shaping ability of sequential rotary, single rotary, and single reciprocating file systems in simulated curved canals using cone-beam computed tomography: An in vitro study

Comparative evaluation of shaping ability of sequential rotary, single rotary, and single reciprocating file systems in simulated curved canals using cone-beam computed tomography: An in vitro study

Evaluation of the Validity of Digital Optical Microscopy in the Assessment of Marginal Adaptation of Dental Adhesive Interfaces.

Analysis of marginal adaptation of dental adhesive interfaces using scanning electron microscopy has proven to be a powerful nondestructive method to evaluate the quality of adhesion. This methodology is, however, time-consuming and needs expensive equipment. The purpose of this study was to evaluate the possibility and efficiency of using a digital optical microscope (DOM) to perform marginal analysis and to compare it with the scanning electron microscope (SEM) analysis. Fifteen defect-free molars were selected for this study. Class V cavities were prepared and restored with resin composite, and epoxy replicas were obtained from silicone impressions of the restored teeth. Custom-made image analysis software was then used to measure the percentage of the noncontinuous margins (NCM) of each sample. To compare the DOM to the gold standard, SEM, each sample was analyzed 10 times using the DOM and three times using the SEM, by the same experienced operator. The repeatability coefficient and concordance were evaluated, and a Bland and Altman analysis was used for comparison of the two methods of measurements. To validate the DOM analysis method, an ANOVA approach (Gage R R) was used. Repeatability and reproducibility, which are two components of precision to validate the DOM analysis system, were calculated. For this, the same restorations were analyzed by two additional operators three times with the DOM. The duration of each step of the analysis using both methods was also recorded as a secondary outcome. Regarding the repeatability of each method, the Friedman test showed no statistically significant difference within the repetitions of measurements by SEM and DOM (p = 0.523 and p = 0.123, respectively). Moreover, the Bland-Altman analysis revealed a bias of 0.86 and concluded no statistically significant difference between the two methods, DOM and SEM. ANOVA evaluated DOM measurement system variation including the variances of repeatability and reproducibility that represented, respectively, 0.3% and 4% of the variance components. Reproducibility or inter-operator variability represented the principal source of variability with a statistically significant difference (p = 0.024). The time required for analysis with SEM was almost double that of DOM. The use of digital optical microscopy appears to be a valid alternative to the SEM for the analysis of marginal adaptation of dental adhesive interfaces. Further studies to evaluate the effect of training of operators in digital optical microscopy could reveal higher accuracy for this method and inter-operator agreement when experience is gained.

Design parameters of polylactic acid custom trays manufactured by fused deposition modeling for partial edentulism: Consideration of the accuracy of the definitive cast

Statement of problemThe effects of design parameters of polylactic acid (PLA) custom trays manufactured by fused deposition modeling (FDM) on the accuracy of partially edentulous definitive casts have not been thoroughly explored. PurposeThe purpose of this in vitro study was to explore the effects of the impression gap and base thickness of FDM-printed PLA custom trays on the accuracy of maxillary and mandibular definitive casts with Kennedy class II, modification I partial edentulism and to optimize these 2 design parameters. Material and methodsCustom trays with a 1-mm, 2-mm, or 3-mm impression gap and 1-mm, 1.5-mm, or 2-mm base thickness were designed on a pair of maxillary and mandibular resin casts and printed with PLA materials by using an FDM printer. Two-step silicone impressions were made by using these custom trays or stock metal trays on resin casts. Digital scans of definitive casts from these impressions were aligned one by one with those of resin casts. Three-dimensional deviations of the tooth area, mucosal area, and overall area were analyzed by using root mean square (RMS) as a metric. Two-way and 1-way analyses of variance with the RMSs as the dependent variable were carried out (α=.05). ResultsThe accuracy of definitive casts from custom trays with a 2.0-mm or 3.0-mm impression gap and 1.5-mm or 2.0-mm base thickness was significantly better than that of definitive casts from custom trays with a 1.0-mm impression gap or 1.0-mm base thickness and was not significantly different from that of definitive casts from stock metal trays. ConclusionsConsidering the accuracy of definitive casts, the optimal base thickness of FDM-printed PLA custom trays was 1.5 mm or 2.0 mm and the optimal impression gap was 2.0 mm or 3.0 mm for Kennedy class II, modification I partial edentulism.

Correlation between occlusal contact area at various levels of interocclusal thicknesses and masticatory performance.

This study aimed to determine the correlation between occlusal contact area and masticatory performance using BiteEye® , a photo occlusal analysis device and the multiple sieve method. To calculate the occlusal contact area at various levels of interocclusal thicknesses and to measure masticatory performance with peanuts as the test material. Fifty-two adults (30men and 22 women) were enrolled according to specific exclusion/inclusion criteria. The occlusal contact area was measured by obtaining the interocclusal record of the maximum intercuspal position (MIP) using silicone impression material. Occlusal contact area measurements were performed in the ranges of 0-149, 0-89, 0-59, 0-29 and 0-9μm. Masticatory performance was measured by obtaining the median particle size (X 50 ) after converting the weight of comminuted peanuts into size using the multiple sieve method. Statistical analysis was performed at 95% significance level. Interocclusal thickness comparison revealed the highest correlation with X 50 in the 0-149μm range. Stronger correlations between the occlusal contact area and X 50 were observed in cases of 20strokes of mastication (r=-.451) than in cases of 10strokes (r=-.383), in the posterior occlusal contact area (r=-.456) than in the full arch occlusal contact area (r=-.451) and the molar area (r=-.478) than in the premolar area (r=-.296). The larger the occlusal contact area, the higher the masticatory performance; this correlation was statistically significant. Regarding interocclusal thickness, the highest correlation between the occlusal contact area and masticatory performance was observed in the 0-149μm range. GWNUDH IRB 2020-A001.