Abutment Teeth Research Articles

Dental practitioners’ knowledge and perception of root canal treatment in abutment teeth for fixed partial dentures – A questionnaire-based survey

ABSTRACT Background: During fixed prosthodontic operations, the pulp is frequently subjected to mechanical and thermal strain. The level of pulpal and thermal injury is determined by parameters such as the amount of residual dentin, the heat generated, and the permeability of the dentinal tubules. Nevertheless, there is no accurate technique to gauge the pulpal response and the effectiveness of the treatment, the heat generated, and the permeability of the dentinal tubules. Aim: The survey intends to evaluate dentists’ perceptions and understanding of the necessity of preventative endodontic therapy for fixed partial dentures (FPD) in abutment teeth. Setting and Design: Questionnaire-based survey. Methodology: Four hundred people in Tamil Nadu who were among 453 dental professionals, undergrads, and postgraduates responded to an observational study. Analytical Statistics: Multiple linear regression analysis and descriptive statistics were both employed. Results: This survey sheds light on the clinical outcomes that lessen the likelihood of biological failure in FPD patients. Regarding biological failures in abutment teeth for FPDs, among dentists, 21.9% did not experience even one case, 85.6% experienced <5 out of 10 instances, and 11.4% experienced >5 out of 10 cases. Of 400 participants, 52.31% correctly identified deliberate endodontic treatment in abutment teeth for FPDs, while 47.69% gave incorrect responses. Conclusion: Among 400 participants 52.31% have correctly identified deliberate endodontic treatment in abutment teeth for FPDs. 47.69% have given incorrect responses. The survey tried to cover every aspect that should be considered when scheduling elective root canal operations.

Clinical Evaluation of Mandibular Posterior Three-Unit Combined Tooth-/Implant-Supported Fixed Partial Dentures: Controlled Prospective Clinical Study

The aims of the study were to evaluate the clinical performance and the complications of combined tooth-/ implant-supported three-unit fixed partial dentures (FPDs) in the posterior mandible. A total of 78 partially edentulous patients in the posterior mandible were recruited for the study (n = 26/group). Group 1 served as the control group and received two dental implants to support a three-unit FPD. Groups 2 and 3 were the experimental groups in which one implant was placed in conjunction with support from an adjacent tooth to support a three-unit FPD. Standard implants (≥ 8 mm) were included in Group 2, while short implants (< 8 mm) were included in Group 3. Periapical radiographs were taken for evaluation of crestal bone loss (CBL). Modified plaque index (MPI), bleeding index (BI), and sulcus depth values of the abutment teeth were recorded at the time of FPD delivery, 6 months after FPD delivery, and annually thereafter. Recorded complications included abutment tooth intrusions, cementation failures of the restorations, porcelain chipping/delamination, framework fracture, abutment screw loosening, abutment and abutment screw fracture, and implant fracture. Statistically significant differences were observed between Group 1 (0.06 ± 0.17) and Group 2 (0.18 ± 0.32) and between Group 1 and Group 3 (0.17 ± 0.30) in terms of MPI (P ≤ .05). No difference was observed between Group 2 (0.11 ± 0.34) and Group 3 (0.14 ± 0.36) or between Group 1 (0.04 ± 0.22) and Group 2 in terms of BI. There were statistically significant differences in terms of CBL between Group 1 (0.259 ± 0.05 mm) and Group 3 (0.11 ± 0.03 mm) and between Group 2 (0.03 ± 0.03 mm) and Group 3 (P ≤ .05). The mean abutment tooth sulcus depth was 1.11 ± 0.31 mm for Group 2 and 1.20 ± 0.46 mm for Group 3. Within the limitations of the current study, it was concluded that combined tooth/implant-supported prostheses (CTISPs) are a predictable treatment choice in the posterior mandible. When a CTISP is planned, it is more predictable to use a short implant than a standard-length implant.

Application of optical scanning systems and 3D modeling algorithms as a method to control the depth of teeth preparation for fixed orthopedic structures

Background. In orthopedic dentistry at the present stage of its development, a chemical technique for preparing teeth for fixed structures of dentures has been developed; however, the state of the pulp in response to preparation is not taken into account. As a result, medical tactics for preserving or extirpating the pulp of abutment teeth, depending on the clinical case, are unreasonable. Given the generally accepted rules for preparing teeth for fixed orthopedic structures, there is a significant percentage of complications. Controlling the depth of tooth preparation makes it possible to carry out this manipulation as rationally as possible, and as a result to ensure the effectiveness of procedure, based on the state of vitality of the prepared teeth. The aim of the study is to determine and control the depth of the studied teeth preparation using digital volumetric scanning technology and algorithms of a digital graphic 3D editor in the CAD/CAM system. Materials and methods. The article presents the results of using digital volumetric scanning of the CAD/CAM system and an integrated algorithm for digital 3D modeling to determine and control the depth of teeth preparation for fixed orthopedic structures. Results. Based on the results of digital volumetric scanning, the working thickness of the tooth preparation in the area of the tooth neck was determined with the formation of various types of chamfer in different study groups. In order to determine the depth of the preparation of hard dental tissues, an artificial crown was modeled in the CAD system — digital volumetric scanner NeWay (Open Technologies) and data on its thickness in the area of the ledge were obtained. Conclusions. Method of digital volumetric scanning to determine and control the depth of preparation of hard dental tissues makes it possible to prevent the development of irreversible morpho-functional changes in the tissues of teeth caused by odontoreparation.

Accuracy of Computerized Optical Impression Making in Fabrication of Removable Dentures for Partially Edentulous Jaws: An In Vivo Feasibility Study.

The use of computerized optical impression making (COIM) for the fabrication of removable dentures for partially edentulous jaws is a rising trend in dental prosthetics. However, the accuracy of this method compared with that of traditional impression-making techniques remains uncertain. We therefore decided to evaluate the accuracy of COIM in the context of partially edentulous jaws in an in vivo setting. Twelve partially edentulous patients with different Kennedy classes underwent both a conventional impression (CI) and a computerized optical impression (COI) procedure. The CI was then digitized and compared with the COI data using 3D analysis software. Four different comparison situations were assessed: Whole Jaw (WJ), Mucosa with Residual Teeth (M_RT), Isolated Mucosa (IM), and Isolated Abutment Teeth (AT). Statistical analyses were conducted to evaluate group differences by quantifying the deviation values between the CIs and COIs. The mean deviations between the COIs and CIs varied significantly across the different comparison situations, with mucosal areas showing higher deviations than dental hard tissue. However, no statistically significant difference was found between the maxilla and mandible. Although COIM offers a no-pressure impression method that captures surfaces without irritation, it was found to capture mucosa less accurately than dental hard tissue. This discrepancy can likely be attributed to software algorithms that automatically filter out mobile tissues. Clinically, these findings suggest that caution is required when using COIM for prosthetics involving mucosal tissues as deviations could compromise the fit and longevity of the prosthetic appliance. Further research is warranted to assess the clinical relevance of these deviations.

Using the foundation restoration as a blueprint: An uncomplicated approach to retrofitting crowns to existing removable partial dentures using CAD-CAM technology

Removable partial dentures have been used to rehabilitate partially edentulous patients for decades. A challenging but commonly encountered procedure is retrofitting a crown to an existing removable partial denture. Several techniques have been proposed for fabricating these complex prostheses, some involving the intraoral application of polymers to the abutment tooth or making impressions of the preparation with the removable prosthesis seated. The present technique presents an approach that simplifies the design and fabrication of retrofitted crowns for fractured abutment teeth needing foundation restorations. This approach involves the implementation of computer-aided design and computer-aided manufacturing technology to record and utilize the contours of the foundation restoration established intraorally as a blueprint for the retrofitted crown.

Forced Orthodontic Extrusion to Restore the Unrestorable: A Proof of Concept.

The purpose of this clinical study was to assess the feasibility of forced orthodontic extrusion with the Tissue Master Concept to retain subgingivally fractured teeth as abutments for which extraction and replacement would be equal treatment opportunities. Participants were recruited from a group of consecutive patients in need of prosthodontic rehabilitation. In total, 36 deeply destroyed teeth in 31 patients underwent forced orthodontic extrusion with forces exceeding 50 g to reestablish biologic width and ensure a 2-mm dentin-ferrule design prior to single-crown restoration. The primary endpoint was the success of the extrusion in terms of the ability to restore the respective abutment tooth. Information about overall treatment time, frequency, and reasons for failure were collected. Four patients dropped out of the treatment. For the remaining 27 participants, data were fully collected. The amount of extrusion ranged between 2 and 6 mm (3.5 ± 0.9 mm), and the mean duration until retention was 20 ± 12 days. On average, patients returned three (± 3) times for control visits after extrusion. Adhesive failure (n = 6) and orthodontic relapse (n = 2) were the most frequent complication types. Forced orthodontic extrusion may be a useful tool to restore teeth evaluated as nonrestorable.

A Survey of Retention and Support for Anterior Bounded Saddles of Removable Partial Dentures.

The treatment for the anterior bounded saddle because of missing teeth presents several challenges, primarily that of aesthetics. The choice of treatment depends on the position of the saddle, its size, the amount of available alveolar bone support, the health of the abutment teeth, and the patient's wishes.With regard to the use of a removable partial denture (RPD), while acknowledging the significant importance of aesthetics, unless the presence of adequate retention of the prosthesis is ensured, the appearance of the teeth alone will not guarantee its acceptability.This article highlights techniques that are available to provide adequate retention which will, in turn, give a patient confidence with the use of their denture. The techniques described are dependent on laboratory technical knowledge and skills, and on the ability of the patient to manipulate the appliance.

Structurally compromised teeth. Part I: Clinical considerations and novel classification proposal.

A comprehensive classification of structurally compromised teeth (SCT) was introduced. Dental injuries or operative mismanagement undermine the structural integrity of the tooth abutment, reducing its biomechanical strength and rendering restorative procedures challenging. To standardize the overall pre-operative evaluations and determine the biological and mechanical features, a classification of the coronal and cervical tooth defects, as well as an attentive analysis of the most apical location of the residual cervical tooth structure along the whole perimeter and the most coronal location of the bucco/lingual residual structure was presented. Considering the residual cervical structure, five possible clinical scenarios were individuated with respect to the gingival margin, gingival sulcus, supracrestal tissue attachment and bone crest (BC). The latter prevents the isolation procedures rendering the adhesive restorations unfeasible. Instead, the location of the most apical portion of residual cervical structure within subgingival/intrasulcular depth (>1.5 mm above BC) can be considered restorable. This classification is threefold: to enclose all the possible clinically encountered tooth defects, to identify the apical problems of SCT to appropriately manage the perio-restorative interfaces, and to evaluate the tooth resistance capacity of SCT, as to plan and perform the most adequate biomechanical restorative approach. The present classification is proposed to provide a complete perspective of structurally compromised teeth to standardize the biologic and biomechanical evaluations during planning of restorative procedures.

The impact of different polishing systems on yttria-stabilized tetragonal zirconia polycrystalline crowns in relation to heat generation.

To investigate the heat generation on yttria-stabilized tetragonal zirconia polycrystalline (Y-TZP) crowns during polishing with coarse and fine polishing systems at various speeds. Two polishers (coarse and fine) at three polishing speeds were investigated. Two simulation models of the first mandibular molars were prepared for full coverage Y-TZP restorations with different reduction dimensions. Preheated water was pumped into the abutment chamber, to simulate the intrapulpal temperature and blood flow. Twelve Y-TZP crowns (3M™ Lava™ Esthetic) were milled for each prepared tooth abutment and each cusp (n = 10) was individually ground for 30 s and polished for 2 min. Thermocouple wire was secured to the intaglio surface of the crown and linked to a data logger for recording temperature changes. Selected scanning electron microscopy (SEM) images of the treated surfaces and polishers were analyzed. The data was statistically analyzed using Prism 9. The highest temperature rise was observed in the 20,000 RPM polishing speed groups for both coarse and fine polishing, and higher than the threshold value of 5.5°C for pulp damage. The Kruskal-Wallis test, revealed statistically significant differences (p < .0001) in heat generation between low (10,000 RPM) and high (20,000 RPM) polishing speeds. High-speed polishing at 20,000 RPM generated the most heat over the threshold of 5.5°C, which would threaten the dental pulp. The results suggest that a cautionary approach should be taken to high-speed intraoral polishing. Dental clinicians should be aware of the choice of polishing systems and speeds to avoid pulp damage from intraoral polishing of Y-TZP restorations.

Structurally compromised teeth. Part II: A novel approach to peripheral build up procedures.

To introduce the "Peripheral Build-Up technique - PBUt" as a foundation restoration strategy for structurally compromised teeth (SCT). Several strategies have been proposed over time (cervical marginal relocation, doughnut, and preformed ring techniques) to enable the management of restorative procedures in challenging situations such as the presence of deep subgingival defects. The PBUt is a versatile, completely additive direct technique that share some strategical concepts with these techniques to approach critical clinical situations while supplying a wider field of application thanks to distinct operative expedients. The clamp insertion modality, the extension of the proximal wall and the matrix customization/stabilization strategies adopted in PBUt endorse the possibility to manage the most apical and peripheral border of the residual tooth structure when located up to >1.5 mm above the bone crest. The periodontal response has to be then monitored over time. Moreover, thanks to the peripheral and apically-extended addictive approach, it allows a massive preservation of residual sound tooth structure and improves the resistance and retentive physical/geometrical features of the abutment tooth. The PBUt operative workflow is herein explained. The Peripheral-Build-Up technique (PBUt) advocates some innovative clinical restorative steps for the management of SCT with coronal and deep subgingival defects.

Fit and Retention of Cobalt-Chromium Removable Partial Denture Frameworks Fabricated with Selective Laser Melting.

To evaluate fit and retention of cobalt-chromium removable partial denture (RPD) frameworks fabricated with selective laser melting (SLM). Three types of framework for clasp-retained RPDs were virtually designed and fabricated using SLM (n = 30). For comparison, 30 additional frameworks were produced using conventional lost-wax casting. A biomechanical model was created, incorporating extracted teeth mounted on flexible metal posts. Using this model, horizontal constraint forces resulting from a misfit were measured using strain gauges, while vertical forces were not recorded. The constraint force components and resultant forces were determined for all abutment teeth, and the maximum retention force during RPD removal from the model was also assessed. For statistical evaluation, the two fabrication methods were analyzed by calculating the means and standard deviations. The average horizontal constraint forces showed similar values for both fabrication methods (SLM: 3.5 ± 1.0 N, casting: 3.4 ± 1.6 N). The overall scatter of data for cast RPDs was greater compared to those fabricated using SLM, indicating a better reproducibility of the SLM process. With regard to retention, the intended retention force of 5-10 N per abutment tooth was not attained in one of the cast groups, while it was consistently achieved in all SLM groups. This in vitro study found that SLM is a promising option for the manufacture of cobalt-chromium RPD frameworks in terms of fit and retention.

Management of bridge with non-rigid connectors in cases with pier abutments

The type of denture bridge with pier abutments where there are stand-alone abutment teeth between the abutment terminals, requires the dentist to pay special attention. One crown is attached to a natural tooth, and the other crown is attached to a dental implant or other type of abutment, known as the pier abutment that can become a class I fulcrum if restored using a 5-unit bridge with rigid connectors, which can cause excessive force to be received by the retainer at the abutment terminal, leading to debonding of the retainer or even damage to the periodontal tissues of the abutment teeth. In addition to these problems, long-span bridges have a poor prognosis due to the mobility difference between the anterior and posterior teeth, which may cause excessive stress on the connector. The use of a non-rigid connector can overcome this problem, as it can be a stress breaker by allowing micro-movements in the connector. The design of semi-rigid bridge with pier abutments must consider factors such as span length, anticipated occlusal load, and mastication factor. Proper consideration of these factors ensures the safety and longevity of the bridge.

Feasibility of software-based assessment for automated evaluation of tooth preparation for dental crown by using a computational geometric algorithm

The purpose of this study was to propose the concept of software-based automated evaluation (SAE) of tooth preparation quality using computational geometric algorithms, and evaluate the feasibility of SAE in the assessment of abutment tooth preparation for single-unit anatomic contour crowns by comparing it with a human-based digitally assisted evaluation (DAE) by trained human evaluators. Thirty-five mandibular first molars were prepared for anatomical contour crown restoration by graduate students. Each prepared tooth was digitized and evaluated in terms of occlusal reduction and total occlusal convergence using SAE and DAE. Intra-rater agreement for the scores graded by the SAE and DAE and inter-rater agreement between the SAE and DAE were analyzed with the significance level (α) of 0.05. The evaluation using the SAE protocol demonstrated perfect intra-rater agreement, whereas the evaluation using the DAE protocol showed moderate-to-good intra-rater agreement. The evaluation values of the SAE and DAE protocols showed almost perfect inter-rater agreement. The SAE developed for tooth preparation evaluation can be used for dental education and clinical skill feedback. SAE may minimize possible errors in the conventional rating and provide more reliable and precise assessments than the human-based DAE.

Fracture Strength of Composite Rest Seats: An In Vitro Comparative Study of Different Composite versus Amalgam Restorations

Occlusal rest provides support for removable partial dentures (RPD). Rest seats are ideally prepared in enamel, but the abutment teeth might be restored or need restorations. This study compared the fracture strength of abutments restored with composite to amalgam restorations after rest seat preparation. Disto-occlusal cavities were prepared in 30 extracted human maxillary premolars. The specimens were allocated in three groups (n = 10) based on the type of restoration. All the specimens were exposed to thermomechanical aging followed by cycling loading. Fracture strength was tested using a universal testing machine, and then, the fracture mode was recorded. The data were analyzed using Kruskal–Wallis test with a significance level set at 0.05. The fracture mode was recorded as catastrophic or non-catastrophic. The fracture strength between all tested groups showed no significant difference. The highest and lowest fracture strength were recorded on amalgam and Tetric N-Ceram groups, respectively. Composite Tetric N-Ceram showed equal distribution of fracture sites on the restorative materials and teeth, it also displayed the highest number of non-catastrophic fractures unlike other groups where the fracture occurred more within the restorations. The fracture strength of composite was comparable to that of amalgam restorations with prepared rest seats.

In vitro analysis of durability of S-PRG filler-containing composite crowns for primary molar restoration.

To evaluate the reliability, maximum principal stress, shear stress, and crack initiation of a computer-aided design/computer-aided manufacturing (CAD/CAM) resin composite (RC) incorporating surface pre-reacted glass (S-PRG) filler for primary molar teeth. Mandibular primary molar crowns fabricated by experimental (EB) or commercially available CAD/CAM RCs (HC) were prepared and cemented to a resinous abutment tooth using an adhesive resin cement (Cem) or a conventional glass-ionomer cement (CX). These specimens were subjected to a single compressive test (n=5/each) and the step-stress accelerated life testing (SSALT) (n=12/each). Data was evaluated using Weibull analyses and reliability was calculated. Afterwards, the maximum principal stress and crack initiation point of each crown was analyzed by finite element analysis. To evaluate bonding of EB and HC to dentin, microtensile bond strength (μTBS) testing was conducted using primary molar teeth (n=10/each). There was no significant difference between the fracture loads of EB and HC for either cement (p>0.05). The fracture loads of EB-CX and HC-CX were significantly lower than EB-Cem and HC-Cem (p<0.05). The reliability at 600N for EB-Cem was greater than that for EB-CX, HC-Cem, and HC-CX. The maximum principal stress concentrated on EB was lower than that on HC. The shear stress concentrated in the cement layer for EB-CX was higher than that for HC-CX. There was no significant difference among the μTBSs of EB-Cem, EB-CX, HC-Cem, and HC-CX (p>0.05). The crowns fabricated with the experimental CAD/CAM RC incorporating S-PRG filler yielded greater fracture loads and reliability than the crowns manufactured with commercially available CAD/CAM RC regardless of the luting materials. These findings suggest that the experimental CAD/CAM RC crown may be clinically useful for the restoration of primary molars.

Influence of the quality of canal obturation and prosthetic restoration on the peri-apical region

The periapical inflammatory lesion of endodontic origin (LIPOE) is a very common condition and constitutes both a diagnostic and a therapeutic challenge in dentistry. The present study aims to describe the frequency of LIPOE after endodontic treatment consecutive to the quality of root canal fillings and prosthetic restorations of abutment teeth and to identify the qualities of root canal fillings and prosthetic restorations associated with the occurrence of LIPOE. This is a prospective, descriptive and cross-sectional study carried out from March 2019 to August 2022. One hundred and eighty patients wearing Joint Prostheses for at least 2 years with endodontically treated abutment teeth have been recruited; the evaluation of the quality of prosthetic restoration was established according to the criteria of Hickel R while the quality of the root canal filling was judged according to the criteria of Schaeffer MA. The frequency of LIPOE on the abutment teeth was 59.4%. The results highlighted that inadequate quality of prosthetic restoration and root canal filling is associated with the occurrence of LIPOE with a highly significant difference (p˂0.000) In order, to reduce the prevalence of LIPOE and mitigate its effects, it is essential to follow the rules of the art when considering mechanical and biological imperatives during endodontic treatment, as well as good training in prosthetic restoration.

Clinical signs of the quality level of fixed dentures in the process of use and rationale for feasibility of their replacement

The growing requirements for the quality of dental care necessitates expert evaluation of dental prostheses. Therefore, on the way to improve the structure and process of providing dental care, it is important to analyze the primary data of its results in quantitative and qualitative terms. The purpose of this work is to clarify the content and results of consulting care by analyzing clinically important indicators of the quality of fixed dentures that determine their applicability for further use. Among the 410 patients aged 35-81 examined for damage to abutment teeth and periodontal tissues, unsatisfactory condition of crowns and bridges, the 1st subgroup included 76 (18.5%) persons who sought counseling on their own initiative and the 2nd subgroup – 334 (81.5%) persons with referrals from other medical institutions. Quality indicators of 759 artificial crowns and 803 bridges were determined (K08.5 – unsatisfactory restoration of teeth) in the early (up to 24 months) and remote (more than 24 months of use) periods of observation using a modified index of clinical and technological quality. In patients of both groups in the early observation period 67 crowns and 101 bridges (all signs – 253), and in the remote period – 692 crowns and 702 bridges (3804 signs) of low quality were revealed. Quality index of these structures in the early and remote periods of observation was 0,71 versus 0,36 (p&lt;0.05) and 0.64 versus 0.37 respectively (p&lt;0.05). In 71 (93.4%) patients of the 1st group grounds for replacement of 292 out of 327 (89.3%), and in 238 (71.3%) patients of the 2nd group – 827 (67.0%) out of 1235 fixed partial dentures were found. Thus, expert assessment of the quality of dental care is an integral part of ensuring the predicted results of prosthetic treatment. The proposed method of assessing the clinical and technological quality of fixed dentures makes it possible to determine their suitability or unsuitability for further use.

Technical complications with tooth-supported fixed dental prostheses (FDPs) of different span lengths: an up to 15-year retrospective study

BackgroundsLong-span dental bridges may cause excessive load on abutment teeth and the periodontal area, which may lead to bridge fractures or periodontal problems. However, some reports have revealed that short- and long-span bridges can provide a similar prognosis. This clinical study aimed to investigate the technical complications associated with fixed dental prostheses (FDPs) of different span lengths.MethodsAll patients with previously cemented FDPs were clinically examined during their follow-up visits. Several data related to FDPs were registered, such as design, material type, location, and type of complication. The main clinical factors analyzed were technical complications. Life table survival analyses were performed to calculate the cumulative survival rate of FDPs when technical complications were detected.ResultsThe study examined 229 patients with a total number of 258 prostheses and an average of 98 months of follow-up. Seventy-four prostheses suffered from technical complications, and the most common complication was ceramic fracture or chipping (n = 66), while loss of retention occurred in 11 prostheses. The long-term evaluation of long-span prostheses revealed a significantly higher technical complication rate compared to short-span prostheses (P = ,003). The cumulative survival rate for short-span FDPs was 91% in year 5, 68% in year 10, and 34% in year 15. For long-span FDPs, the cumulative survival rate was 85% in year 5, 50% in year 10, and 18% in year 15.ConclusionLong-span prostheses (5 units or more) can be associated with a higher technical complication rate compared to short-span prostheses after long-term evaluation.

Comparison between Distal Extension Attachment-retained Removable Partial Prostheses with Integrated and Conventional Reciprocation Designs: A Clinical Trial.

To compare marginal bone level (MBL) around the abutments in integrated and conventional reciprocation designs in attachment-retained removable partial prosthesis (A-RPP). Around 14 participants were indiscriminately selected and separated into two groups. For every group, an A-RPP with one of the studied reciprocation types was fabricated and assessed. Group I received A-RPP with integrated reciprocation and group II received A-RPP with conventional reciprocation. MBL around the crowned primary and secondary abutments was assessed on the day of A-RPP insertion, at 6 and at 9 months of denture use. Comparison of MBL values at the primary and secondary abutments within each group showed no statistical difference from time of delivery and throughout the study. After using the A-RPP for 6 and 9 months, group I revealed lower mean values of MBL than group II which were statistically significant. Distal extension A-RPP with integrated and conventional reciprocation designs were associated with raise in bone loss. Integrated reciprocation design revealed a lesser amount of bone loss than the conventional reciprocation design and therefore, it is considered as more preferable to be used. Distal extension A-RPP with integrated reciprocation is superior in terms of periodontium preservation around abutment teeth as compared to distal extension A-RPD with conventional reciprocation.

Radiopaque properties of polyetheretherketone crown at laboratory study

ObjectivesThere have been no reports on the radiopaque properties of new polyetheretherketone (PEEK) crowns for locating crowns during accidental ingestion or aspiration and detection of secondary caries, which is essential information for clinical application. This study aimed to investigate whether the radiopaque properties of PEEK crowns could be used to identify the site of accidental ingestion or aspiration and detect secondary caries. MethodsFour types of crowns were fabricated: three non-metal crowns (PEEK, hybrid resin, and zirconia) and one full metal cast crown (gold-silver-palladium alloy). Initially, the images for these crowns were compared using intraoral radiography, chest radiography, cone-beam computed tomography (CBCT), and multi-detector computed tomography (MDCT); computed tomography (CT) values were calculated. Subsequently, the images for the crowns placed on the secondary caries model with two artificial cavities were compared using intraoral radiography. ResultsThe PEEK crowns displayed the lowest radiopaque properties on radiography and very few artifacts were observed on CBCT and MDCT. On the other hand, the CT values of the PEEK crowns were a little lower than those of the hybrid resin crowns and considerably lower than the zirconia and full metal cast crowns. The cavity could be detected in the PEEK crown-placed secondary caries model through intraoral radiography. ConclusionsThis simulated study of radiopaque properties with four types of crowns suggested that a radiographic imaging system can be used to identify the site of accidental ingestion and aspiration of PEEK crowns and to detect secondary caries of the abutment tooth within a PEEK crown.