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Academic Studies



Iatrogenic damage to approximal surfaces in contact with Class II restorations.
Medeiros VA1, Seddon RP.

ABSTRACT: This study investigated the frequency of iatrogenic damage to approximal surfaces in contact with Class II restorations.

METHODS: Patients (n = 28) with a Class II restoration in contact with an unrestored surface had elastic separators fitted interproximally. Contralateral (unrestored) control surfaces were also separated. Impressions (light body polyvinylsiloxane) of the separated surfaces were taken 3-6 days later. Interproximal impressions (28 paired, seven unpaired) were examined by binocular microscope and scanning electron microscope (SEM) for iatrogenic damage, attrition and cavitation due to caries.

RESULTS: 49-60% of surfaces adjacent to Class II restorations had been iatrogenically damaged. The most frequent types of damage were vertical grooves (26%), extensive damage (17%), indentations (6%) and scratches (6%). Damage was more frequent in maxillary teeth (61%) than mandibular teeth (25%), in permanent teeth (60%) more than deciduous teeth (20%). Qualified dentists produced more iatrogenic damage (64%) than undergraduate students (23%).

CONCLUSION: The frequency of iatrogenic damage to approximal surfaces following Class II preparations was 49%, and possibly as much as 60% when questionably damaged surfaces were included. Protection of the adjacent enamel is of paramount importance during Class II cavity preparation.

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Iatrogenic damage to adjacent teeth during classical approximal box preparation.
Lussi A., Gygax M.

ABSTRACT: Cutting and finishing approximal preparations with conventional instrumentation and methods may produce iatrogenic damage in adjacent tooth surfaces which subsequently requires restoration. The objective of this investigation was to determine the occurrence of iatrogenic damage and whether, under everyday working conditions in dental practice, such damage could be reduced significantly by using an alternative method and instrumentation designed especially for the purpose.

METHODS: Dental practitioners were asked to take impressions of teeth scheduled for Class II amalgam restorations. One group (control) prepared the teeth with conventional rotary instrumentation (n = 71), while the test group used a new method and instrumentation (n = 63). These comprised a set of files, a right-angle handpiece with reduced stroke, 36 fixed (rotation-locked) positions for the files and a cylindrical bur with a recessed front-end cutting surface. Damage to the adjacent teeth was assessed under a stereomicroscope.

RESULTS: Using conventional methods, all adjacent tooth surfaces showed damage, often exposing deep layers of dental tissues. There was a clinical and statistically significant reduction of incidence and severity of iatrogenic preparation trauma in the test group.

CONCLUSION: It appears that conventional approximal box preparation results in significant damage to adjacent tooth surfaces. With the system tested, damage to adjacent tooth surfaces during preparation of proximal boxes can be significantly reduced. This should have an impact on the subsequent rate of restoration for the adjacent surfaces.

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Progression of Approximal Caries in Relation to Iatrogenic Preparation Damage
V. Qvist, L. Johannessen & M. Bruun, Journal of Dental Research, 1992

ABSTRACT:  The aim of the present study was to evaluate the effect of iatrogenic preparation damage on the need for operative caries treatment of approximal surfaces, adjacent to Class II amalgam restorations. The material was collected by 77 dentists from the Public Dental Child Health Service in Denmark. It consisted of die-stone models of 187 first-time Class II preparations, adjacent to 190 unfilled approximal surfaces of 58 primary and 132 permanent teeth. The cavity preparations were performed in children between 4 and 17 years of age. They were all filled with amalgam. Information about operative treatment and exfoliation or extraction of the preparation teeth and the adjacent teeth during the following seven years was obtained from the patients' records.

Stereomicroscopic examination of the models revealed preparation damage on 64% of the unfilled approximal surfaces in primary teeth and on 69% of the corresponding test surfaces in permanent teeth. During the observation period, operative treatment was performed on 10% of the undamaged test surfaces in primary teeth and on 35% of the damaged ones (p < 0.05). The corresponding figures for test surfaces in permanent teeth were 6% and 15% (p < 0.05). It is concluded that iatrogenic preparation damage is a frequent side-effect of operative intervention with approximal caries lesions, and represents a dental health problem, since the damage increases caries progression and the perceived need for restorative therapy of the adjacent teeth.

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Minimally Invasive Dentistry--concepts and techniques in cariology.
Ericsson, Kidd, McComb & Noack, Oral health prev. dent, 2003

ABSTRACT: The concept 'Minimally Invasive Dentistry' can be defined as maximal preservation of healthy dental structures. Within cariology, this concept includes the use of all available information and techniques ranging from accurate diagnosis of caries, caries risk assessment and prevention, to technical procedures in repairing restorations. Dentists are currently spending more than half their time replacing old restorations. The main reasons for restoration failures are secondary caries and fractures, factors that are generally not addressed in the technical process of replacing a restoration. Prevailing concepts on minimally invasive dentistry seem to be 'product or technique-motivated', challenging one technique or product with another, rather than focusing on a general concept. New knowledge of caries progression rates has also led to substantial modification of restorative intervention thresholds and further handling of the disease. New diagnostic tools for caries lesion detection, caries risk assessment and focused preventive treatments have decreased the need for early restorative interventions. In parallel to this, new techniques for cutting teeth and removing decay have evolved. This paper focuses on describing minimally invasive dentistry in cariology from a conceptual perspective, relating to clinical caries diagnosis, restorative intervention thresholds and operative procedures, with special reference to survival of tunnel and slot restorations and to repair vs. replacement of defective restorations.

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Proximal Marginal Overhang of Composite Restorations in Relation to Placement Technique of Separation Rings
Loomas, Opdam, Roeters & Huysmans, Operative Dentistry, 2012

ABSTRACT: The aim was to investigate in vitro the marginal overhang in Class II composite restorations placed with various separation rings and placement techniques. A total of 180 Mesial-Occlusal [MO] preparations in artificial molar teeth were divided into nine groups (n=20). After placement of the sectional matrix, one of three ring systems was applied: Contact Matrix System (Danville Materials), Composi-Tight Gold (Garrison), and V-Ring (Triodent). In each group, rings were placed according to four different techniques (V-Ring placed with technique no. 2 only): 1) occlusally of the wedge, 2) on back end of the wedge, 3) between adjacent tooth and wedge, and 4) between treated tooth and wedge. After application of the adhesive resin, preparations were restored with composite Clearfil AP-X (Kuraray) and polymerized in increments. After matrix removal, overhang was measured on a standardized digital macroscopic image in millimeters squared. For analysis, analysis of variance and Tukey B were used (p,0.05). For the Contact Matrix System and Composi-Tight Gold ring, the different placement techniques had a statistically significant effect on the amount of marginal overhang (p,0.031). The V-Ring resulted in the least marginal overhang (p,0.001). None of the placement techniques and separation rings could completely prevent marginal overhang, and the placement technique has a significant influence on its occurrence.

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