Canine Region Research Articles

Case report: Dentigerous Cyst and Canine Impaction at the Orbital Floor

Dentigerous cysts are cysts of the epithelial lining of the jaws derived from the dental follicle of unerupted teeth. These cysts are often found during routine radiographic examination along with unerupted teeth. Dentigerous cysts are usually asymptomatic unless the size becomes large, thus causing swelling. This case report describes the management of dentigerous cyst in the upper left canine region with canine impaction to the orbital floor. Dentigerous cyst was treated with cyst enucleation but the impacted canine was not taken because of the magnitude of risk that can occur which was a disruption to the eye muscle. Conclusion. Treatment of dentigerous cysts can be performed by enucleation technique and management related the impacted tooth at the orbital floor needs a further evaluation consideration.

Effect of mucosa thicknesses on stress distribution of implant-supported overdentures under unilateral loading: Photoelastic analysis

The aim of this study was to evaluate the effect of different heights of attachment and mucosa thicknesses on the stress distribution of two implant-retained mandibular overdenture designs under loading using the photoelastic stress analysis method. Six photoelastic models of an edentulous mandibula were fabricated with two solitary implants that were placed in the canine regions. The attachment systems studied were ball and locator stud attachments. Both the ball and locator groups included three models that had different residual ridge heights so as to provide different mucosa thicknesses (1 mm-1 mm, 1 mm-2 mm, 1 mm-4 mm). A static vertical force of 135 N was applied unilaterally (each on the right then the left side) to the central fossa of the first molars. Models were positioned in the field of a circular polariscope to observe the distribution of isochromatic fringes around the implants and the interimplant areas under loading. The photoelastic stress fringes were monitored and recorded photographically. The ball attachment groups showed higher stress values than did the locator groups under loading. Both attachment systems produced the lowest stress values in stimulated 1 mm-1 mm mucosa thickness models. The models with 1 mm-2 mm mucosa thicknesses showed higher stress values than did other models for both attachment systems. The highest stress value observed around both attachment systems was the moderate level in all test models. In different height mucosa thicknesses, locator attachment models distributed the load to the other side of the implant and its surrounding tissue, whereas the ball attachment did not. Regardless of mucosal thickness and attachment type, the implant on the loading side was subjected to the highest stress concentration.

ELECTROMYOGRAPHIC EVALUATION OF IMPLANT OVERDENTURE RETAINED BY TWO DIFFERENT TYPES OF ATTACHMENTS (RANDOMIZED CONTROL TRIAL)

The objective of the present study was to evaluate and compare the influence of two different types of attachments on the masticatory function of complete denture wearers through studying the electromyographic (EMG) activity of the masseter and anterior fibers of temporalis muscles.Material and methods: Fourteen completely edentulous patients with problematic existing mandibular dentures received new conventional complete dentures. Two implants were installed in the mandibular canine regions. After verification of Osseointegration. Patients were randomly divided into two groups by using closed envelope according to the type of attachments used (ball and locator) were installed onto each implant. Electromyographic (EMG) activity of masseter and anterior fibers of temporalis muscles was measured during chewing hard and soft food with conventional dentures before implant placement, one month and three months after implant retained overdentures with the two types of attachments. Data was collected and statistically analyzed.Results: The results obtained from thisstudy revealed a statistically significant increase in the muscles activity after attachment of mandibular dentures onto the implants in the studied groups. The highest activity values were reported for the locator attachment group followed by ball attachment however, the least values were recorded for the conventional complete denture. Nevertheless, the comparison between the two groups at the end of follow up period revealed a statistically insignificant difference .Conclusion: Muscles activity significantly increased after implant treatment. Thus, implant treatment greatly improves oral function. The design of implant attachments did not affect significantly the muscle activity; as no significant differences were observed among the studied attachments (Ball and locator).

Residual setup error in the canine intracranial region after megavoltage, kilovoltage, or cone-beam computed tomographic image guidance for radiation therapy.

Sources of residual setup error after image guidance include image localization accuracy, errors associated with image registration, and inability of some treatment couches to correct submillimeter translational errors and/or pitch and roll errors. The purpose of this experimental study was to measure setup error after image-guided correction of the canine intracranial region, using a four degrees-of-freedom couch capable of 1 mm translational moves. Six cadaver dogs were positioned 45 times as for clinical treatment using a vacuum deformable body cushion, a customizable head cushion, a thermoplastic mask and an indexed maxillary plate with a dental mould. The location of five fiducial markers in the skull bones was compared between the reference position and after megavoltage (MV), kilovoltage (kV) and cone-beam computed tomography (CBCT)-guided correction using orthogonal kV images. The mean three-dimensional distance vectors (3DDV) after MV, kV and CBCT-guided correction were 1.7, 1.5 and 2.2 mm, respectively. All values were significantly different (P < .01). The 95th percentiles of the 3DDV after online MV, kV and CBCT-guided correction were 2.8, 2.6 and 3.6 mm, respectively. Residual setup error in the clinical scenario examined was on the order of millimetres and should be considered when choosing PTV margins for image-guided radiation therapy of the canine intracranial region.

Strains Induced in CAD/CAM Milled Mandibular Implant Retained Overdentures In vivo Strain Gauge Analysis

Purpose: The introduction of computer-aided design/computer-aided manufacturing (CAD/CAM) technology to the field of removable prosthodontics has recently made it possible to fabricate complete dentures using prepolymerized polymethyl methacrylate (PMMA) blocks that are claimed to have better mechanical properties. However, little was published concerning the clinical deformation of CAD/CAM PMMA. The purpose of this study was thus to compare the clinical deformation of CAD/CAM processed PMMA and conventionally processed heat-cured PMMA implant retained mandibular overdenture bases.Materials and Methods: Thoroughly selected ten completely edentulous patients have received two dental implants in the lower canine region. Two duplicate mandibular overdentures were constructed using CAD/CAM milled PMMA and conventionally constructed heat-cured PMMA. Self cure acrylic resin was used to pick up the attachments to the fitting surface of the mandibular overdenture base. Six linear strain gauges were attached to the lingual side of the polished surface of both overdenture bases to measure strains induced during maximal clenching and gum chewing.Results: Higher strain values were recorded with the conventionally constructed heat-cured PMMA overdentures compared to CAD/CAM constructed PMMA overdentures. The recorded strains were mainly compressive at the midline while the strains at implant sites were tensile. Higher strains were recorded during clenching compared to gum chewing in both assessed overdentures. Conclusion: CAD/CAM constructed PMMA implant-retained mandibular overdenture exhibits less denture deformation during function compared to conventionally constructed heat-cured PMMA overdenture.

A three-dimensional finite element stress analysis of two different implant distributions supporting and retaining mandibular overdentures

Statement of Problem: Hinging mandibular overdentures retained by anterior interforaminal implants results in denture rotation and posterior basal bone resorption. Wide spread implant distribution and posterior implant placement can improve overdenture support. Aim of study: To evaluate the biomechanical aspects of novel implant distribution used to support mandibular overdentures and compare it with commonly used design. The novel design consists of mid-symphyseal and bilateral posterior implants in the first molar region as opposed to conventional design with anterior mid-symphyseal and bilateral implants in the canine region.Materials and Methods: Two finite element models were created. In the two models a mid-symphyseal implant was simulated. In the first model (D1), 2 more implants were placed in the canine region bilaterally while for the second model (D2), the 2 additional implants were placed posteriorly in the first molar region. Unilateral vertical and oblique loads were applied on central fossa of right first molar and palatal aspect of central incisors in each model. Von Mises stress distribution was evaluated in the implants and peri-implant bone. Denture displacement was also calculated for each model. Results: There was a slight increase in maximum Von-Mises stress values recorded in both implants and peri-implant bone under both vertical and oblique load in D2 when compared to D1. D1 showed higher denture displacement values when compared to D2. Conclusions: Posterior implant placement resulted in improved denture support and minimal denture displacement on the expense of transferring extra load to the posterior implants. However, increased functional load on posterior implants is expected to have a positive effect on preservation of the residual alveolar ridge. D2 is an acceptable alternative prosthodontic design to D1 when anatomical factor permits.

A Finite Element Study on Comparision of Stress Distribution around the Vertical and Angled Abutments in Implants

Background: Appearance or aesthetics play an important role in the lives of most people specially professionals and any restorations with less than optimal aesthetics will probably not acceptable. Dental implants have earned an excellent reputation for Biocompatibility, Predictability and function throughout the past decades. Use of angulated abutments may be the method of choice when anatomic limitations preclude the axial placement of an implant. A variety of pre angled abutments are available at specific divergence angles, additionally, custom angled abutments may be cast to profile necessary for an acceptable prosthetic outcome. Objectives: The purpose of this study was to evaluate and compare the stress distribution around the vertical (0 degree) and angled (15, 20 degree) abutments in implants. This study was carried out under a vertical force of 100 N and horizontal force of 50 N respectively for all the situations. Materials &amp; Methods: A 3D finite element model was made of anterior maxillary right canine region using the details from the CT scan using the computer software (ANSYS 11). A stimulated 13 × 4.2 mm implant was placed in the centre of the b one and its superstructure was created. Two different loading conditions for 3 different abutment angulations (0, 15, &amp; 20 degree) relative to long axis of implant were applied. The stress generated in the cortical and cancellous bone around the implant was recorded and evaluated with the help of ANSYS. Resuts: It was shown that on vertical loading and horizontal loading of 100 N and 50 N respectively on zero degree angulated abutment, the Von Mises stresses were seen to be uniformly distributed all along the implants in the cortical and cancellous bone. It was also shown that vertical and horizontal loading of 100N and 50 N respectively produced maximum stresses n both cortical and cancellous bone around the neck of Implant for both the 15 degree and 20 degree angulated abutments. Conclusion: the zero degree produced the least amount of stress so as far as possible the Implants should be placed along the axial loading directions of the proposed prosthesis.

Prosthetic Dentistry Possibilities In Patients With Cleft Deformities Of The Palate and Alveolar Ridge

A 56 year old man presented with one-sided cleft palate, affecting alveolar ridge in the upper left canine region. Patient was unable to eat and drink without having the food fall out through his mouths opening into his nose. During first visit, patient underwent x-ray analysis to identify how deeply the bone damage has affected his maxilla. It revealed deep bone penetration, connecting the base of the nose with the mouth. We suggested one of the most effective methods for treating these types of cases – a removable partial denture, which was made to work as an obturator at the same time, closing the space, which causes difficulties to the patient. This case report represents a rare presentation and treatment of cleft palate by using removable partial dentures (RPDs) to close the gap, connecting the patient’s mouth with the nose structures.

Diagnosis and treatment of oral focal mucinosis: a case series

BackgroundOral focal mucinosis, the oral counterpart of cutaneous focal mucinosis, is a rare disease. As it has no characteristic clinical or radiological features, diagnosis is established by histopathological and immunohistological examination. We present three cases of oral focal mucinosis occurring in the retromolar (which is extremely rare) and gingival regions.Case presentationCase 1 involved a 26-year-old Japanese man with radiolucency in the right retromolar region on panoramic radiograph and computed tomography; no obvious protrusion was observed in the region. This finding was clinically diagnosed as a tumor of the retromolar region. Case 2 involved a 60-year-old Japanese woman. A tumor-like mass of tissue was identified on the buccal gingiva at the maxillary right canine and first premolar region. The lesion measured 7 × 6 mm and exhibited elastic hardness and healthy-colored mucosa. The lesion was diagnosed as an epulis. Case 3 involved a 47-year-old Japanese woman. A tumor-like mass of tissue was identified on the buccal gingiva at the maxillary right canine and first premolar region. The lesion measured 10 × 10 mm and exhibited elastic hardness and redness of the surface mucosa. This lesion was also diagnosed as an epulis. Resection was performed in all three cases, and the lesions were histopathologically diagnosed as oral focal mucinosis. Postoperative courses were uneventful and, thus far, there have been no recurrences.ConclusionsAlthough it is difficult to diagnose oral focal mucinosis based on clinical symptoms and imaging findings, the disease should be considered a possibility when diagnosing benign oral tumors. We believe that an emphasis on histopathologic study is essential to confirm the clinical suspicion.

Comparison between the effect of low-level laser therapy and corticotomy-facilitated orthodontics on RANKL release during orthodontic tooth movement: a randomized controlled trial

Bone resorption is the cornerstone in bone remodeling affecting the rate of orthodontic tooth movement. RANKL has a direct effect on osteoclastogenesis. The aim of this study is to evaluate and compare the effect of low-level laser therapy (LLLT) and corticotomy-facilitated orthodontics (CFO) on RANKL release during orthodontic tooth movement. Twenty patients requiring orthodontic therapeutic extraction of the maxillary first premolar were randomly selected. A split-mouth study design was performed where corticotomy-facilitated orthodontics was randomly assigned to one side at the canine region (CG) before retraction, Laser group (LG) was assigned to the contralateral side using 940 nm diode laser irradiations (100 mW, 2.5 J, 3.9 J/cm2) at days 1, 3, 8, and 15. Canine retraction was done using nickel-titanium closed-coil spring applying a force of 150 g per side. Gingival crevicular fluid (GCF) samples were collected from distal surface of the canines on both sides, 1 day before the intervention treatment (T0), day 3 after the intervention (T1), and day 15 (T2). RANKL concentration levels were assessed using enzyme-linked immunosorbent assay. There was statistically significant increase in RANKL concentration levels in both groups (CG and LG) from T0 to T1, there was no statistically significant difference in concentration level from T1 o T2, but there was a statistically significant difference in RANKL concentration levels between T0 and T2 in both groups. CG and LG showed no statistically significant difference in RANKL concentration levels between them in T1 and T2. Low-level laser therapy and corticotomy-facilitated orthodontics can increase the RANKL release during orthodontic tooth movement which directly affects bone remodeling and the rate of orthodontic tooth movement.

Assessment of anterior maxillary alveolar bone dimensions and morphology for immediate implant planning: A retrospective study using Planmeca Promax CBCT unit

Objectives: To evaluate the dimensions and morphology of the alveolar bone in the maxillary central, lateral and canine regions and to correlate these findings with the age and gender of each subject to provide detailed information for immediate implant planning.Subjects & methods: 112 CBCT scans of both genders with non-extracted maxillary right central, lateral and canine were obtained from the database of the Oral and Maxillofacial Radiology Department, Faculty of Dentistry, Cairo University. For each of the three right maxillary anterior teeth bone height was measured from the crest of the ridge till the nasal floor. The bone width was measured at three levels, namely the cervical, the middle and the apical level. The presence and depth of buccal undercuts was also assessed at the three locations. Additionally, the cross-sectional morphology of the alveolar ridge was determined and classified into three different types.Results: The results of this study showed that the bone height at the right central incisor had the least values; meanwhile the canine had the greatest values. Regarding the bone width, the region of the lateral incisor had the thinnest alveolar ridge at the three levels. In all the three locations however, the alveolar width was greater apically than cervically. Besides, the lateral incisor region showed the highest prevalence for presence of buccal undercuts. The greatest depth of buccal undercut however was found in the canine region, meanwhile the smallest depth was found in the central incisor region. For the cross-sectional morphology, Type I (bell-shape) was the most common in all three locations while Type III (hourglass-shape) was the least common. Age did not affect any of the examined parameters. Males showed more height and width of the alveolar bone, while females showed higher prevalence and greater depth of buccal undercuts in all three locations. Males also showed a greater prevalence of Type I (bell-shape) cross-sectional alveolar bone shape, meanwhile females showed a greater prevalence of Type II (trapezoid-shape) and Type III (hourglass-shape).

Huge keratocystic odontogenic tumour in medically compromised patient–a management dilemma

&lt;p class="abstract"&gt;Keratocystic odontogenic tumour (KCOT) is a cystic lesion of the jaws with tumour behaviour. Its high prevalence rate makes it one of the commonest cystic lesions especially involving the lower jaw. The characteristic histologic features and aggressive nature corresponds to the high recurrence rate associated with KCOT. Lesion expands mostly in an anteroposterior direction and can cause extensive bone destruction before the appearance of any clinical symptoms. The characteristic radiological picture is that of a multilocular cystic lesion with the common differential diagnosis being dentigerous cyst and ameloblastoma. Here we are presenting a case of KCOT of the left lower jaw of size 10.9×7.86×8.54 cm. It is a huge multilocular cystic lesion extending from the right canine region to the left side involving the body, ramus, coronoid and condyle. Various management options are there ranging from enucleation and chemical cauterization to resection and reconstruction depending upon the size of the lesion. In this case we were not able to perform the ideal treatment option for the case because of the multiple drug allergy the patient was having, including most of the general anesthetic agents. Also the patient was not willing for any extensive procedure under general anesthesia. So we had to follow a compromised treatment plan aiming to reduce the size of the lesion, to improve the aesthetics and frequent follow up.&lt;/p&gt;

Le Fort I Distraction Osteogenesis of Edentulous Maxillae Combined with Simultaneous Sinus Floor Grafting to Obtain Orthoalveolar Form for Emergence Profile Dental Implant Restorations: Report of Three Patient Treatments Followed for 12Years.

Three edentulous maxillary patients were treated with 9- to 15-mm advances of the maxilla by Le Fort I distraction osteogenesis combined with simultaneous sinus floor autograft placement. The patients were subsequently treated with 8 implants placed in the molar, bicuspid, and canine regions for complete arch ceramo-metal fixed restorations. Anterior emergence profile esthetics was obtained in 2 patients who had high smile lines. Following final restoration, no maxillary relapse was evident, and no implants were lost. Implant bone levels were stable, although 2 implants had 3mm of bone loss over the 12-year follow-up period.

Cone beam computed tomography evaluation of staged lateral ridge augmentation using platelet‐rich fibrin or resorbable collagen membranes in a randomized controlled clinical trial

To evaluate the volumetric changes following lateral alveolar ridge augmentation using autogenous bone graft covered by either a platelet-rich fibrin membrane (test group) or an inorganic bovine bone substitute and a resorbable collagen barrier membrane (control group). A total of 27 partially edentulous patients (test n=14, control n=13) with the indication for lateral bone block augmentation were included in this randomized, controlled clinical trial. Cone beam computed tomography (CBCT) examination was performed prior to grafting and 2weeks and 6months after grafting. The volumetric changes between the various examinations times were evaluated by planimetric measurements on two-dimensional CBCT images of the grafted regions. The mean bone volumetric loss in the test group was 14.7%, SD ±8.9%, while the mean bone volume loss in the control group was 17.8%, SD ±13.3%. This difference was not significant (p=0.48). A total of ten patients were operated in the incisor and canine region with a mean bone volume loss of 23.41% SD, ±10.87%, while 17 patients were operated in the premolar region with a mean bone volume loss of 11.89% SD ±9.05%. This difference was significant (p=0.01). The test and control group demonstrated no overall difference in volumetric bone changes of the augmented bone at the 6-month follow-up. The second major finding revealed a significantly larger amount of bone resorption in the incisor and canine region than in the premolar region of the maxilla, particularly in the control group.

Morphologic Analysis of Maxillary Sinus Floor and its Correlation to Molar Roots using Cone Beam Computed Tomography.

To analyse the anterior extension of the maxillary sinus, distribution of the sinus septa and vertical relationship between the maxillary sinus and molar roots using cone beam computed tomography (CBCT). Imaging data of 970 consecutive patients who underwent CBCT scans were retrospectively collected. The anterior border, septa distribution of the maxillary sinus and relationship between the maxillary sinus and molar roots were analysed. The root-sinus relationship was divided into three types; the roots protruding into the sinus or touching the floor without a bony barrier was defined as Type I root-sinus relationship. Overall, 15.5% of the maxillary sinuses extended beyond the incisor region and 68.9% extended beyond the canine region. A bony septum of ≥ 2 mm was detected in 16.9% (328/1940) of the maxillary sinuses from 26.0% (252/970) of the patients. Among the 355 septa in the 328 sinuses with septa, 108 (30.4%) were located at the first and second premolar region, 180 (50.7%) at the first and second molar region and 67 (18.9%) posterior to the second molar. Among the first molars, a Type I root-sinus relationship was detected in 61.0% of palatine roots, 55.4% of distobuccal (DB) roots, and 52.7% of mesiobuccal (MB) roots. Moreover, among three-rooted second molars, a Type I relationship was detected in 62.0%, 58.2% and 45.8% of MB, DB and palatine roots, respectively. The maxillary sinus can extend beyond the incisor region; approximately 1/6 of sinuses have bony septa; and 1/2 of molar roots protrude into the maxillary sinus or touch the sinus floor without a bony barrier.

New insights in the link between malocclusion and periodontal disease

We aimed to investigate associations between malocclusions and periodontal disease by comparing it to that of smoking in subjects recruited from the population-based cross-sectional study "Study of Health in Pomerania." Sagittal intermaxillary relationship, variables of malocclusion and socio-demographic parameters of 1,202 dentate subjects, 20-39years of age, were selected. Probing depth (PD) and attachment loss (AL) were assessed at four sites by tooth in a half-mouth design. Analyses were performed with multilevel models on subject, jaw and tooth level. Distal occlusion determined in the canine region, ectopic position of canines, anterior spacing, deep anterior overbite and increased sagittal overjet were associated with AL (p-value <0.05). Associations between malocclusions and PD: deep anterior overbite with gingival contact (odds ratio [OR]=1.40, 95% CI: 1.08-1.82; p-value=0.0101) and anterior crossbite (OR=1.75, 95% CI: 1.29-2.38; p-value=0.0003). Regarding crowding, only severe anterior crowding was compatible with a moderate to large association with PD (OR=1.93, 95% CI: 0.89-4.20). Compared to smoking, the overall effect of malocclusions was about one half for AL and one-third for PD. Malocclusions or morphologic parameters were associated with periodontal disease.

Stress distribution around titanium-zirconium narrow-diameter implants retaining mandibular over dentures with Novaloc versus locator attachment systems. A three-dimensional finite element analysis

Statement of the problem: The use of narrow diameter implant to retain an implant overdenture could be the treatment of choice to restore resorbed mandibular ridge, however its success or failure depends on the amount of stresses transferred to the surrounding bone via the selected attachment system. The goal of this study was to evaluate the stress distribution around two narrow- diameter titanium-zirconium implants retaining mandibular overdenture with novel Novaloc attachment system in comparison with traditional locator attachment using 3 D finite element analysisMaterials and methods: Two 3D finite element models were prepared simulating completely edentulous mandibular ridge with complete overdentures supported by two narrow diameter implants in the canine region. Model 1,represented implants with locator attachment while Model 2, represented implants with Novaloc attachment. The models’ components were created on a commercial CAD/CAM package then imported to finite element software. Load of 100 N was applied on molar area of the mandible vertically and oblique Load of 50 N at 30o and 45o angle. Results: Within the limitations of this research, similar deformations and stresses distributions were reported in the bone and implant complex with a little more stresses in the Novaloc system. All values found were within acceptable physiological limits of the studied parts. Stress received by the PEEK matrix of the Novaloc attachment was significantly less than that of the locator nylon cap. Conclusion: Within the limitations of this in-vitro study it may be concluded that locator attachments may provide little less stress on the bone and implant complex in implant retained overdenture than did the Novaloc attachment. However, the lifetime of the flexible caps may be longer for Novaloc system in comparison to locator ones.

Effect of Different Bar Designs on Axial and Nonaxial Retention Forces of Implant-Retained Maxillary Overdentures: An In Vitro Study

This in vitro study aimed to evaluate and compare the effect of different bar designs on the retention forces of implant-retained maxillary overdentures. A maxillary edentulous acrylic resin model without alveolar undercut was fabricated. Four implant analogs were placed in the canine and second premolar regions. Overdentures were made and attached to the analogs with Dolder bar, Hader bar, and milled bar attachments. A universal testing machine was used to measure axial (resistance to vertical displacement) and nonaxial (resistance to anterior, posterior, and lateral displacement) retention forces (in Newtons). Measurements were made at the start of the experiment (initial retention) and after 540 cycles of denture insertion and removal to simulate 6 months of clinical function (final retention). Hader bar had the highest retention after insertions and removals, and Dolder bar had the lowest retention. Vertical displacement showed the highest retention for Dolder and milled bars, and posterior displacement showed the highest retention for Hader bar. Lateral displacement recorded the lowest retention for all bar designs. No significant difference in axial retention loss was observed between different bar designs. Dolder bar showed the highest nonaxial retention loss, and milled bar showed the lowest retention loss. Hader bar is recommended to retain maxillary implant overdentures, as it was associated with higher axial and nonaxial retention compared with Dolder and milled bars after 6 months of simulated denture wear.

Evaluation of the effect of implant angulations and impression techniques on implant cast accuracy - An in vitro study.

Aim:The purpose of this study was to evaluate the accuracy of implant casts generated with splinted and nonsplinted impression techniques with multiple parallel and nonparallel implants.Materials and Methods:In this experimental study, two edentulous maxillary stainless steel models with seven implant analogs in the central incisor, canine, premolar, and first molar region simulating clinical condition were used (control groups). In one master model, implant analogs were placed parallel to each other, whereas in another model, analogs were placed with a tilt-to-longitudinal axis. Forty stone casts were made from each model using splined and nonsplinted technique using polyether with open-tray technique. Then, the difference in the distance between the master cast and experimental cast in three dimensions was measured by coordinate-measuring machine. One-way ANOVA, post hoc Bonferroni test, and unpaired t-test were used for data analysis.Results:Statistical comparisons were made using ANOVA test, post hoc test, and unpaired t-test. Splinted technique with parallel implants generated interimplant distance values closest to the master model, followed by nonsplinted technique with parallel implants, splinted technique with angulated implants, and nonsplinted technique with angulated implants.Conclusions:Splinted impression technique exhibited higher accuracy than the other technique studies in both parallel and angulated implants.

Comparison between all zirconia, all PEEK, and zirconia-PEEK telescopic attachments for two implants retained mandibular complete overdentures: In vitro stress analysis study

Aim: This in vitro study was performed to evaluate and compare stresses applied to the implants retaining mandibular complete overdenture with telescopic attachments of different materials. Materials and Methods: Three identical clear acrylic resin models of completely edentulous mandibular arch were selected for this study. One implant was installed in each canine region of each model. The models were scanned to design telescopic attachment using computer-aided design/computer-aided manufacturing technology. According to material used for telescopic attachments fabrication, models were categorized as follows: All Zirconia (ZrO2) telescopic group (zz): Primary and secondary crowns were made of ZrO2, all polyetheretherketone (PEEK) telescopic group (pp): Primary and secondary crowns were made of PEEK, and Zirconia-PEEK telescopic group (zp): Primary crown was made of ZrO2, and secondary one was made of PEEK. Three identical mandibular complete overdentures were constructed. The secondary telescopic crowns were picked up within the intaglio surface of each overdenture. Four strain gauges were installed parallel to each implant. Bilateral and unilateral loads were applied, and strain values were recorded. Results: Comparison of recorded stresses values revealed a significant difference between groups where the highest stresses were recorded with all-PEEK group, followed by all-zircon group and the lowest stresses were noted with Zirconia-PEEK group for both bilateral and unilateral loading tests. Conclusion: Within the limitation of this in vitro study, it could be concluded that: telescopic attachments that fabricated from ZrO2 primary crown and PEEK secondary crown is a promising attachment regarding reductions of stresses transmitted to the implants retaining mandibular complete overdenture.