Nicholas G. Fischer

University of Minnesota Twin Cities | UMN

This report describes a technique integrating facial and dental scanners for treatment planning and execution of a tooth-borne full-mouth reconstruction (FMR) with zirconia fixed prostheses. A partially edentulous female adult presented generalized worn dentition in the incisal and occlusal surfaces. The patient accepted the option for treatment wi...

The purpose of this study was to assess the effects of water storage on the surface microhardness (VHN) and fracture toughness (K1C) of two self-adhesive restorative materials compared to traditional resin composite and resin-modified glass ionomer cement (RMGIC) restorative materials. Methods: Two self-adhesive materials (Activa and Vertise Flow),...

Objective: Peri-implantitis, caused by an inflammatory response to pathogens, is the leading cause of dental implant failure. Poor soft tissue healing surrounding implants - caused by inadequate surface properties - leads to infection, inflammation, and dysregulated keratinocyte and macrophage function. One activated inflammatory response, active...

Previous studies have shown hydrophilic/hydrophobic implant surfaces stimulate/hinder osseointegration. An analogous concept was applied here using common biological functional groups on a model surface to promote oral keratinocytes (OKs) proliferation and hemidesmosomes (HD) to extend implant lifespans through increased soft tissue attachment. How...

Purpose: To evaluate the effect of traditional and conservative endodontic access hole preparation on fracture resistance of chairside computer-aided design and computer-aided manufacturing (CAD-CAM) lithium disilicate maxillary right central incisor crowns. Materials and methods: Fifty-seven milled lithium disilicate maxillary right central inc...

The aim of this in vitro study is to compare the color stability and surface roughness of conventional and self-blending resin composites before and after staining and aging. Three conventional composites (Filtek Z350, IPS Empress Direct, and Estalite Palfique LX5) and one self-blending (Omnichroma) resin composite were used in this study. Sixty di...

The purpose of this study is to compare bond durability, in terms of fatigue bond strength, of a two-step HEMA-free universal adhesive and representative adhesives in each systematic category. The adhesives used in this study were OptiBond FL, Prime&Bond NT, Clearfil SE Bond 2, G2-Bond Universal, and Scotchbond Universal Plus Adhesive. Fatigue bond...

Abstract: Purpose: This study aims to evaluate the effectiveness of two ceramic and two composite polishing systems for a novel chairside computer-aided design/computer-aided manufacturing (CAD/CAM) lithium disilicate ceramic with three-dimensional and two-dimensional microscopy images. This ceramic material can be used for implant-supported or too...

This report describes the importance of and outlines steps for additive wax-up and diagnostic mockup for anterior teeth as diagnostic and driving tools for non-prep and minimally invasive veneer preparations. A 35-year-old male presented to the clinic with the chief complaint of spaces between his front teeth. Diagnostic additive wax-up provided th...

The percutaneous device dilemma describes etiological factors, centered around the disrupted epithelial tissue surrounding non-remodelable devices, that contribute to rampant percutaneous device infection. Natural percutaneous organs, in particular their extracellular matrix mediating the “device”/epithelium interface, serve as exquisite examples t...

Hypodontia is one of the most common developmental problems of human dentition. The treatment of missing maxillary central incisors is always a challenging task, often requiring a multidisciplinary approach. This case report describes such a multidisciplinary approach for a female patient with congenitally missing maxillary central incisors and cla...

It has been well-documented that uncontaminated ground enamel provides the most predictable substrate for the bonding of ceramic veneers, and thus conservative tooth preparation with complete isolation using a rubber dam is key to the long-term success of the restorations presented with five years of follow-up. Rubber dam isolation provides several...

Background Transdermal osseointegrated prosthesis have relatively high infection rates leading to implant revision or failure. A principle cause for this complication is the absence of a durable impervious biomechanical seal at the interface of the hard structure (implant) and adjacent soft tissues. This study explores the possibility of recapitula...

Antimicrobial coatings are one of the most promising strategies to prevent bacterial infections in orthopedic and dental implants. Combining antimicrobial agents with different antimicrobial mechanisms might have synergistic effects and be more potent. Others have shown that nanocomposites of silver nanoparticles (AgNPs) decorated with antimicrobia...

Teeth, long-lasting percutaneous organs, feature soft tissue attachment through adhesive structures, hemidesmosomes, in the junctional epithelium basement membrane adjacent to teeth. This soft tissue attachment prevents bacterial infection of the tooth despite the rich – and harsh –microbial composition of the oral cavity. Conversely, millions of p...

Objectives: The case report describes a minimally invasive, multidisciplinary approach to a single discolored anterior tooth, with internal bleaching using traditional Japanese paper (Washi), a gingivoplasty with a three-dimensional (3D) printed surgical guide, and ultrathin feldspathic porcelain veneers. Clinical consideration: The patient's prim...

Infection in hard tissue regeneration is a clinically-relevant challenge. Development of scaffolds with dual function for promoting bone/dental tissue growth and preventing bacterial infections is a critical need in the field. Here we fabricated hybrid scaffolds by intrafibrillar-mineralization of collagen using a biomimetic process and subsequentl...

Purpose: To evaluate the influence of light irradiation on the clinical efficiency of an in-office whitening agent. Methods: The in-office whitening agent (Opalescence Boost 35%) was used in this study. Two whitening regimens were evaluated on maxillary anterior teeth: (1) with light irradiation; and (2) without light irradiation. The ΔE*, chang...

Abstract Objective: The purpose of this study was to evaluate the effectiveness of five different polishing systems on a computer-aided design and computer-aided manufacturing (CAD/CAM) polymer-infiltrated ceramic-network restoration with nanoscale assessment using atomic force microscopy (AFM) and visual assessment performed by dental school seni...

Functionalization of dental and orthopaedic implants with multiple bioactivities is desirable to obtain surfaces with improved biological performance and reduced infection rates. While many approaches have been explored to date, nearly all functionalized surfaces are static, i.e., non-responsive to biological cues. However, tissue remodeling necess...

Aim and objective: This case report shows how a feldspathic veneer with diagnostic wax-ups, subsequent mock-up, and reduction guides can lead to good patient esthetics and reports a 5-year follow-up. Background: Conservative tooth preparation is important for the long-term success of adhesive dentistry as it has been shown that bonding to enamel...

The salivary pellicle, an adlayer formed by adsorption of salivary components on teeth and dental biomaterials, has direct consequences on basic outcomes of dentistry. Here, we provide an overview of salivary pellicle formation processes with a critical focus on dental biomaterials. We describe and critique the array of salivary pellicle measuremen...

Purpose: To evaluate the ability of a pencil-type transducer connected to a pulser-receiver to measure remaining dentin thickness (RDT). Methods: A total of 24 freshly extracted bovine incisors were used to prepare dentin disks with certain thicknesses (0.5, 1.0, 1.5 and 2.0 mm). The thicknesses of the specimens were measured with an ultrasonic...

Bio-adhesive membranes with controllable and reversible under water adhesion are desirable for several biomedical applications ranging from bio-sensing, drug/ therapeutic delivery and tissue regeneration. Here, we present dual soft mucosal and hard bone/ enamel tissue adhesive nanofiber membranes composed of chitosan and pectin derivatives for pH-c...

Percutaneous devices like orthopedic prosthetic implants for amputees, catheters, and dental implants suffer high infection rates. A critical aspect mediating peri-implant infection of dental implants is lack of a structural barrier between the soft tissue and implant surface which could impede bacteria access and colonization of exposed implant su...

Dental clinicians have relied for centuries on traditional dental materials (polymers, ceramics, metals, and composites) to restore oral health and function to patients. Clinical outcomes for many crucial dental therapies remain poor despite many decades of intense research on these materials. Recent attention has been paid to biomolecules as a cha...

Many chemical routes have been proposed to immobilize peptides on biomedical device surfaces, and in particular, on dental implants to prevent peri-implantitis. While a number of factors affect peptide immobilization quality, an easily controllable factor is the chemistry used to immobilize peptides. These factors affect peptide chemoselectivity, o...

In order to evaluate the influence of 38% silver diamine fluoride (SDF) application on enamel and dentin bond stability of universal adhesives in self‐etch mode, a 38% SDF and three universal adhesives were used in this study. Initial shear bond strength (ISBS), fatigue bond strength (FBS), and shear bond strength of survivors (SBSS) to enamel and...

Objective This study investigated simulated cuspal deflection and flexural properties of bulk-fill and conventional flowable resin composites. Methods and Materials Five bulk-fill and six conventional flowable resin composites were evaluated. Aluminium blocks with a mesio-occlusal-distal cavity were prepared and randomly divided into groups for ea...

Dental materials are susceptible to dental plaque formation, which increases the risk of biofilm-associated oral diseases. Physical-chemical properties of dental material surfaces can affect salivary pellicle formation and bacteria attachment, but relationships between these properties have been understudied. We aimed to assess the effects of surfa...

Esthetic problems in maxillary central incisors are often difficult to treat with dental implants. It is necessary to preserve the interdental papillae, or regenerate them if they are absent, and minimize the risk of loss of hard or soft tissue. This task may be made easier by the recent introduction of ultratranslucent zirconia, which can be used...

Post and core fabrication is important in the restoration of endodontically treated teeth. Significant coronal and radicular dentin destruction commonly occurs in endodontically treated teeth. As a result, preserving all the remaining tooth structure is imperative in order to improve the prognosis of the restorative treatment. Core height and width...

Proliferation is a fundamental cell behavior integral to biomaterial and tissue engineering outcomes. Numerous methods have been developed in order to quantify this relatively complex cell behavior. Measuring proliferation in the context of biomaterials and tissue engineering poses unique challenges. Seemingly trivial factors can affect measurement...

Objective: The combination of partial edentulism and a worn anterior tooth in the esthetic zone can be a challenge for the dentist. This clinical situation requires extensive knowledge of soft and hard tissue management, surgical planning and execution for implant therapy, and conservative tooth preparation with ideal bonding protocols for the too...

Osseointegration (OI) is the direct anchorage of a metal implant into bone, allowing for the connection of an external prosthesis to the skeleton. Osseointegration was first discovered in the 1960's based on the microscopic analysis of titanium implant placed into host bone. New bone was observed to attach directly to the metal surface. Following c...

Purpose: The aim of this study was to investigate simulated localized and generalized wear of indirect composite resins used for implant supported provisional restorations. Materials and methods: The study investigated ten indirect composite resins. Two kinds of wear were simulated by 400,000 cycles in a Leinfelder-Suzuki (Alabama) machine. Loca...

The evolution of bonded restorations has undergone great progress over several decades. Nonetheless, life spans of bonded restorations are limited mainly because of the eventual incidence of recurrent caries. Over time, water and waterborne agents (acids, enzymes) degrade the components of the dentin/restoration interface, allowing bacterial coloni...

Objective: The purpose of this study was to evaluate whether different enamel etching methods with reduced etching times would improve the bonding effectiveness of universal adhesives. Methods and materials: Three enamel etching methods, phosphoric acid ester monomer (PPM) etching, phosphoric acid (PPA) etching, and polyalkenoic acid (PLA) etchi...

The purpose of this study was to: (a) evaluate the role of enamel surface roughness on bond fatigue durability and (b) evaluate statistical differences in roughness values based on measurement technique, including the use of spatial filtering for optical profilometry (OP). OptiBond XTR (Kerr Corp), Prime & Bond elect (DENTSPLY Caulk), Scotchbond Un...

Purpose: To evaluate whether surface moisture would influence the bonding effectiveness of universal adhesives in etch-and-rinse mode. Methods: All-Bond Universal (AB), G-Premio Bond (GP) Prime&Bond Active (PB) and Scotchbond Universal Adhesive (SU) were evaluated. Shear bond strengths after 24 hours and 10,000 thermal cycles of universal adhesi...

The clinical report describes a three-dimensional (3D) printed coping for intraoral evaluation before milling final anterior restorations. The use of printed copings allows restorations for complex and esthetically important restorations to be thoroughly tested at relatively low cost without introducing large delays into the fabrication process.

The purpose of this study was to examine the shear fatigue strengths of a resin composite bonded to dentin. Three adhesive systems – a two‐step self‐etch adhesive (OptiBond XTR; Kerr) and two universal adhesives [Scotchbond Universal (3M ESPE) and G‐Premio Bond (GC)] – were used in self‐etch mode to bond a resin composite to dentin at a physiologic...

Objective: The purpose of this study was to evaluate the effect of reduced application times of universal adhesives on enamel bond fatigue and surface morphology of the treated enamel with constant force atomic force microscopy (AFM). Methods: Four universal adhesives-Adhese Universal (AU), Clearfil Universal Bond Quick (CU), G-Premio Bond (GP),...

Objective: Limited information is available on how to polish and finish zirconia surfaces following computer-aided design/computer-aided manufacturing (CAD/CAM), specifically, how differing application forces and reuse of zirconia polishing systems affect zirconia topography. Purpose: To determine the effect of differing, clinically relevant, po...

The application of resin composites in dentistry has become increasingly widespread due to the increased aesthetic demands of patients, improvements in the formulation of resin composites, and the ability of these materials to bond to tooth structures, together with concerns about dental amalgam fillings. As resistance to wear is an important facto...

Mucosal seal formation around dental abutments is critical to the successful integration of dental implants into the human oral cavity. No information exists for how clinically relevant polishing procedures for computer-aided design and computer-aided manufactured (CAD/CAM) zirconia abutments affects cellular responses important to mucosal seal for...

Purpose: To examine the effect of reduced phosphoric acid pre-etching times on enamel fatigue bond strength of universal adhesives and surface characteristics by using atomic force microscopy (AFM). Materials and methods: Three universal adhesives were used in this study (Clearfil Universal Bond [C], G-Premio Bond [GP], Scotchbond Universal Adhe...