Individual mandibular movement registration and reproduction using an optoeletronic jaw movement analyzer and a dedicated robot: a dental technique.

BACKGROUND: Fully adjustable articulators and pantographs record and reproduce individual mandibular movements. Although these instruments are accurate, they are operator-dependant and time-consuming. Pantographic recording is affected by inter and intra operator variability in the individuation of clinical reference points and afterwards in reading pantographic recording themselves. Finally only border movements can be reproduced. METHODS: Bionic Jaw Motion system is based on two components: a jaw movement analyzer and a robotic device that accurately reproduces recorded movements. The jaw movement analyzer uses an optoelectronic motion system technology made of a high frequency filming camera that acquires 140frames per second and a custom designed software that recognizes and determines the relative distance at each point in time of markers with known geometries connected to each jaw. Circumferential modified retainers connect markers and do not cover any occlusal surfaces neither obstruct occlusion. The recording process takes 5 to 10 s. Mandibular movement performance requires six degrees of freedom of movement, 3 rotations and 3 translations. Other robots are based on the so-called delta mechanics that use several parallel effectors to perform desired movements in order to decompose a complex trajectory into multiple more simple linear movements. However, each parallel effector introduces mechanical inter-component tolerances and mathematical transformations that are required to transform a recorded movement into the combination of movements to be performed by each effector. Bionic Jaw Motion Robot works differently, owing to three motors that perform translational movements and three other motors that perform rotations as a gyroscope. This configuration requires less mechanical components thus reducing mechanical tolerances and production costs. Both the jaw movement analyzer and the robot quantify the movement of the mandible as a rigid body with six degrees of freedom. This represents an additional advantage as no mathematical transformation is needed for the robot to reproduce recorded movements. RESULTS: Based on the described procedure, Bionic Jaw Motion provide accurate recording and reproduction of maxillomandibular relation in static and dynamic conditions. CONCLUSION: This robotic system represents an important advancement compared to available analogical and digital alternatives both in clinical and research contexts for cost reduction, precision and time saving opportunities.

Clinical Assessment of Short Implants Retaining Removable Partial Dentures: 4-year Follow-up.

PURPOSE: To prospectively evaluate the survival at 1 and 4 years of short implants retaining removable partial dentures (RPDs) in Kennedy Class I and II edentulism. MATERIALS AND METHODS: Twenty patients (Kennedy Class I and II) rehabilitated with RPDs were selected for the insertion of one short implant in the distal edentulous ridge, connected to the RPD with a Locator attachment after osseointegration. The following data were recorded at the 1- and 4-year follow-up: bone loss, bleeding on probing (BOP), probing depth (PD), implant mobility, and survival. RESULTS: Thirty-five implants were placed from September 2012 to April 2014. At the 4-year follow-up, 12 implants showed BOP, and for PD, 15 implants showed 2 mm, 16 implants showed 3 mm, and 2 implants showed 4 mm. One implant showed mobility, and two were lost (survival rate: 94.3%; 95% CI: 80.84 to 99.30). The mean bone loss was 1.04 ± 1.88 mm. CONCLUSION: Within the limitations of this study, the implant survival rate and the mean bone loss values reported are comparable with those reported by other authors. The use of short implants for retaining RPDs may be considered a viable treatment option for patients with distal edentulism and contraindications for more complex implant rehabilitation.

Thickness Discrimination Thresholds in Patients Wearing Single-Implant Mandibular Overdentures: 6-Year Follow-up.

PURPOSE: To verify whether single-implant-supported mandibular overdentures improve thickness discrimination. MATERIALS AND METHODS: A selection of edentulous patients treated with single-implant-supported overdentures underwent interocclusal thickness discrimination tests using dedicated metal strips. Fifteen patients were included, and recordings were repeated five times: with complete dentures in place before placement of implants, the day of the prosthetic connection, and 1 month, 1 year, and 6 years after the connection. RESULTS AND CONCLUSION: Thickness discrimination improved at the 1-month recall recording, while after 1 year, it remained stable at low levels.

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.

Transglutaminase 2 May Be Associated with Peri-implant Gingival Overgrowth: Preliminary Assessments.

UNLABELLED: Tissue transglutaminase 2 (TG2) is ubiquitously expressed in normal tissues and plays an important role in the pathophysiology of wound healing. An increase in periodontal tissues has been previously reported in cyclosporine-induced gingival overgrowth. PURPOSE: The aim of this study was to explore associations between TG2 expression and the vascularization and maturation processes of peri-implant soft tissues over time. MATERIALS AND METHODS: Edentulous patients proposed for mandibular implant-retained overdentures were included in the study. Biopsies of the peri-implant mucosa were performed at the first surgical stage and at 4, 8, and 12 months after prosthetic load. A follow-up program was directed to record plaque indexes, bleeding on probing data, and pocket probing depth around implants. An evaluation of the vessels' density was carried out by digital virtual microscopy and using an immunohistochemistry approach (antibodies anti-CD31, anti-TG2). A robust multivariable regression model was implemented. RESULTS: According to model results, blood vessel count and probing (as a marker of gingival overgrowth in absence of plaque) significantly decrease over time and are associated with TG2, particularly for values above the median. CONCLUSION: The association of an increased TG2 expression in the extracellular matrix might have a significant impact in the development of gingival overgrowth around a loaded implant.

Reduction of bacterial adhesion on dental composite resins by silicon-oxygen thin film coatings.

Adhesion of bacteria on dental materials can be reduced by modifying the physical and chemical characteristics of their surfaces, either through the application of specific surface treatments or by the deposition of thin film coatings. Since this approach does not rely on the use of drugs or antimicrobial agents embedded in the materials, its duration is not limited by their possible depletion. Moreover it avoids the risks related to possible cytotoxic effects elicited by antibacterial substances released from the surface and diffused in the surrounding tissues. In this work, the adhesion of Streptococcus mutans and Streptococcus mitis was studied on four composite resins, commonly used for manufacturing dental prostheses. The surfaces of dental materials were modified through the deposition of a-SiO(x) thin films by plasma enhanced chemical vapor deposition. The chemical bonding structure of the coatings was analyzed by Fourier-transform infrared spectroscopy. The morphology of the dental materials before and after the coating deposition was assessed by means of optical microscopy and high-resolution mechanical profilometry, while their wettability was investigated by contact angle measurements. The sample roughness was not altered after coating deposition, while a noticeable increase of wettability was detected for all the samples. Also, the adhesion of S. mitis decreased in a statistically significant way on the coated samples, when compared to the uncoated ones, which did not occur for S. mutans. Within the limitations of this study, a-SiO(x) coatings may affect the adhesion of bacteria such as S. mitis, possibly by changing the wettability of the composite resins investigated.

Simplified edentulous treatment technique for edentulous hemimaxillectomy patients: case history report.

Technical difficulties in the construction of hard palate obturators following oncologic surgery are due to the recording limitations of the entire defect area, plus prosthesis base instability during recording of maxillomandibular relationships. This article describes a time-saving technique that ensures stable and precise recording bases. A light-polymerizing acrylic resin layer is used for making the first impression of the defect, while simultaneously obtaining an acrylic resin impression tray and base for recording maxillomandibular relationships. Adhesive paper copies are used for the arrangement of the anterior teeth.

A novel method for defining and transferring to the laboratory the esthetic data of the edentulous patient: a randomized clinical trial.

PURPOSE: This trial aimed to compare a new technique for defining and transferring the esthetic arrangement to the laboratory with the traditional method. MATERIALS AND METHODS: One hundred twenty-three consecutive edentulous patients were randomly assigned to a case or control group. The case group received arrangement using adhesive paper teeth. The control group received traditional standard care selection and arrangement of anterior teeth. Measured outcomes were the time needed for arrangement and adjustments, patient satisfaction, and number of adjustments at the trial session. RESULTS: Satisfaction and number of adjustments needed were not statistically different in the two groups. The time needed for arranging teeth was statistically less in the case group. CONCLUSION: The technique reduces the time necessary for the esthetic arrangement while maintaining comparable quality of the trial and definitive denture.

Magnet-retained implant-supported overdentures: review and 1-year clinical report.

Open-field aluminum-nickle-cobalt magnets have been used in prosthodontics for many years, but success has been limited because these magnets are susceptible to corrosion by the saliva and because their retentive force is weak relative to the initial retention offered by mechanical attachments. More recently, magnets have been made from alloys of the rare earth elements samarium and neodymium, which provide stronger magnetic force per unit size. In addition, a new generation of laser-welded containers has improved protection from salivary corrosion. The current resurgence of interest in this type of attachment appears justified because, unlike mechanical attachments, magnets have potential for unlimited durability and might therefore be superior to mechanical ball or bar attachments for the retention of removable prostheses on implants. To date, no long-term prospective trials have been conducted to confirm the clinical durability of this new generation of magnets for retaining dentures on either teeth or implants. The aim of this study was to document initial clinical experiences and levels of satisfaction among edentulous patients treated with mandibular implant-supported overdentures retained using a new generation of rare-earth magnetic attachments. At the outset, all but one of the 17 patients had had several years of experience with implant-supported overdentures. During the first year, the mean overall satisfaction among these 17 patients increased from less than 70 to over 90 out of 100 (standardized visual analogue scale). No unusual difficulties were encountered in rendering the treatment or maintaining the attachments. This report offers preliminary evidence of the excellent potential of these magnets for retaining mandibular implant-supported overdentures.

A new clinical method for evaluating the closest speaking space in dentulous and edentulous subjects: a pilot study.

This study proposes a new clinical procedure for measuring the closest speaking space (CSS) and compares it with an instrumental method. The study population included 15 edentulous and 10 dentulous subjects free of systemic disease, speech defects, or masticatory system dysfunction. For all subjects, the CSS was measured using clinical and instrumental methods. The clinical method utilized polyvinyl siloxane, commonly used for interocclusal records, injected on the occlusal surface of the premolars just before the pronunciation of a word containing the consonant sound "s" 3 times. The instrumental method used a kinesiograph. Statistical analysis was performed using 1-way repeated-measures analysis of variance and the Student t test for paired data. There was no statistical difference between the clinical and instrumental methods of determining CSS. Within the limitations of this study, based on a small sample, the new simpler and less expensive method to record the CSS should be considered and further investigated.

A new coping for overdentures. Part 2: Preliminary results of a clinical study.

The aim of this study was to evaluate a new type of coping used for overdentures. Twenty-nine patients received 60 new chairside copings prepared by 3 operators. The copings, used to anchor removable prostheses, were followed up for between 6 months and 4 years with inspection, probing, and radiographic evaluation. Five teeth (8.3%) were extracted. A few clinical problems occurred, including decementation, periodontal pathology (loss of support and bleeding on probing), subgingival decay, and root fracture. No differences were noted in the incidence of complications among the 3 operators. The study demonstrated the clinical predictability of the new copings.

A preliminary in vivo trial of load transfer in mandibular implant-retained overdentures anchored in 2 different ways: allowing and counteracting free rotation.

This in vivo pilot methodologic study used 3 patients to investigate load transfer in mandibular implant-retained overdentures anchored in 2 different ways: allowing (gap condition) and counteracting (contact condition) free rotation. Load cells and strain-gauged abutments were used to evaluate occlusal load, load transmitted to the nonworking-side mucosa, and stress on the working-side abutment, in both contact and gap conditions. The occlusal load was reduced and load was shifted from abutments to mucosa in the gap versus the contact condition. In the contact condition, patients reported more comfort and felt that they could exert greater occlusal force.

Mandibular implant-retained overdentures with 2 different prosthetic designs: a retrospective pilot study on maintenance interventions.

This retrospective study aimed to investigate whether a mandibular implant-retained overdenture designed to counteract the rotation of the denture might influence the clinical outcome, as evaluated through the prosthetic maintenance interventions. The amount of repairs and relines of the mandibular and maxillary dentures required in an experimental group (6 patients wearing an implant-retained overdenture with a metal frame counteracting the rotation) and a control group (6 patients wearing an implant-retained overdenture allowing the rotation) was compared. Both mandibular and maxillary dentures needed few repairs or relines. The 2 types of dentures showed a similar number of maintenance interventions.

MTA obturation of pulpless teeth with open apices: bacterial leakage as detected by polymerase chain reaction assay.

Polymerase chain reaction (PCR) followed by reverse dot blot was used to detect Enterococcus faecalis leakage through mineral trioxide aggregate (MTA) apical obturations of pulpless teeth with open apices. Prepared root canals of 34 extracted teeth were given a standard apical foramen opening and received orthograde apical obturation with MTA; three groups had 1-, 2-, or 3-mm thickness. Sterilized specimens were inoculated with E. faecalis and incubated in sterile medium. DNA extracted from the specimens was amplified by polymerase chain reaction, which yielded a specific segment of E. faecalis 16S rDNA. On day 10 of incubation, no specimens were contaminated. On day 50, almost 17% of specimens were contaminated, with no statistically significant difference between groups (Chi-square = 0.48; df = 2; p = 0.787). Therefore, MTA provides an adequate seal even in cases of orthograde apical obturation of pulpless teeth with open apices.