Clinical Outcomes of Monolithic Zirconia Crowns on Posterior Natural Abutments Performed by Final Year Dental Medicine Students: A Prospective Study with a 5-Year Follow-Up.

The conventional metal-ceramic is still considered the gold standard in fixed prosthetics especially in terms of longevity. Among alternative materials used, Monolithic Zirconia has shown the capability to reconcile excellent biomechanical properties with acceptable aesthetic performance and to overcome several inconveniences related to veneer restorations. This study aims to clinically evaluate Monolithic Zirconia prosthetic crowns on natural abutments in the posterior sectors, performed by final-year dental medicine students (undoubtedly with less experience in the management of such material) by the standardized California Dental Association score system evaluation, to better understand the viability of Monolithic Zirconia. This prospective study was carried out at the Dental School of the University of Bari "Aldo Moro", Italy. Prosthetic rehabilitation included single crowns or a short pontic prosthesis with maximum one intermediate. Final-year dental students performed tooth reduction under the supervision of three expert tutors. The California Dental Association systematics (based on color, surface, anatomical shape, and marginal integrity) were adopted to evaluate the prosthetic maintenance status over time. Annual follow-up visits were re-evaluated by the same parameters each year. Univariate logistic regression analysis was performed to evaluate outcomes and the Kaplan-Meier plot to report survival. The sample consists of 40 crowns performed on 31 patients, 15 males (48.4%) and 16 females (51.6%) with an average age of 59.3 years. The clinical cases subjected to experimental study were found to be "Excellent" (1a/2a/3a/4a) in 34 cases (85%), "Acceptable" in 4 cases (10%), and "To be re-done" in 2 cases (failures) (5%). Our conclusive data support the predictability of Monolithic Zirconia restorations on natural posterior abutments at a long-term follow-up of five years, even when performed by less-experienced clinicians.

Cranio-Mandibular Disorders after Whiplash Injury: A Mono-Institutional Clinical Study on 31 Patients.

BACKGROUND: Whiplash is a consequence of traumatic injuries, mostly related to road accidents, with variable clinical manifestations, also known as Whiplash Associated Disorders, such as neck, head and temporo-cranio-mandibular pain. METHODS: The current study aims to evaluate the onset and evolution of temporomandibular joint pain in people with whiplash in a study group treated with the use of Zimmer Collars (adjustable rigid cervical collars for neck immobilization), as compared to a control group. This prospective study included 31 patients followed by the Dental Prosthesis Department of the University of Bari "Aldo Moro": 20 patients with whiplash (age range: 20-39 years) treated with Zimmer collars and 11 patients with whiplash (age range: 20-33 years) who were not. Immediately after the whiplash occurred, a visual analogue scale (VAS) was used to describe the intensity of pain and to complete the chart of the European Academy of Craniomandibular Disorders. Five out of twenty patients, already treated with a Zimmer collar, wore an occlusal splint as well because of persistent pain reported at the 28-day and 60-day follow-up and were supported by pharmacological therapy with analgesics (paracetamol) and muscle relaxants (thiocolchicoside). RESULTS: During the last follow-up (at six months), three out of five patients displayed a residual VAS score of 3, 4, and 5, respectively, while the remaining two displayed a VAS of 0. In the control group, four out of eleven patients needed to wear an occlusal splint but without muscle relaxants and analgesics pharmacological therapy; these four corresponded to the patients showing a residual painful symptomatology, with VAS reaching value of 2, and also were the oldest patients of the group. Data regarding VAS values and Zimmer collar use, both at the first visit and six months later, were statistically analyzed. CONCLUSION: Our prospective study highlights how whiplash-associated acute disorders are often self-limiting over a period of few months, thus reducing the possibility of symptom chronicity; the latter seems to be strictly related to lesion severity, pre-existence of a craniomandibular dysfunction and patient age, but appears to be independent from Zimmer collar use, as statistically confirmed.

Improvement of PMMA Dental Matrix Performance by Addition of Titanium Dioxide Nanoparticles and Clay Nanotubes.

Over the last decades, several materials have been proposed for the fabrication of dental and mandibular prosthetic implants. Today, the poly(methyl-methacrylate) (PMMA) resin is the most spread material, due to its ease of processing, low cost, aesthetic properties, low weight, biocompatibility, and biostability in the oral cavity. However, the porous surface (which favors the adhesion of microorganisms) and the weak mechanical properties (which lead to wear or fracture) are the major concerns. The inclusion of engineered nanomaterials in the acrylic matrix could improve the performances of PMMA. In this study, we added two different kind of nanomaterials, namely titanium dioxide nanoparticles (TiO2NPs) and halloysite clay nanotubes (HNTs) at two concentrations (1% and 3% w/w) in PMMA. Then, we assessed the effect of nanomaterials inclusion by the evaluation of specific physical parameters: Young's modulus, roughness, and wettability. In addition, we investigated the potential beneficial effects regarding the Candida albicans (C. albicans) colonization reduction, the most common yeast responsible of several infections in oral cavity. Our experimental results showed an improvement of PMMA performance, following the addition of TiO2NPs and HNTs, in a dose dependent manner. In particular, the presence of TiO2NPs in the methacrylate matrix induced a greater increase in PMMA stiffness respect to HNTs addition. On the other hand, HNTs reduced the rate of C. albicans colonization more significantly than TiO2NPs. The results obtained are of great interest for the improvement of PMMA physico-chemical properties, in view of its possible application in clinical dentistry.

Silver Nanoparticles Addition in Poly(Methyl Methacrylate) Dental Matrix: Topographic and Antimycotic Studies.

The widespread use of nanoparticles (NPs) in medical devices has opened a new scenario in the treatment and prevention of many diseases and infections owing to unique physico-chemical properties of NPs. In this way, silver nanoparticles (AgNPs) are known to have a strong antimicrobial activity, even at low concentrations, due to their ability to selectively destroy cellular membranes. In particular, in the field of dental medicine, the use of AgNPs in different kinds of dental prosthesis matrixes could be a fundamental tool in immunodepressed patients that suffer of different oral infections. Candida albicans (C. albicans), an opportunistic pathogenic yeast with high colonization ability, is one of the causative agents of oral cavity infection. In our work, we added monodispersed citrate-capping AgNPs with a size of 20 nm at two concentrations (3 wt% and 3.5 wt%) in poly(methyl methacrylate) (PMMA), the common resin used to develop dental prostheses. After AgNPs characterization, we evaluated the topographical modification of PMMA and PMMA with the addition of AgNPs by means of atomic force microscopy (AFM), showing the reduction of surface roughness. The C. albicans colonization on PMMA surfaces was assessed by the Miles and Misra technique as well as by scanning electron microscopy (SEM) at 24 h and 48 h with encouraging results on the reduction of yeast viability after AgNPs exposure.