Edentulous Arches Research Articles

Botulinum toxin and occlusal splints for the management of sleep bruxism in individuals with implant overdentures: A randomized controlled trial

BackgroundThe available treatment options fail to provide definitive or curative management for bruxer patients rehabilitated with implant overdentures (OD). The data regarding Botulinum toxin (BTX) injection as a management strategy for bruxism remains unclear. This randomized, single-blinded, control-group, pretest–posttest prospective trial evaluated the occlusal guard and Botox injections (BTX) effectiveness in managing sleep bruxism (SB) in subjects whose one of the edentulous arches had been restored with the implant-supported OD. MethodsForty-two patients diagnosed with definite bruxism were selected, all of which had implant-retained ODs opposing natural dentition. The participants were allocated randomly to three equal groups. Participants in group I (control group) were instructed to remove the OD at night; group II was managed with conventional occlusal stents. Those in group III were given BTX injections. New ODs were constructed for all groups, and all ball attachments were replaced with a new nylon cap. A baseline assessment (one month of OD insertion) of patient satisfaction and sleep quality was conducted, and then again at 3, 6, 9, and 12 months of treatment. Subjective sleep quality was evaluated using Pittsburgh Sleep Quality Index (PSQI). Patients’ satisfaction was evaluated using Temporomandibular disorders/numeric scales (TMD/NS). Prosthodontic (mechanical) complications were recorded during the follow-up period. ResultsGroup III showed a statistically significant improvement in patient satisfaction and sleep quality compared to the other two groups at 3, 6, 9, and 12 months follow-up period (P = 0 0.001, 0.0001, 0.0013, and 0.0001 respectively). Regarding prosthodontic (mechanical) complications, the highest number of events was revealed in the control group. ConclusionsBTX and occlusal appliances effectively improve patient satisfaction and sleep quality of Bruxer patients rehabilitated with single arch implant overdentures.

Stress distribution and patient satisfaction in flexible and cast metal removable partial dentures: Finite element analysis and randomized pilot study

PurposeTo compare stress distribution in polyacetyl based flexible RPD (FRPD) with cast metal RPD (CRPD) by using three-dimensional finite element analysis (FEA) and patient satisfaction by using OHIP-14 questionnaire in participants with Kennedy's class I partially edentulous mandibular arch rehabilitated with CRPD and FRPD. Material and methodsFor FEA, 3D models of Kennedy's class I partially edentulous mandibular arch, CRPD in chrome-cobolt alloy, and polyacetyl based FRPD were geometrically modelled and subjected to a vertical load of 100 ​N bilaterally. The in vivo comparison of satisfaction was assessed by enrolling 22 participants with Kennedy's class I partially edentulous mandibular arch. After randomization, 11 participants were rehabilitated by CRPD (group C), and 11 participants by polyacetyl based FRPD (group F). OHIP-14 questionnaire in Hindi language was filled at 1 week and 1 year after denture insertion. ResultsVon Mises stress distribution in CRPD was maximum in mesial rest seat of the primary abutment (100 ​MPa) and minimum for edentulous ridge (7 ​MPa on bone and 6 ​MPa on mucosa). Von Mises stress distribution for polyaccetyl based FRPD was maximum in ridge (25 ​MPa) and minimum in periodontal ligament of the second premolar (3 ​MPa). Patient satisfaction in group F was significantly more than in group C at end of 1 year (P ​= ​.0158). ConclusionFRPD is useful in periodontally compromised abutment teeth and CRPD in resorbed ridge conditions. Patient satisfaction is more with polyacetyl based flexible RPD when compared with cast metal RPD at the end of 1 year.

Digital verification and correction of digital intraoral scans for fixed implant rehabilitation of edentulous arches: A dental technique

A method is described for the verification and correction of a digital scan of a complete arch implant-supported prosthesis for a completely edentulous patient. The technique provides an efficient way to integrate a highly accurate and precise scan of an implant index cast with a digital intraoral implant scan by using a computer-aided design and computer-aided manufacturing (CAD-CAM) software program. This method allows dental professionals to validate and, if necessary, correct the implant positions in the scan without the need for a conventional impression.

Effect of tooth loss on rugae pattern in complete and partially edentulous individual: A forensic perspective

Background: Preservation of palatal rugae plays an important role in prosthetic rehabilitation and in forensic identification when the individual has no teeth either completely or partially owing to its resistance and stability. However recent studies have shown substantial rugae pattern changes are caused by tooth loss of prolonged duration. Aim: The present study was carried to compare and evaluate the effect of tooth loss on rugae pattern among completely and partially edentulous maxillary arch individuals as a reliable personal identification tool. Methodology: A total of 50 participants were divided into two groups comprising of 25 completely edentulous (Group A) and 25 partially edentulous (Group B) individuals. Impressions, maxillary casts were made and the number, type of rugae patterns were recorded using graphite pencil and tracing paper every 3 month over a period of 1year based on Martins dos Santos classification system. Results: More complex patterns (line, curve, circle, bifurcated, sinnous) are observed in Group B with significant differences between the mean values of line, bifurcated and circle pattern when compared to Group A. Simultaneously mean differences in sinnous pattern (Group A) and Sinnous, Line pattern (Group B) within the group were also seen over a period of 1 year. Conclusion: The present study thus showed significant differences in the rugae pattern between both the groups and greater changes with complex patterns were observed in partially edentulous group when compared with the complete edentulous group.

Management of maxillary single denture fractures: An enigma

Background: The patient’s first complete denture experience is predominantly with the single maxillary denture. The opposing mandibular dentition is usually intact or restored by fixed partial dentures or removable partial dentures. In many instances no attempt has been made to restore a partially edentulous mandibular arch. One of the most common prosthodontic failures encountered is the fracture and failure of the single maxillary denture. This often results in continuous repair of the denture. Often, remaking the denture is the best course to follow. Objective: This article will describe the clinically related causes of single maxillary complete denture fracture and propose preventive and corrective measures. Methods: Electronic searches were performed for articles published in PubMed and manual searches were performed in various journals relevant to the topic of removable prosthodontics. Key words such as maxillary, single, denture, reinforcement were used, Initially, 432 articles were found of which 177 articles were selected by electronic and manual searches from 2005 up to 2020 with few classic articles. After exclusion of 152 articles based on the exclusion criteria, 25 articles were finally included in the review. Conclusion: Factors that contribute to the fracture and failure of the single maxillary denture have been discussed to summarize this review, reinforcements within prostheses undoubtedly had some efficacy in improving the mechanical properties, but the levels varied by material, form, and position of the reinforcement.

A Comparison of Full Arch Trueness and Precision of Nine Intra-Oral Digital Scanners and Four Lab Digital Scanners.

(1) Background: The purpose of this study is to evaluate the full arch scan accuracy (precision and trueness) of nine digital intra-oral scanners and four lab scanners. Previous studies have compared the accuracy of some intra-oral scanners, but as this is a field of quickly developing technologies, a more up-to-date study was needed to assess the capabilities of currently available models. (2) Methods: The present in vitro study compared nine different intra-oral scanners (Omnicam 4.6; Omnicam 5.1; Primescan; CS 3600; Trios 3; Trios 4; Runyes; i500; and DL206) as well as four lab light scanners (Einscan SE; 300e; E2; and Ineos X5) to investigate the accuracy of each scanner by examining the overall trueness and precision. Ten aligned and cut scans from each of the intra-oral and lab scanners in the in vitro study were brought into CloudCompare. A comparison was made with the master STL using the CloudCompare 3D analysis best-fit algorithm. The results were recorded along with individual standard deviation and a colorimetric map of the deviation across the surface of the STL mesh; a comparison was made to the master STL, quantified at specific points. (3) Results: In the present study, the Primescan had the best overall trueness (17.3 ± 4.9), followed by (in order of increasing deviation) the Trios 4 (20.8 ± 6.2), i500 (25.2 ± 7.3), CS3600 (26.9 ± 15.9), Trios 3 (27.7 ± 6.8), Runyes (47.2 ± 5.4), Omnicam 5.1 (55.1 ± 9.5), Omnicam 4.6 (57.5 ± 3.2), and Launca DL206 (58.5 ± 22.0). Regarding the lab light scanners, the Ineos X5 had the best overall trueness with (0.0 ± 1.9), followed by (in order of increasing deviation) the 3Shape E2 (3.6 ± 2.2), Up3D 300E (12.8 ± 2.7), and Einscan SE (14.9 ± 9.5). (4) Conclusions: This study confirms that all current generations of intra-oral digital scanners can capture a reliable, reproducible full arch scan in dentate patients. Out of the intra-oral scanners tested, no scanner produced results significantly similar in trueness to the Ineos X5. However, the Primescan was the only one to be statistically of a similar level of trueness to the 3Shape E2 lab scanner. All scanners in the study had mean trueness of under 60-micron deviation. While this study can compare the scanning accuracy of this sample in a dentate arch, the scanning of a fully edentulous arch is more challenging. The accuracy of these scanners in edentulous cases should be examined in further studies.

Digital Workflow to Fabricate Complete Dentures for Edentulous Patients Using a Reversing and Superimposing Technique

This technical procedure demonstrates a 4-step completely digital workflow for the fabrication of complete dentures in edentulous patients. The digital scan data of the edentulous arches were obtained using an intraoral scanner, followed by the fabrication of modeless trial denture bases using additive manufacturing. Using the trial denture base and a wax rim assembly, the interarch relationship was recorded. This record was digitized using an intraoral scanner and reversed for each maxillary and mandibular section individually. The digital scan data directly obtained using the intraoral scanner were superimposed over the reversed data, establishing a proper interarch relationship. The artificial teeth were arranged virtually and try-in dentures were additively manufactured. Subsequently, the gingival and tooth sections were additively manufactured individually and characterized. Thus, fabrication of digital complete dentures can be accomplished using digital data characteristics. The workflow includes data acquisition using an intraoral scanner, data processing using reverse engineering and computer-aided design software programs, and additive manufacturing.

Trueness and precision of complete-arch photogrammetry implant scanning assessed with a coordinate-measuring machine

Statement of problemPhotogrammetry technology has been used for the digitalization of multiple dental implants, but its trueness and precision remain uncertain. PurposeThe purpose of this in vitro investigation was to compare the accuracy (trueness and precision) of multisite implant recordings between the conventional method and a photogrammetry dental system. Material and methodsA definitive cast of an edentulous maxilla with 6 implant abutment replicas was tested. Two different recording methods were compared, the conventional technique and a photogrammetry digital scan (n=10). For the conventional group, the impression copings were splinted to an additively manufactured cobalt-chromium metal with autopolymerizing acrylic resin, followed by recording the maxillary edentulous arch with an elastomeric impression using an additively manufactured open custom tray. For the photogrammetry group, a scan body was placed on each implant abutment replica, followed by the photogrammetry digital scan. A coordinate-measuring machine was selected to assess the linear, angular, and 3-dimensional discrepancies between the implant abutment replica positions of the reference cast and the specimens by using a computer-aided design program. The Shapiro-Wilk test showed that the data were not normally distributed. The Mann-Whitney U test was used to analyze the data (α=.05). ResultsThe conventional group obtained an overall accuracy (trueness ±precision) value of 18.40 ±6.81 μm, whereas the photogrammetry group showed an overall scanning accuracy value of 20.15 ±25.41 μm. Significant differences on the discrepancies on the x axis (U=1380.00, P=.027), z axis (U=601.00, P<.001), XZ angle (U=869.00, P<.001), and YZ angle (U=788.00, P<.001) were observed when the measurements of the 2 groups were compared. Furthermore, significant 3-dimensional discrepancy for implant 1 (U=0.00, P<.001), implant 2 (U=0.00, P<.001), implant 3 (U=6.00, P<.001), and implant 6 (U=9.00, P<.001) were computed between the groups. ConclusionsThe conventional method obtained statistically significant higher overall accuracy values compared with the photogrammetry system tested, with a trueness difference of 1.8 μm and a precision difference of 18.6 μm between the systems. The conventional method transferred the implant abutment positions with a uniform 3-dimensional discrepancy, but the photogrammetry system obtained an uneven overall discrepancy among the implant abutment positions.

Evaluation of Correlation between Vitamin D Levels and Implant Stability in Indian Population: A Prospective Study in Bangalore.

Dental implants have become a definitive method for the esthetic and functional rehabilitation of both partially and completely edentulous arch. There is a significant role of vitamin D in bone metabolism and there are only few human studies that evaluate the effect of vitamin D deficiency on stability of dental implants. The study thus aims to evaluate the correlation of vitamin D deficiency and implant stability in delayed endosseous implant. The study included 20 subjects of either gender in the age group of 20-50years, who required implant placement for rehabilitation of partially edentulous condition. Vitamin D status was evaluated for all subjects preoperatively. Implant stability was checked postoperatively at three months and six months using Electronic Technology Resonance Frequency Analysis. The study found that for every 1ng/ml increase in Vitamin D levels, the implant stability Quotient value (ISQ) significantly increased by 0.48 at 3months and 0.62 units at 6months, which was statistically significant at P = 0.01 and P = 0.002, respectively. Statistical analysis was done using Student Paired t test, Pearson Correlation test and Simple Linear regression analysis. Albeit the smaller sample size, the results of the study showed the positive influence of vitamin D on stability of implant. The study thus emphasizes on the significance of screening the vitamin D status of subjects prior to implant placement.

Intaglio surface trueness of milled and 3D-printed digital maxillary and mandibular dentures: A clinical study

Statement of problemWhile the dimensional accuracy of the intaglio surface of a removable complete denture is key to its adaptation, comfort, and clinical performance, information on the ability of milling and 3D-printing workflows to accurately reproduce this surface is lacking. PurposeThe purpose of this clinical study was to compare the trueness of the intaglio surface of milled and 3D-printed removable complete digital dentures. Material and methodsIntraoral scans were obtained from 14 participants for a total of 20 edentulous arches. Ten maxillary and 10 mandibular denture bases were then designed and fabricated with a completely digital workflow, both with milling and 3D-printing. Fabricated dentures were digitized with the same intraoral scanner used to obtain intraoral digital scans of the edentulous arches. Standard tessellation language (STL) files of the printed and milled denture bases were used for 3D analysis and comparisons with the STL file of the corresponding designed denture base. Specifically, a reverse engineering software program was used to trim and extract intaglio surfaces, align them, and measure their global mean 3D distance. In order to evaluate the homogeneity of production accuracy of each manufacturing process, the intaglio surfaces were also divided into several regions of interest and the corresponding 3D distances measured. Within- and between-group differences and maxillary and mandibular dentures differences were assessed with parametric and nonparametric tests (α=.05). ResultsMilling showed a global better trueness of the entire intaglio surface (-0.002 mm) than 3D-printing (0.018 mm), both for the whole data set (P<.001) and for maxillary (P=.032) or mandibular (P=.049) denture base subgroups. Within each fabrication technology, maxillary (P<.11) and mandibular dentures (P=.2) showed no significant difference in trueness. Measured deviations were significantly different from zero for the 3D-printed dentures (P<.001), but not for the milled dentures (P=.487). Additionally, for milled dentures, no significant difference in trueness was found among the 11 regions of interest identified for the maxillary dentures (P=.085) and the 13 regions of interest for the mandibular dentures (P=.211). Conversely, 3D-printing showed significant variations in trueness among the same zones of interest, both in maxillary (P<.001) and mandibular (P=.004) dentures. ConclusionsWithin the limits of the manufacturing methodologies used for complete dentures, milling can provide a slightly better trueness of the intaglio surface than 3D-printing, with less variation across several zones of interest. However, given the magnitude of such differences, they may be reasonably considered to be of limited, if any, clinical significance.

Long-Term Clinical Behavior and Complications of Intentionally Tilted Dental Implants Compared with Straight Implants Supporting Fixed Restorations: A Systematic Review and Meta-Analysis.

Simple SummaryFollowing tooth loosening due to periodontal disease, caries, trauma, or tumoral processes, bone resorption and remodeling of the alveolar ridge makes the insertion of implants difficult. A number of bone augmentation techniques are available to treat atrophic jaws. However, when posterior bone is lacking and extensive bone augmentation surgeries are rejected by the patient, placing distally tilted posterior implants may offer a valid therapeutic option for implant-supported restorations. This treatment modality places the implants in preexisting bone, improving bone anchorage and prosthetic support. Nevertheless, some studies suggest that for tilted implants, bending moments are greater at the level of the angled abutment.The aim of this study was to assess the long-term clinical behavior of straight implants in comparison with intentionally tilted dental implants (ITDI) supporting fixed restorations in partial or total edentulous arches, analyzing implant survival and success rates, complications, and marginal bone loss (MBL) after >5 years of function. An electronic search was conducted in five electronic databases (MEDLINE/Pubmed, Embase, Web of Science, Scopus, and Cochrane Central Register of Controlled Trials) supplemented by a manual search. The electronic and manual search identified 1853 articles, of which 8 articles were selected for analysis. Out of a total of 3987 dental implants, 2036 were axial dental implants and 1951 tilted. Similar results were found in implant survival or overall implant success rates. Moreover, no statistically significant differences were found in MBL (p = 0.369; MD 0.116 mm (−0.137; 0.369) 95% CI) The prosthodontic/biological complications reported in the articles were very diverse and irregularly distributed. This systematic review suggests that there is no difference between tilted compared with straight dental implants in the medium-long term (>5 years). However, further research is needed to generate long-term data and confirm the present review’s findings.

English

An accurate impression of the edentulous arch is of utmost importance in the rehabilitation of completely edentulous cases. The steps that follow the impression making are highly influenced by the accuracy of the impression. In order to overcome the manual inadequacies and to improve the accuracy, various advancements have been made manually as well as digitally. Computer-aided design/computer-aided manufacturing (CAD / CAM)is one such digital advancement, which primarily aims at scanning the edentulous arches, followed by subsequent designing of the dentures and processing through various methods such as milling or 3d printing. A major drawback of using CAD / CAM technology is its high cost. Photogrammetry, as a proof of concept, works on the principle of obtaining reliable information about physical objects through the process of recording, measuring and interpreting photographic images. Recently photogrammetry has been gaining interest in the field of dentistry. It can be used as a more cost-effective alternative for diagnosis, treatment planning and fabrication of surgical guides and in maxillofacial prosthetics. In the current article, a novel 360-degree mobile phone scanner was devised which rotates around the object and takes images in order to compute a 3d image, which can be further used for treatment planning and fabrication of dentures.

Assessment of the Effect of Complete Dentures on Respiratory Performance: A Spirometric Analysis.

Background:Among the vital functions, respiration can be claimed to be one of the most important. A thorough understanding of the patient should be an important aspect a prosthodontist should dwell into so as to predispose patients to acknowledge the kind of prosthesis they require. Hence, the present study was conducted for assessing the effect of complete dentures on respiratory performance.Materials and Methods:Fifty patients with the presence of complete edentulous arch and who had a history of complete denture usage for at least 5 years were enrolled. All the spirometric procedures were performed by trained technicians. A diagnostic spirometer was employed for performing the spirometric test. Testing was carried out in the following steps: Stage 1: testing in the absence of denture, Stage 2: testing in the presence of both dentures, Stage 3: testing in the presence of maxillary denture only, and Stage 4: testing in the presence of mandibular dentures only. Forced vital capacity (FVC) value, peak expiratory flow (PEF) value, forced expiratory volume in 1 s (FEV1) value, and forced expiratory flow 25%–75% (FEF25–75) value were recorded with the spirometric test. Analysis of all the results was done by SPSS software.Results:The spirometric value of FVC, PEF, FEV1, and FEF25–75 in the absence of both maxillary and mandibular dentures (Stage 1) was found to be 3.18, 5.83, 2.44, and 2.80, respectively. The spirometric value of FVC, PEF, FEV1, and FEF25–75 in the presence of both maxillary and mandibular dentures (Stage 2) was found to be 3.09, 5.67, 2.41, and 2.67, respectively. While analyzing statistically, it was seen that there was a significant decrease in the value of spirometric variables in the presence of dentures.Conclusion:Chronic denture wearer edentulous patients are subjected to the risk of development of spirometric alterations. Hence, these patients should be given timely instructions about the various respiratory exercise protocols.

Tilted versus Short Implants Supporting Mandibular Fixed Detachable Prosthesis (In vitro study)

Purpose: This study aimed to evaluate strain induced in implants supporting fixed detachable prosthesis with different implant protocols using strain gauge analysis. Material and methods: This stress analysis study used two 3D models simulating a completely edentulous lower arch to support and retain fixed detachable prostheses. In the first model four implant beds were considered; two anterior implants oriented axially and two posterior implants placed at the premolar region tilted 30 degrees. In the second model implant beds were designed with two anterior implants oriented axially and two short posterior implants 8 mm length placed in the first molar region oriented axially. Standardized static load was applied unilaterally by using a loading device (universal-testing machine). Strain gauge was used to measure strains induced in each implant. Results: Regarding the loaded side: Strain induced in the anterior implant and in the lingual and distal aspect of the posterior implant in the first model has shown higher strains compared to the second model. This difference was statistically insignificant in the anterior implant and in the lingual aspect of the posterior implant, while strains induced in the distal aspect of the posterior implant was statistically significant higher in the first model compared to the second model. Conclusion: With the limitation of this in vitro study, it can be concluded that short implants induce less stresses distally than tilted implants.

Influence of Different Factors on the Accuracy of Digital Impressions of Multiple Implants: An In Vitro Study.

To investigate the effect of implant angulation, non-free-end partial edentulism, and number of scan bodies on the accuracy of digital impressions of multiple implants in partially edentulous arches. Four reference models of partially edentulous mandibles with implants (RM1, RM2, RM3, and RM4) representing different intraoral situations were each scanned 10 times by an intraoral scanner. Reference scans were obtained by a laboratory scanner. Test scans were compared with reference scans to obtain the distance deviations (Δd) and angular deviations (Δθ) between scan bodies for trueness assessment. Differences among the repeated test scans of each model were measured and recorded as Δdp and Δθp for precision assessment. The Student t test (α = .05) was used to compare Δd, Δθ, Δdp, and Δθp of different reference models, including RM2 vs RM1 (effect of non-free-end partial edentulism), RM3 vs RM1 (effect of implant angulation), and RM4 vs RM1 (effect of number of scan bodies). The implant with 17-degree angulation in RM3 showed significantly lower Δd, Δθ, and Δθp compared with the parallel implant in RM1 (Δd: P = .0382, Δθ: P = .0267, Δθp: P = .0417). The RM2 of non-free-end partial edentulism had lower distance and angular deviations than RM1, but without a significant difference. The number of scan bodies had no significant effect on the Δd, Δθ, Δdp, and Δθp of RM4 and RM1. Angulated implants showed better accuracy of digital impressions in partially edentulous arches compared with parallel implants. Non-free-end partial edentulism was attributed to improved accuracy, while the number of scan bodies showed no effect.

Restorative Space Analysis by Jaw Motion Tracking Using a Template in Completely Edentulous Patients

Improvements in computer-aided design/computer-aided manufacturing technologies have led to multiple attempts being made to simplify and improve the workflow of prosthesis fabrication for completely edentulous patients. However, most attempts still involve the conventional methods of impression-making and recording the maxillomandibular relationships using alginate, rubber impression materials, and wax materials. In the case of a completely edentulous arch, the presence of movable tissues and the absence of stable landmarks make it difficult to perform direct digitization using an intraoral scanner and to digitally determine the vertical dimension. In the alternative technique described herein, data are obtained by scanning a template such as the patient’s existing old dentures and jaw movement data using target materials and an optical scanner, and an appropriate maxillomandibular relationship that has the desired restorative space is determined on the basis of the obtained trajectory of mandibular movements while opening and closing the mouth. After designing dentures on the basis of the newly established maxillomandibular relationships and performing a try-in process, the final dentures can be manufactured. This alternative technique can reduce the need for multiple visits and complex procedures, improving the workflow for fabricating prostheses with the correct maxillomandibular relationships for individual patients.

English

Among the numerous techniques of oral rehabilitation, precision attachments are considered as a good treatment option in removable (RPD) as well as fixed partial dentures (FPD). Precision attachments enhance patient’s self-confidence and selfimage as they help in facilitating aesthetic, functional and retentive replacement of teeth that are missing in the oral cavity. They can improve the aesthetics by eliminating the clasp assembly in cast partial dentures (CPD). This particular case report explains the treatment sequence and approach for the utilisation of attachments in a Kennedy Class 2 situation. A successful removable partial denture includes a precise diagnosis with meticulous treatment planning. However, re-establishment of partially edentulous arch is particularly challenging in distal extension situations classified as Kennedy’s class 1 or 2 conditions.1 In such clinical cases, where a fixed prosthesis cannot be fabricated, a prosthodontist often suggests an implant retained prosthesis that is not routinely possible because of the insufficient available bone width and height.2 Thus to ensure functional and aesthetic substitution of lost teeth, an attachment secured RPD can be considered as a good treatment option in such cases. Attachments are constructed in a ready to place form (pre-fabricated) known as precision attachments. Another one is semi precision attachment where the segments have to be constructed by dentists or dental technicians because it requires casting for incorporating into fixed unit of restoration.3 Hence precision attachments are considered as possible alternatives when patients demand for a fixed restoration in distal extension cases. Various extra coronal attachments are available and used in distal extension cases. Preci-Sagix is considered as an ideal extra coronal attachment for removable partial dentures and also in over denture cases. It is accessible in two sizes, 1.7 mm mini or 2.2 mm standard and is selected according to the permitted space. The male component is available in three varieties, a plastic castable pattern (any hard alloy), cast to no prax (only non-precious alloy) and a threaded male and base ring (2.2 mm size only).4 These attachments produce vertical, horizontal and rotational movements during its function which supports the prosthesis by transferring harmful forces from the abutments to the supporting structures by its passive movement, which helps in the rehabilitation of distal extension cases.5 This case report explains restoration of partially edentulous arch by incorporating a Preci Sagix attachment in mandibular cast partial denture retained by a six-unit FPD and a maxillary conventional cast partial denture.

Trueness of a device for intraoral scanning to capture the angle and distance between implants in edentulous mandibular arches

Statement of problemThe digitalization of completely edentulous arches presents limitations because of the lack of anatomic structures for best-fit alignment during the image generation process of the scanner’s software program. PurposeThe purpose of this clinical study was to evaluate a new device for intraoral scanning and to analyze its usefulness in capturing the 3-dimensional (3D) position of implants in edentulous mandibular arches. Material and methodsThe 3D positions of 40 implants in 10 participants with fixed interim mandibular prostheses were evaluated by comparing 3 scanning techniques. Images were generated in 2 experimental groups, with digital scan bodies (group SC) and with the scanning device (group SD) and in a control group (group CT) in which images were obtained by laboratory scanning of casts produced from splinted impression copings. The standard tessellation language (STL) files were superimposed by using a reverse engineering software program to measure the 3D coordinate system. Variations in implant linear displacements (Δx, Δy, and Δz), total 3D displacement (Δx2+Δy2+Δz2), and angle projections (ΔθXY, ΔθXZ, and ΔθYZ) were statistically analyzed (α=.05). The distances between the implants were also measured. The Spearman correlation coefficient (α=.05) was used to find the correlation between the 3D coordinates and the distances between the implants. ResultsGroup SD had lower values for linear displacement than group SC; however, this difference was not statistically significant except for implant #2. The overall evaluation showed a significant difference with better accuracy for group SD. Concerning angular displacements, group SD showed lesser angular variation for the 3 projection planes. For the distances between the implants, significant differences were only observed for the “all” assessment in which group SD behaved similarly to group CT, while group SC showed the highest values (P<.05). No correlation was detected between the axes (x, y, and z) and the distances between the implants. ConclusionsThe evaluated scanning device led to improved trueness for linear, angular displacements, and distances between implants in mandibular edentulous arches.

Comparative study of the accuracy of an implant intraoral scanner and that of a conventional intraoral scanner for complete-arch fixed dental prostheses

Statement of problemMost of the available digital systems are designed to image teeth and soft tissue rather than dental implants. However, although some are marketed specifically to record implant position, whether these products are better for implant scanning is unclear. PurposeThe purpose of this in vitro study was to compare the accuracy of an implant intraoral scanner (PiC camera) with that of an intraoral scanner (TRIOS 3) for 6 implants placed in completely edentulous arches. Material and methodsTwo maxillary master models with 6 external hexagonal Ø5.1-mm implants were used, one with parallel and the other with angled implants. The reference values were obtained with a coordinate measuring machine. Ten scans were made per model (parallel and angled) and system (intraoral and implant) (n=10), after which the 3-dimensional coordinates for each implant were determined with a computer-aided design software program and compared with the linear and angular reference values. Statistical significance was determined with the Student t test (α=.05). ResultsStatistically significant differences (P<.001) were found in both precision and trueness. The overall errors relative to the reference in the parallel implant-supported casts based on the implant scanner were 20 μm (P=.031) and 0.354 degrees (P=.087) compared with 100 μm (P<.001) and 1.177 degrees (P<.001) in the cast based on conventional digital scans. The global errors in the angled implant casts were 10 μm (P=.055) and 0.084 degrees (P=.045) for the implant digital scans and 23 μm (P=.179) and 0.529 degrees (P<.001) for the conventional digital scans. ConclusionsThe implant intraoral scanner delivered greater precision and trueness than the conventional instrument for imaging complete-arch implant-supported prostheses.

Evaluation of complete-arch implant scanning with 5 different intraoral scanners in terms of trueness and operator experience

Statement of problemThe intraoral scanning of the edentulous arch might be challenging for an inexperienced operator because of the large mucosal area and the use of scan bodies. PurposeThe purpose of this ex vivo study was to compare the trueness of 5 intraoral scanners in replicating implant scan bodies and soft tissues in an edentulous maxilla and to investigate the effects of operator experience. Material and methodsThe maxilla was resected from a fresh cadaver, 5 implants placed, and a reference scan made. Eight scans were made by experienced operators and 8 by an inexperienced operator with each scanner (iTero Element 2, Medit i500, Primescan, TRIOS 3, TRIOS 4). The implant platform deviation was measured after complete surface alignment and after scan body alignment. Deviation data were analyzed with a generalized linear mixed model (α=.05). ResultsAfter complete surface alignment, the mean ±standard deviation implant platform deviation was higher for the inexperienced operator (421 ±25 μm) than for experienced ones (191 ±12 μm, P<.001) for all scanners. After scan body alignment, no significant differences were found between operators for Element 2, Primescan, and TRIOS 3. The experienced operators produced a lower deviation for TRIOS 4 (35 ±3.3 μm versus 54 ±3.1 μm, P<.001), but higher deviation for i500 (68 ±4.1 μm versus 57 ±3.6 μm, P<.05). The scanner ranking was Element 2 (63 ±4.1 μm), i500 (57 ±3.6 μm, P=.443), TRIOS 4 (54 ±3.1 μm, P=.591), TRIOS 3 (40 ±3.1 μm, P<.01), Primescan (27 ±1.6 μm, P<.001) for the inexperienced operator and i500 (68 ±4.1 μm), Element 2 (58 ±4.0 μm, P=.141), TRIOS 3 (41 ±2.8 μm, P<.001), TRIOS 4 (35 ±3.3 μm, P=.205), Primescan (28 ±1.8 μm, P=.141) for the experienced operators. ConclusionsMucosal alignment greatly overestimated the platform deviation. The intraoral scanners showed different trueness during the complete-arch implant scanning. The operator experience improved the trueness of the edentulous mucosa but not implant platform deviation.