Comparison of the accuracy between full-arch digital scans and scannable impression materials: an in vitro study.

BACKGROUND: In some clinical cases, full-arch impression could be difficult to take correctly with the digital way. Patients with high flow salivary rate or with difficulties in mouth opening can still benefit from a conventional impression with elastomer materials that can be directly or indirectly digitized. The aim of this study was to compare the accuracy and precision of two different intraoral scanners (IOSs) and an impression material with scannable properties, by means of three-dimensional analysis of a complete dental arch. METHODS: An anatomical model of complete upper arch, modified with a Scan body placed in the retroincisive area, was used. It was firstly scanned by a desktop scanner to create a digital reference model. Then, 3 groups were created, each constituted by 5 samples. In the first group, 5 impressions were taken from the same master model with the scannable PVS material (Hydrorise Implant), 5 scans were taken using Trios4 (3Shape) and other 5 scans with iTero Element 5D (iTero). STL files obtained from IOSs, and scanned impressions were three-dimensionally superimposed on the STL file of the reference model using the Scan body geometry. RESULTS: The ANOVA Test (P<0.005) did not show any statistically significant difference between the accuracy and precision values of the groups. Each group shows clinically acceptable deviations from the reference model. CONCLUSIONS: Scannable polyvinylsiloxane impression materials are equally accurate and precise as the two IOSs tested in full-arch dentate impressions.

Complete-Arch Accuracy of Four Intraoral Scanners: An In Vitro Study.

The purpose of this study is to define the accuracy of four intraoral scanners (IOS) through the analysis of digital impressions of a complete dental arch model. Eight metal inserts were placed on the model as reference points and then it was scanned with a laboratory scanner in order to obtain the reference model. Subsequently, the reference model was scanned with four IOS (Carestream 3600, CEREC Omnicam, True Definition Scanner, Trios 3Shape). Linear measurements were traced on an STL file between the chosen reference points and divided into four categories: three-element mesiodistal, five-element mesiodistal, diagonal, and contralateral measurements. The digital reference values for the measurements were then compared with the values obtained from the scans to analyze the accuracy of the IOS using ANOVA. There were no statistically significant differences between the measurements of the digital scans obtained with the four IOS systems for any of the measurement groups tested.

Severity of irritable bowel syndrome in patients with temporomandibular disorders: A case-control study.

BACKGROUND: To assess the risk and severity of IBS in a population of TMD patients. MATERIAL AND METHODS: Subjects for the study group were recruited from patients attending the Dental Clinic. Health controls (HC) were recruited among patients' friends and clinic staff. All subjects filled in the RDC/TMD questionnaire and the ROME III questionnaire for the diagnosis of IBS. The IBS Severity Scoring System (IBS-SSS) was used to evaluate the severity of each case of IBS. Categorical variables were compared through the Chi square test. The risk of having abdominal pain was analysed using logistic regression. RESULTS: Twenty-two (46.8%) cases of IBS were diagnosed among TMD patients, whereas only 4 (11.4%) were in the HC group. This difference was statistically significant (χ2(1)=11.6; p<.01). The differences in the distribution of IBS-SSS were statistically significant (χ2(3)=12.49; p<.05). The regression model resulted statistically significant (χ2(5)=24.08; p<.001, R2=.37): abdominal pain was significantly related to nonspecific physical symptoms independent of the other variables. CONCLUSIONS: TMD patients had a greater risk of having IBS compared to HC. TMD patients presented also more severe form of IBS than HC. Key words:Temporomandibular disorders, irritable bowel syndrome, facial pain, case-control study.

In Vitro Fracture Strength of Teeth Restored with Lithium Disilicate Onlays with and without Fiber Post Build-Up.

To our knowledge there is no data about the mechanical performance of indirect restoration adhesively cemented on teeth without an adequate build-up to provide the correct geometrical configuration. The aim of this study was to compare the fracture strength of human teeth restored with lithium disilicate onlays, with and without fiber post build-up. METHODS: Twenty human mandibular molars were horizontally sectioned and divided into two groups (n = 10). No treatment was applied in group A. Teeth in group B were endodontically treated, built-up using fiber post and composite core and prepared with a circumferential chamfer providing a 1 mm circumferential ferrule. Lithium disilicate onlays were pressed and luted on teeth using dual-curing luting composite. Teeth were tested under static load. Failures were classified as restorable or not restorable. Failure loads were analyzed with one-way analysis of variance. Failure modes were compared using Pearson's Chi-square tests. RESULTS: The mean fracture loads were 1383.5 N for group A and 1286.3 N for group B. No difference was found (p = 0.6). Ninety per cent of fractures were classified as not restorable in both groups, with no difference (p = 0.8). CONCLUSIONS: For teeth restored with adhesive procedures and lithium disilicate onlays, the presence of build-up with fiber post to provide retention and resistance form does not influence the fracture strength.

Survival Rates of Lithium Disilicate Single Restorations: A Retrospective Study.

PURPOSE: To assess the clinical performance of lithium disilicate single restorations on natural teeth. MATERIALS AND METHODS: All patients who received lithium disilicate single restorations between 2009 and 2013 at the dental clinic of the University of Ferrara were recalled for clinical evaluation. A total of 43 partial and total restorations in 17 patients were evaluated from a minimum of 36 months follow-up to a maximum of 81 months follow-up, with a mean follow-up of 51 months. RESULTS: The cumulative survival rate was 97.7%, and the cumulative success rate was 94.2%. CONCLUSION: Lithium disilicate can be successfully used for single-tooth restorations.

Effect of flap design and duration of surgery on acute postoperative symptoms and signs after extraction of lower third molars: A randomized prospective study.

Background. Different surgical variables are assumed to play a role in postoperative course after lower third molar extraction. The aim of study was to assess whether flap design and duration of surgery can influence acute postoperative symptoms and signs after lower third molar extraction. Methods. Twenty-five patients scheduled for lower third molar extraction were included in this study and randomly assigned to two groups in terms of flap design: group A (envelope flap) and group B (triangular flap). Swelling and trismus were assessed before and after surgery on days 0, 2 and 7. Pain was assessed for seven days after surgery. Maximum postoperative pain was chosen as the main outcome variable. ANOVA was used to assess differences between the groups regarding maximum postoperative pain, trismus and swelling at 2- and 7-day intervals. Pearson's correlation coefficient was used to assess correlation between duration of surgery and postoperative symptoms and signs. Results. No significant difference was found between the two flap designs for any postoperative symptoms and signs. The duration of surgery was found to be correlated with both trismus (r = -0.44, P = 0.04) and swelling (r = 0.59, P = 0.004) as assessed 2 days after surgery. No associations were found between duration of surgery and maximum postoperative pain and trismus and swelling at 7-day interval. Conclusion. Within the limits of the present study, the duration of surgery, and not the flap design, affected the acute postoperative symptoms and signs after lower third molar extraction.

The use of monolithic lithium disilicate for posterior screw-retained implant crowns.

Lithium disilicate is typically used for fabricating prosthetic crowns to be cemented on teeth or implant abutments. However, its use for producing screw-retained implant crowns has been less commonly described. This report describes the use of monolithic lithium disilicate for a screw-retained implant crowns.

Simplified edentulous treatment: A multicenter randomized controlled trial to evaluate the timing and clinical outcomes of the technique.

STATEMENT OF PROBLEM: The time and cost of conventional complete denture procedures have been questioned in favor of simplified and faster methods. Whether the simplified edentulous treatment (SET) method yields complete dentures with acceptable outcomes is unclear. PURPOSE: The purpose of this randomized clinical trial (RCT) was to evaluate the outcomes of 2 techniques in providing complete dentures: the conventional and the SET methods. MATERIAL AND METHODS: Three Italian academic institutions participated in this single-blind parallel RCT. In total, 64 participants were selected and agreed to join the study. They were allocated randomly to 1 of 2 treatment groups, the conventional and SET group: 32 participants per group, 50% women in each group. Treatment was provided by final year predoctoral dental students. The time required for the clinical and laboratory procedures, the number of clinical sessions, and the laboratory returns were recorded. The clinical quality of the dentures and participant satisfaction were evaluated using questionnaires. Differences between treatment group outcomes were analyzed with 2-tailed independent sample Student t tests for clinical and technical timing and clinical and technical steps and Mann-Whitney U tests for denture quality and participant satisfaction (α=.05). RESULTS: The clinical time required (-34%, P<.001), number of clinical sessions (-34%, P<.001), and laboratory returns (-46.5%, P<.001) were significantly lower for the SET than for the conventional method. The laboratory time required (-10.6%) was not significantly less with the SET method (P=.06). Participant satisfaction (P=.816) and prosthodontist ratings of denture quality (P=.539) were comparable between the groups. The participants appreciated the reduced number of clinical sessions with SET (P=.003). CONCLUSIONS: Simplified edentulous treatment may be considered a reliable method for providing complete dentures in a shorter timeframe while maintaining denture quality and patient satisfaction.

High risk of temporomandibular disorder in irritable bowel syndrome: Is there a correlation with greater illness severity?

AIM: To investigate the prevalence and the risk of temporomandibular disorders (TMDs) in patients with irritable bowel syndrome (IBS) (including each subtype: constipation, diarrhoea, and mixed) compared to the general population. METHODS: Between January 2014 and December 2015 we enrolled consecutively adult patients diagnosed with IBS at the outpatient clinic of the University of Salerno and healthy controls (HC) without IBS. At enrollment, we analyzed all patients for the presence of TMDs according to the Research Diagnostic Criteria for TMD. RESULTS: We enrolled 91 IBS patients (23 IBS-D, 30 IBS-C and 38 IBS-M) and 57 HC in the study. We found a higher risk of having TMD (OR = 3.41, 95%CI: 1.66-7.01) compared to the HC. The risk of having TMD was independent of IBS-subtype. Multiple regression analysis showed that facial pain was positively related to abdominal pain and higher level of depression. CONCLUSION: IBS patients had a more than three times greater risk of TMD compared to HC. The risk of having TMD was similar in different IBS subtypes. IBS patients that also fulfilled criteria for TMD seem to share along with chronic facial and abdominal pain a significant co-occurrence with psychiatric disorders and female preponderance.

Qualitative evaluation of the adesive interface between lithium disilicate, luting composite and natural tooth.

Aim of this work was to qualitatively evaluate the interface between tooth, luting composite and lithium disilicate surface using a scanning electron microscope (SEM). An extracted restoration-free human molar was stored in physiological solution until it was embedded in an autopolimerysing acrylic resin. A standard preparation for overlay was completed and after preparation an anatomic overlay was waxed on the tooth and then hot pressed using lithium disilicate ceramic. After cementation the sample was dissected and the section was analysed using an Automatic Micromet (Remet s.a.s) and the section was analyzed using a scanning electron microscope (SEM). SEM evaluation of the tooth showed the three layers seamlessly; by increasing the enlargement the interface did not change.

Marginal Vertical Fit along the Implant-Abutment Interface: A Microscope Qualitative Analysis.

The aim of this study was to qualitatively evaluate the marginal vertical fit along two different implant-abutment interfaces: (1) a standard abutment on an implant and (2) a computer-aided-design/computer-aided-machine (CAD/CAM) customized screw-retained crown on an implant. Four groups were compared: three customized screw-retained crowns with three different "tolerance" values (CAD-CAM 0, CAD-CAM +1, CAD-CAM -1) and a standard titanium abutment. Qualitative analysis was carried out using an optical microscope. Results showed a vertical gap significantly different from both CAD-CAM 0 and CAD-CAM -1, while no difference was found between standard abutment and CAD-CAM +1. The set tolerance in producing CAD/CAM screw-retained crowns plays a key role in the final fit.

Effect of Different Luting Agents on the Retention of Lithium Disilicate Ceramic Crowns.

No studies are available that evaluate the retention of disilicate crowns according to different cementation procedures. The purpose of this study was to measure the retention of lithium disilicate crowns cemented using two different cementation systems. Twenty extracted mandibular premolars were prepared. Anatomic crowns were waxed and hot pressed using lithium disilicate ceramic. Teeth were divided into two groups (n = 10): (1) self-curing luting composite and (2) glass-ionomer cement (GIC). After cementation, the crowns were embedded in acrylic resin block with a screw base. Each specimen was pulled along the path of insertion in Universal Testing Machine. Failure load in Newtons (N) and failure mode were recorded for each specimen. Failure mode was classified as decementation or fracture. Failure load data were analyzed using one-way analysis of variance (ANOVA). Failure modes were compared using Pearson's Chi-square test. Mean failure load was 306.6(±193.8) N for composite group and 94.7(±48.2) N for GIC group (p = 0.004). Disilicate crown cemented with luting composite most often failed by fracture; otherwise, crown cemented with glass-ionomer cement most often failed by decementation (p = 0.02). Disilicate full crown cemented with luting composite showed higher failure load compared with conventional cementation with glass-ionomer cement.

Effect of fiber post length and bone level on the fracture resistance of endodontically treated teeth.

This study evaluated the combined influence of horizontal bone loss and post length on the fracture resistance of endodontically treated teeth (ETT). Twenty premolars were endodontically treated and divided into four groups of two different post insertion depths (5 and 7 mm) and two alveolar bone levels from cement-enamel junction (2 and 5 mm). After posts (RelyX Fiber Post) were cemented using a self-adhesive resin cement (RelyX Unicem Aplicap) and cores were built up (Filtek Supreme XT Universal Restorative, 3M ESPE, USA), cobalt-chrome copings were luted to each prepared tooth. All specimens were subjected to thermocycling and mechanical loading until fracture occurred. Mean fracture loads (N) were 1,445±342.2 (2 mm bone level/5 mm depth), 1,516±413.4 (2 mm bone level/7 mm depth), 1,736.4±1113.8 (5 mm bone level/5 mm depth), 1,038.6±600.2 (5 mm bone level/7 mm depth). No significant differences were found. Therefore, bone level and post length did not seem to influence the fracture resistance of ETT.

Experimental and numeric stress analysis of titanium and zirconia one-piece dental implants.

PURPOSE: To compare the stress in bone around zirconia and titanium implants under loading. MATERIALS AND METHODS: A one-piece zirconia implant and a replica of the same implant made of commercially pure titanium were embedded in two self-curing acrylic resin blocks. To measure strain, a strain gauge was applied on the surface of the two samples. Loads of 50, 100, and 150 N, with orientations of 30, 45, and 60 degrees with respect to the implant axis were applied on the implant. Strain under all loading conditions on both samples was measured. Three-dimensional virtual replicas of both the implants were reproduced using the finite element method and inserted into a virtual acrylic resin block. All the materials were considered isotropic, linear, and elastic. The same geometry and loading conditions of the experimental setup were used to realize two new models, with the implants embedded within a virtual bone block. RESULTS: Very close values of strain in the two implants embedded in acrylic resin were obtained both experimentally and numerically. The stress states generated by the implants embedded in virtual bone were also very similar, even if the two implants moved differently. Moreover, the stress levels were higher on cortical bone than on trabecular bone. CONCLUSIONS: The stress levels in bone, generated by the two implants, appeared to be very similar. From a mechanical point of view, zirconia is a feasible substitute for titanium.

Explaining pain after lower third molar extraction by preoperative pain assessment.

PURPOSE: To evaluate whether preoperative pain sensitivity testing and emotional perception of pain could explain the level of postoperative pain after lower third molar extraction. PATIENTS AND METHODS: Twenty-three patients (16 women, 7 men) scheduled for lower third molar extraction were enrolled in the study. Patients preoperatively were submitted to a nociceptive stimulus by a cold pressor test (immersion of the hand into ice water). Preoperative pain tolerance (seconds), algosity and unpleasantness (visual analog scale), and dental anxiety (Modified Dental Anxiety Scale) were assessed. The duration of surgery was recorded (minutes). Postoperative pain ratings were taken by self-reported registrations on a 100-mm visual analog scale during the 6 days after surgery. Separate stepwise regression analyses were performed to evaluate the usefulness of preoperative scores in explaining the overall maximum postoperative pain level and postoperative pain rates at different intervals. RESULTS: Preoperative unpleasantness related to the nociceptive stimulus was found to be the best predictor of maximum postoperative pain (adjusted R(2) = 0.39, P = .001). Demographic information (age) and preoperative (dental anxiety, pain tolerance, algosity) and intraoperative (duration of surgery) factors were not correlated with postoperative pain. CONCLUSIONS: These results show that a simple preoperative test is useful to identify patients at risk of developing greater pain after third molar surgery. They are characterized by a higher level of reported pain or unpleasantness after exposure to a nociceptive stimulus. This test may be tailored to specific patient needs for postoperative treatment.

Glenoid fossa osteoma resulting in a progressive malocclusion: a case report.

An osteoma is a benign tumor essentially restricted to the craniofacial skeleton. Osteomas occur most frequently in the frontal, ethmoid, and maxillary sinuses, and rarely affect the glenoid fossa. Osteomas are usually pain-free and remain silent, ie, symptom-free, for many years but may lead to occlusal changes. The report describes the case of an adult man with an osteoma who presented with a chief complaint of malocclusion and who was misdiagnosed. The case points to the diagnostic reasoning necessary to arrive at a correct diagnosis, especially when signs and symptoms, as well as pathology, are rare, eg, not familiar to the clinician.

Milled bar-supported implant overdenture after mandibular resection: a case report.

After surgical treatment for oral cancer, patients often are affected by disfigurements, thwarted function, and psychological and social problems. Prosthodontic rehabilitation has the aim of restoring function and esthetics. Implant-supported prosthodontic rehabilitation is useful for patients with compromised residual ridge anatomy, such as patients with oral cancer following treatment. This clinical report describes the rehabilitation of a patient after mandibular resection with a milled bar-supported implant overdenture. Overdenture achieves best hygienic maintenance, easy soft tissue follow-up, and low realization cost. This rehabilitation increased prosthesis retention and stability and improved oral conditions and the patient's quality of life.

Implant-prosthetic rehabilitation for a patient with monolateral cleft lip and palate: a clinical report.

Cleft lip and palate (CLP) is a malformation of genetic derivation. For patients affected by CLP, procedures of guided bone regeneration by autologous bone grafting are recognized as the most effective to close oronasal communication. The residual gap of alveolar ridge, determined by the absence of 1 or more permanent teeth, can be completed by implant-prosthetic rehabilitation. This kind of rehabilitation for patients with CLP has the aim of completing dental reconstruction by avoiding sacrifice of adjacent teeth and preserving symmetric appearance. This article describes the rehabilitation of an 18-year-old patient affected by right unilateral CLP with use of a titanium implant supporting a single crown to replace the lateral incisor. The technique used was particularly helpful for this cleft case, in which a bone deficit subsisted after secondary bone grafting. An additional bone grafting procedure was performed at the time of implant placement to achieve the best functional and esthetic results.