Effect of different implant locations and abutment types on stress and strain distribution under non-axial loading: A 3-dimensional finite element analysis.

Background/purpose: Dental implants have been a popular treatment for replacing missing teeth. The purpose of this study was to investigate the impact of engaging (hexagonal) and non-engaging (non-hexagonal) abutments in various six-unit fixed prosthesis on the stress distribution and loading located in the implant neck, implant abutment, and surrounding bone. Materials and methods: Three implants were digitally designed and inserted parallel to each other in edentulous sites of the maxillary right canine, maxillary right central incisor, and maxillary left canine. Titanium base engaging abutments, non-engaging abutments and connecting screws were designed. Five distinct models of 6-unit fixed dental prosthesis were created, each featuring different combinations of various abutments. Forces (45-degree angle) were applied to the prosthesis, allowing for the analysis of the stress distribution on the implant neck and abutments, and the maximum and minimum principal stress values on the cortical and trabecular bone. Results: Von Mises stress values and stress distributions located in the implant neck region due to the applied loading forces were analyzed. The overall stress values were highest while employing the hexagonal abutments. The maxillary left canine with a hexagonal abutment (model 5) reported the highest von mises value (64.71 MPa) while the maxillary right canine with a non-hexagonal abutment (model 4) presented lowest von mises value (56.69 MPa). Conclusion: The results suggest that both the various abutment combinations (engaging and non-engaging) on five different models have a similar influence on the distribution of stress within the implant system.

Effects of Surface Treatments and Cement Type on Shear Bond Strength between Titanium Alloy and All-Ceramic Materials.

This study aimed to evaluate the effects of surface treatments and resin cement on the adhesion of ceramic and ceramic-like materials to titanium. A total of 40 specimens (5 mm diameter) of each material (lithium disilicate glass ceramic (LDGC-IPS e.maxCAD), lithium silicate glass ceramic (LSGC-VITA Suprinity) and a polymer-infiltrated ceramic network (PICN-Vita Enamic)) were fabricated using CAD/CAM technologies. In total, 120 titanium (Ti) specimens were divided into 12 groups, and half of the titanium specimens were tribochemically coated using CoJet. The titanium and all-ceramic specimens were cemented using either Self-curing adhesive cement (SCAC-Panavia 21) or a Self-curing luting composite (SCLC-Multilink Hybrid Abutment). After 5000 cycles of thermal aging, the shear bond strength (SBS) test was conducted using a universal testing machine. The failure modes of the specimens were analyzed using stereomicroscopy, and additionally, the representative specimens were observed using Scanning Electron Microscopy. ANOVA was used for the statistical analysis (p < 0.05). The post-hoc Duncan test was used to determine significant differences between the groups. The mean SBS values (mean ± STD) ranged from 15 ± 2 MPa to 29 ± 6 MPa. Significantly higher SBS values were acquired when the titanium surface was tribochemically coated (p < 0.05). The SCLC showed higher SBS values compared to the SCAC. While the LDGC showed the highest SBS values, the PICN presented the lowest. The tribochemical coating on the cementation surfaces of the titanium increased the SBS values. The specimens cemented with the SCLC showed higher SBS values than those with the SCAC. Additionally, the SCLC cement revealed a more significant increase in SBS values when used with the LDGC. The material used for restoration has a high impact on SBS than those of the cement and surface conditioning.

Accuracy of digital impressions for implant-supported complete-arch prosthesis when using an auxiliary geometry device.

Background/purpose: Digital impressions using intraoral scanners have recently gained popularity. The aim of the present study was to evaluate the fit of full-arch screw-retained cobalt-chromium frameworks fabricated via two different digital impression methods. Materials and methods: An edentulous resin master model with four dental implants was fabricated. Forty cobalt-chromium superstructures were fabricated and evaluated according to four groups. In Group 1, the superstructures were evaluated using an intraoral scanner to generate digital impressions. Group 2 relied on the help of an auxiliary geometric appliance in generation of digital impressions via intraoral scanner. The traditional method of splinted open-tray conventional impressions was designated for Group 3. Finally, the control group (Group 4) relied on scanning of the master model directly with a laboratory scanner. Vertical marginal discrepancy was evaluated, and data obtained were statistically analyzed. Results: The highest mean vertical marginal gap value (80.86 ± 50.06 µm) was observed for Group 1 and statistically higher than Group 2, 3, and 4 (P < 0.05). The lowest mean vertical marginal gap value (41.98 ± 26.33 µm) was measured from Group 4 and statistically similar to Group 2 and 3 (P > 0.05). Conclusion: It has been suggested that the use of auxiliary geometric appliances yields increased scanning accuracy. Frameworks fabricated using the traditional splinted open-tray technique were more reliable compared to those frameworks from digital impressions.

Management of Limited Vertical Bone Height in the Posterior Mandible: Short Dental Implants Versus Nerve Lateralization With Standard Length Implants.

Inferior alveolar nerve lateralization (IANL) and short dental implants (SDI) are 2 viable implant-based treatment approaches in the presence of atrophied posterior mandible. Despite the risks of dysfunction, infection, and pathologic fractures in IANL, it becomes possible to place standard implants. The purpose of this study was to compare SDI and IANL approaches from clinical and radiographic aspects. Fifteen subjects having unilateral atrophic mandibles were allocated to SDI and IANL treatment groups. Following surgical procedures, early postoperative complications, implant survival, and periimplant clinical and radiographic parameters including probing pocket depth, attachment level, keratinized tissue amount, vertical tissue recession, and marginal bone loss were recorded at baseline and 1-year after prosthetic rehabilitation. In both groups, no implant was lost. Except usual postoperative complications, 2 patients had transient paraesthesia after IANL. According to time-dependent evaluation, both groups showed significant increase in probing pocket depth and attachment level at 1-year follow-up compared with baseline (P < 0.05). Except a slight but significant increase in mesial surface of SDI group (P < 0.05), no remarkable time-dependent change was identified in vertical tissue recession. Keratinized tissue amount did not exhibit any inter- or intragroup difference during whole study period. Marginal bone loss did not show any difference between IANL and SDI groups at follow-up. SDI placement or standard length implant placement with IANL can be considered promising alternatives in the treatment of atrophic mandibular posterior regions. However, SDI may be preferred in terms of lower complication risk.

Zirconia-based crowns up to 5 years in function: a retrospective clinical study and evaluation of prosthetic restorations and failures.

PURPOSE: The purpose of this retrospective study was to evaluate the 5-year clinical performance and failure rate of single- or multiple-unit zirconia-based crowns. MATERIALS AND METHODS: A total of 148 patients (39 men and 109 women, mean age: 46.9 ± 10.6 years) treated in university and private practices with 618 single- or multiple-unit zirconia-based (Lava) crowns made on natural teeth from January 2007 to December 2008 were included. Two hundred fifty-nine anterior and 359 posterior crowns were examined. A core and/or veneer fracture that required replacement of the restoration was considered to be a failure. The cumulative survival rate (CSR) was described with Kaplan-Meier survival functions. The crowns replaced for other reasons were deemed lost to follow-up, and esthetic, functional, and biologic complications were rated. RESULTS: At the 5-year follow-up, no zirconia core fractures were observed. Twelve veneer fractures that required crown replacement were detected. The CSR was 98.1%. There was a statistically significant difference between survival of the anterior and posterior restorations (P < .001). In total, 116 crowns experienced biologic and technical complications. The most common complications were smooth veneer fracture (4, 0.6%), loss of retention (7, 1%), staining because of smoking (24, 4%), and gingival recession (48, 8%). CONCLUSIONS: According to the 5-year CSR (98.1%) observed in this study, zirconia-based single or multiple crowns may be considered an acceptable treatment modality for the replacement of anterior and posterior teeth. RESULTS from the current study should be supported by additional randomized clinical trials.

A retrospective analysis of the relationship between rhinosinusitis and sinus lift dental implantation.

INTRODUCTION: Dental implants have been associated with the occurrence of postoperative rhinosinusitis. In some patients, preoperative sinus lifting must be performed to increase the chances of successful implant placement. This retrospective study examines the relationship of dental implants after sinus lifting with the occurrence of postoperative rhinosinusitis. METHODS: A total of 268 dental implants were inserted in 94 patients (62 Males, 32 Females) between 2011-2013. The ages ranged from 29-71 (in males) and 33-64 (in females). Additionally, bilateral sinus lifing was performed in 51 patients, and unilateral sinus lifting was performed in 43 of the patients. Patients were evaluated for sinus pathology for a period of 5-47 months postoperatively using a satisfaction questionnaire, conventional radiographic examination, and nasal endoscopic examination. RESULTS: Four of the patients (4.2%) had a complication of postoperative sinusitis and were treated medically. In one patient, the implant was unsuccessful (even after treatment) and was removed. None of the patients needed surgery due to the sinusitis or any associated complications. CONCLUSION: The risk for postoperative rhinosinusitis was found to be higher in patients who suffer from chronic sinusitis and in cases in which a large amount of graft was utilized for sinus lifting. These predisposing factors need to be considered when evaluating patients for dental implants and sinus lift procedures.

Efficiency of pivot splints as jaw exercise apparatus in combination with stabilization splints in anterior disc displacement without reduction: a retrospective study.

OBJECTIVE: To evaluate efficiency of pivot splints in jaw exercises, in combination with stabilization splints, in cases of anterior disc displacement without reduction of temporomandibular joint. SUBJECTS AND METHODS: Twenty-three patients who referred to the prosthodontics clinic in 1995-1997 were included in the study, where anterior disc displacement without reduction of temporomandibular joint was diagnosed using magnetic resonance imaging and clinical examination. Pivot splints were used for jaw exercises for five minutes long; five times/day and stabilization splints were used at all other times. The patients were followed for 24 weeks. Lateral and protrusive excursions along with maximum mouth opening and were evaluated at each control. Bilateral palpation of temporal, masseter, sternocleidomastoid muscles and TMJ was assessed for pain perception before and after treatment. Data were statistically analyzed using Paired sample t-test and Independent Samples t-test (p < .05). RESULTS: Mean mandibular range of motion measurements increased from 28.74 mm prior to 49.17 mm on maximum opening; right/left lateral excursion from 7.61 mm to 12.04 mm and 4.09 mm to 7.3 mm on protrusion after treatment. All changes observed before and after treatment were found to be statistically significant. (p < .001) Pain symptoms were eliminated at the end of 24 weeks of treatment in all patients. CONCLUSION: Using pivot splints as an exercise regimen along with a stabilization splint may be a viable treatment option for patients with anterior disc displacement without reduction; as normal mandibular range of motion was established and pain was eliminated.

Correlation between clinical and magnetic resonance imaging findings in the treatment of anterior disc displacement.

PURPOSE: This study aimed to compare the agreement of clinical examination and magnetic resonance imaging (MRI) results before and after the treatment of nonreduction temporomandibular joint (TMJ) disc displacement. MATERIALS AND METHODS: The study group consisted of 22 patients, each with anterior disc displacement without reduction in at least one TMJ. Diagnosis was performed clinically and with MRI prior to treatment. All patients received the same treatment protocol, consisting of occlusal appliance therapy and exercise for a period of 24 weeks. By the end of treatment, clinical and imaging examinations were repeated and the results subjected to statistical analysis. RESULTS: Before treatment, MRI and clinical examinations matched in 35 of 44 joints (79.5%). On the basis of the kappa index, the agreement between clinical and imaging examinations was moderate (mean kappa index = 0.59, P = .0001). After treatment, these examinations matched in only 16 of 44 cases (36%) and the agreement was poor. CONCLUSION: Clinical criteria do not necessarily correlate with MRI findings in the postoperative period in patients treated for TMJ anterior disc displacement.

Microleakage study of 3 porcelain repair materials by autoradiography.

OBJECTIVE: The purpose of this investigation was to test the microleakage of 3 porcelain repair systems intended for intraoral resin-to-porcelain and resin-to-metal bonding by autoradiography. METHOD AND MATERIALS: Sixty alloy and 60 porcelain disks (10-mm diameter and 2-mm thickness) were prepared. Manufacturer's directions were followed for surface treatment of specimens. Each repair material was applied on 20 alloy specimens and 20 porcelain specimens. Specimens were thermocycled by dipping them in water for 1 minute at 4 +/- 2 degrees C and 58 +/- 2 degrees C for 500 cycles. Leakage was demonstrated by the presence of radioactive isotope at the interface between the repair material and the alloy (or porcelain) as registered by autoradiography. Before testing, specimens were stored in distilled water at 37 degrees C for 24 hours and then thermocycled. Mann-Whitney U test was used to identify the differences. RESULTS: For the alloy groups, differences between Newbond/Clearfil Lustre and GoldLink 2/Ultrabond were significant (P <.05). For the ceramic groups, differences between Cerinate Prime/Ultrabond, Clearfil Lustre/Newbond, Cerinate Prime/Ultrabond, and Silibond/Charizma were significant (P <.05). CONCLUSIONS: For the porcelain groups, the amount of microleakage in Ultrabond/Cerinate Prime was significantly higher than the other groups. For the alloy groups, all samples showed leakage.

Multidisciplinary approach for the treatment of an oblique root fracture: a case report.

This clinical case study describes a multidisciplinary modified technique for the treatment of an oblique root fracture. A-38-year old woman with a history of trauma and a broken tooth was referred to our clinic. There was an oblique crown fracture extending the coronal third of the root just underneath the cingulum of the crown. The patient was willing to keep her tooth in function by any means. Two weeks after root canal therapy the flap was raised. The coronal two third of the root canal was enlarged. An impression of the enlarged root canal and tooth surface with surrounding bone was taken. The flap was sutured and the impression was sent to the laboratory for the post-casting preparation. After 7 days, the flap was opened again and casting was cemented. The flap was sutured. Ten days after the second surgery, three anterior teeth were prepared and a final impression was taken for the preparation of porcelain crowns. Restoration was finished 15 days after the second operation. The patient is still under maintenance therapy and the 12 month results are presented in this report. Extraction may not be the only alternative for the root fractures. Even for fractures under the alveolar margin, alternative multidisciplinary approaches can be used to restore and allow the tooth to survive.

Effect of topical fluorides and citric acid on heat-pressed all-ceramic material.

The effects of citric acid and acidulated phosphate fluoride on the surface roughness of autoglazed and overglazed all-ceramic IPS Empress materials were analyzed. Atomic force microscopy was used to measure the roughness. Citric acid solution (2.00%) was applied for 8 hours, simulating 2 years of exposure. Acidulated phosphate fluoride gel (1.23%) was applied for 32 minutes, simulating 2 years of fluoride therapy. Acidulated phosphate fluoride caused a significant roughening effect on both autoglazed and overglazed specimens.

Non-surgical treatment of sports-related temporomandibular joint disorders in basketball players.

In this study, 18 basketball players (11 female, seven male; age range 14-32 years) with temporomandibular joint (TMJ) problems who had a history of sport injuries related to head or jaw region were evaluated and the results of the treatment were presented. A standardized functional examination of the masticatory system was performed including measurement of maximal jaw movements, recording of joint sounds, pain on movement of the jaw as well as tenderness to palpation of the both TMJ or masticatory muscles. Patients were also evaluated periodontally. Diagnosis was made according the criteria, described by Okeson, and appropriate treatment was applied using different kind of splints. At the end of treatment only one patient continued with right TMJ reduction with slight pain. Except for that patient, none of the patients had pain after treatment. The maximum opening of the jaws and the maximal jaw movements were statistically increased after treatment. Patients with TMJ problems also showed periodontal problems, most likely due to inadequate oral hygiene because of the limited jaw movements and pain. Periodontal parameters including probing depth (PD), Plaque index (PI), and Sulcus Bleeding Index (SBI) improved after treatment. Sports-related TMJ injuries may result in complex problems such as pain, TMJ sounds, limitation in maximal jaw movements and maximum opening of the mouth, difficulty in chewing. With the appropriate diagnosis this could be treated non-surgically in 6-8 months. This study also showed that the TMJ disorders may cause periodontal problems, which may affect all teeth and also the general health of the athlete.

Temporomandibular disorders in Turkish children with mixed and primary dentition: prevalence of signs and symptoms.

The prevalence of signs and symptoms related to TM (temporomandibular) disorders was examined in 40 children with primary dentition and in 40 children with mixed dentition. The purpose of this study was to evaluate the relationship between dentition and TM disorders in the examined population. Maximum mouth opening was also evaluated. Clinical examination was done by one investigator. A questionnaire was used in combination with the clinical examination. The results showed that there was an increase in signs and symptoms from the primary to the mixed dentition group, but only the joint sounds were found significantly different between the two groups. There was no statistically significant difference in maximum mouth opening capacity between the groups.