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Statement of Problem: Secondary caries around restorations is a major problem and can be attributed to bacteria invading microgaps formed at the tooth-restoration interface. An antibacterial composite resin containing quaternary ammonium silica (QASi) filler has been reported to inhibit enamel demineralization in situ. However, whether the prevention of enamel demineralization by QASi-containing composite resin is because of the reduced metabolic activity of acid-producing saliva bacteria is unclear., Purpose: The purpose of this study was to compare the effects of QASi-containing composite resin and 2 other restorative materials on the viability of salivary bacteria and sugar-induced acid production., Material and Methods: Whole saliva from each of the 30 study participants, 14 at high risk and 16 at low risk for caries, was brought into contact with quadruplicate specimens of 3 restorative materials, Infinix Flowable Composite, an anti-bacterial composite resin containing 1.5% QASi filler (Nobio), Filtek Supreme Flowable Restorative (3M), a conventional flowable composite resin, and dental amalgam (Silmet). Bacterial growth and sugar-induced acid production on each restorative material were measured every 20 minutes for 18 hours. Caries risk groups were compared using the t test and repeated measures analysis of variance (α=.05). When significant, Bonferroni multiple comparisons were used., Results: On average, the saliva with the QASi-containing composite resin specimens maintained a near-neutral pH, not dropping below pH 6.0. The saliva associated with both conventional restorative materials exhibited a pH drop below 5.5 (P<.001), the critical threshold for tooth demineralization according to the Stephan curve. Virtually no growth was measured on the surface of the antibacterial composite resin, whereas bacteria grew on the conventional composite resin and dental amalgam (P<.001). No differences were observed between participants at high and low risk of caries., Conclusions: Unlike amalgam and conventional composite resin, the QASi-containing composite resin showed a near-complete shutdown of the metabolic activity of salivary bacteria upon contact and virtually no bacterial viability. This suggests that the prevention of tooth demineralization by QASi-containing restoratives is associated with a significant reduction in bacterial metabolic activity., (Copyright © 2023 Editorial Council for The Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

Statement of Problem: Which restorative material is best suited for treating the posterior molar region is unclear. As dentists presumably choose the most appropriate restoration, German dentists were asked how their own molars were treated., Purpose: The purpose of this survey study was to examine molar restorations and their durability in German dentists., Material and Methods: In the official journal of the Federal Dental Association, German dentists were asked to participate in an online survey that gathered demographic data and information on the type and durability of their molar restorations. To reduce selection bias, the data were weighted for region, sex, and age of the dentist., Results: The data set consisted of 1719 molars from 288 dentists. Restorations included gold inlays (25%), composite resin (24.3%), amalgam (11.8%), ceramic inlays (5.4%), glass ionomer cement or compomer (0.8%), gold crowns (21.8%), ceramic crowns (6.6%), and metal-ceramic crowns (4.3%). Notable differences were identified based on the sex, age, and region of the dentist. Women selected increased esthetic options, as did young dentists. Restorations made of gold, amalgam, and base metal had the highest longevity, at more than 20 years CONCLUSIONS: Among German dentists, restorations with metallic materials dominated in molars, with gold accounting for the largest share. In recent years, the proportion of tooth-colored restorations has increased, and in particular, young dentists use composite resin and ceramics., (Copyright © 2020 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

Statement of Problem: Opinions concerning proper restoration of endodontically treated teeth (ETT) vary. A variety of techniques and materials for post-and-core restorations are available. The rationale for post placement performed by German dentists was unknown., Purpose: The purpose of this study was to determine current opinions, applied techniques, and materials for the restoration of ETT in Germany., Material and Methods: A nationwide questionnaire-based survey containing 18 multiple choice questions regarding treatment philosophies, favored post type, and materials for core foundations was mailed to 36,500 German general dentists. A total of 6029 questionnaires (16.5%) were returned. Data were evaluated in terms of the dentists' occupational experience and the frequency of post placement. Descriptive statistics were used to analyze the data., Results: Irrespective of their occupational experience, 52% of the surveyed dentists consider post placement for almost every postendodontic restoration of ETT. The majority of dentists (54%) believe that a post reinforces ETT. Cast posts and cores are used by 55% of all dentists, whereas 34% use prefabricated posts exclusively. Screw posts are the most popular prefabricated post type (47%). Composite resin (51%) is preferred for core foundation, followed by glass ionomer cements (GICs) (26%). Amalgam is seldom used (0.5%). Posts are placed primarily with zinc phosphate cement (51%), followed by GIC (38%)., Conclusion: The treatment philosophy of German dentists is not in complete agreement with recommendations found in the literature. The belief that a post would reinforce an ETT might explain the high frequency of post placements. Due to the partially inconsistent responses, it is difficult to derive a generalized treatment concept.

Statement of Problem: Microleakage is a major factor contributing to the occurrence of secondary caries around amalgam restorations. Purpose The purpose of this study was to evaluate the effect of amalgam type, liner type, and storage period on microleakage., Material and Methods: Two hundred seventy bovine incisors were divided into 18 groups (n = 15). Two high-copper amalgam alloys (admixed and spherical type) and 3 liner options (no liner, varnish, and adhesive) were used to restore Class V preparations. After placement of restorations, the teeth were stored for 3 different periods (1 day, 1 week, and 12 months) in saline solution, After storage, the specimens were immersed in 0.5% methylene blue for 24 hours, sectioned, and then mean depth of dye penetration was measured separately for the incisal and cervical areas with the use of a binocular microscope (x200). Scores were assigned to a millimeter scale (+/- 0.2 mm). The data were analyzed with a 3-way analysis of variance and the Tukey Honestly Significant Different test (alpha = .05)., Results: The 3-way interaction was significant (P < .001 for the cervical and occlusal margins). After short-term storage (1 day and 1 week), the admixed alloy showed significantly lower leakage values than the spherical alloy only in cervical margins (1.45 and 1.56 for the admixed and 1.62 and 1.50 for the spherical alloy at the cervical [P = .034] and incisal margins [P = .702]), respectively. After 12 months, values decreased significantly for both amalgams, which were similar and lower than for the short-term storage period (short-term values of 1.62 and 1.39 for the admixed and 1.69 and 1.46 for the spherical alloy at the cervical and incisal margins, respectively; long-term values of 0.22 and 0.20 for the admixed and 0.33 and 0.36 for the spherical alloy at the cervical and incisal margins, respectively [P < .019]). When the adhesive was used, significantly superior sealing was observed for both amalgams. For the no liner and cavity varnish groups, the admixed alloy showed superior performance compared to the spherical alloy (with no liner, 1.11 and 0.98 for the admixed and 0.83 and 1.08 for the spherical alloy at the cervical and incisal margins, respectively; with varnish, 1.19 and 1.22 for the admixed and 1.63 and 1.34 for the spherical alloy, at the cervical and incisal margins, respectively [P < .037])., Conclusion: In the short-term, the lowest degree of leakage was found when adhesive was used. After 1 year, no differences were detected, regardless of the amalgam type and liner used.

A common dental problem is restoring teeth with gingival or subgingival margins and extensive loss of coronal tooth structure. A technique is presented for doing so by making a wax foundation on the tooth and injecting vinyl polysiloxane impression material around the foundation to form a matrix for the tooth, using rubber dam clamps to stabilize the matrix.

Statement of Problem: The increasing trend toward esthetics has led to controversy as to the longevity of esthetic restorations and the wisdom of having traditional restorations replaced for esthetic reasons. With the assumption that the way dentists treat their own teeth may be a good indication of the accumulated wisdom of the profession, knowledge of dentists' own restorative choices may provide guidance in selecting the most appropriate restorations., Purpose: The purpose of this article was to determine restorative choices of dentists for personal molars and estimate restoration longevity., Material and Methods: Information about dentists' molars was obtained from a Web-based survey designed to receive dentists' demographic data and charting of 8 molar teeth with estimated longevity. Approximately 12,000 e-mails asking to access the website were sent to dentists' addresses randomly selected from a commercial database. Nonrespondents received 1 reminder. The responses were statistically analyzed with a chi-square analysis (alpha=.05)., Results: Seven hundred fifty-seven valid replies provided information for 6,034 teeth (22% unrestored, 75% restored, 2% missing). Restorations reported included amalgam (36%), gold inlay/onlay (13%), complete veneer crown (CVC) (10%), metal-ceramic crown (MCC) (8%), and composite (7%). Other esthetic options accounted for less than 3%. Restorations with more than 20 years longevity included amalgam restorations (58%), gold inlays/onlays (48%) and crowns (23%). Fifty-six percent of esthetic restorations and 5% of amalgams were placed in the last 5 years. The following restorations were placed in the last year (n=186): 38% esthetic, 29% crowns (18% MCC; 11% CVC), and 17% gold inlay/onlay or amalgam. Significant differences (P<.001) were identified for dentist's gender, year of graduation and practice location., Conclusions: Most dentists have not replaced traditional metallic restorations with esthetic alternatives. Dentists still choose nonesthetic options for significant numbers of their own restorations.

A primary consequence of sleep bruxism is severe tooth wear. Although an occlusal splint is able to protect teeth, grinding may continue on its surface. This clinical report describes an approach to restore canine guidance on an occlusal splint, with amalgam, for a patient with sleep bruxism. This procedure allowed maintenance of the canine guidance for a period of time longer than 3 months, postponing the fabrication of a new splint.

The insertion of amalgam through an opening in a matrix band facilitates amalgam condensation, aids moisture control, reduces overhangs, and enables the dentist to achieve an acceptable restoration.

Statement of Problem: Dentin and core materials that substitute for missing dentin are dissimilar materials. A core material with a lower elastic modulus may deform more under applied stress and therefore result in reduced stress concentration at the core/dentin junction., Purpose: This in vitro study examined the effect of core stiffness on the fracture resistance and failure characteristics of a crowned, endodontically treated tooth under simulated occlusal load., Material and Methods: Forty extracted human mandibular premolars were divided equally into 4 groups and prepared for posts and cast crowns as follows: group 1 = cast post and core, cast crown; group 2 = preformed metal post, composite core, and cast crown; group 3 = preformed metal post, amalgam core, and cast crown; and group 4 (control) = preformed metal post, no core, and cast crown. All prepared teeth had 2 mm of sound dentin on which the cemented crown rested. A continuous load (kg) was applied to the buccal cusp at a 30-degree angle to the long axis of each tooth at a crosshead speed of 2 mm/min until failure. Collected data were subjected to 1-way analysis of variance with the Welch modification to compare groups (P<.05)., Results: Failure loads for the 4 test groups were as follows: 98.1 +/- 34.6 kg (group 1), 94.4 +/- 41.8 kg (group 2), 105.5 +/- 18.6 kg (group 3), and 101.1 +/- 55.3 kg (group 4). No significant difference in failure load values was found among the 4 groups. The primary mode of failure (80%) in all groups was an oblique radicular fracture, either apical to the post or at the post level. Horizontal fracture of the root and post was found in groups 1, 2, and 3 (20%). Loosening of the crown, post, and core was found only in group 2(20%)., Conclusion: Within the limitations of this study, core stiffness did not affect the failure resistance of teeth restored with posts and cores and complete-coverage cast metal crowns. The dominant pattern of failure was unrepairable root fracture. Only the composite core exhibited repairable fractures.

Statement of Problem: The use of dentin pins can cause crazing in dentin. Bonding agents represent a more conservative approach to retention but may not ensure a comparable shear bond strength., Purpose: This study compared the shear bond strength of amalgam to dentin with the application of dentin pins, a bonding agent, and a combination of both forms of retention., Material and Methods: Forty-five freshly extracted, intact molar teeth of similar size were ground flat approximately 2 mm coronal to the cemento-enamel junction and then embedded in acrylic resin blocks. The teeth were randomly divided into 3 groups of 15 specimens each. In group 1, Panavia-Ex was applied to exposed dentin surfaces, and the amalgam was condensed with a copper ring. In group 2, two Pinlock dentin pins were placed 3 mm apart; Panavia-Ex was applied to the dentin, and the amalgam was condensed. In group 3, two Pinlock pins were placed 3 mm apart, and the amalgam was condensed. All materials were mixed and applied according to the manufacturers' directions. After the amalgam had set for 10 minutes, the specimens were stored at 37 degrees C for 24 hours, after which they were thermocycled 1500 times at 5 degrees to 55 degrees C with a dwell time of 30 seconds. Specimens then were loaded in shear mode in a universal testing machine at a crosshead speed of 0.5 mm/min until fracture occurred. A 1-way analysis of variance and a Tukey multiple range comparison test were used for statistical analysis (P<.05)., Results: Significant differences were found among all groups. The highest bond strength (181.86 kg/cm(2)) was obtained for group 2 specimens, which were restored with 2 dentin pins and the bonding system tested., Conclusion: Within the limitations of this study, the combined use of dentin pins and Panavia-Ex significantly increased the retention of the amalgam core material.

Statement of Problem: Clinically relevant variables and testing methods have not been used to investigate the effects of core buildup materials on the strength of all-ceramic restorations., Purpose: The aim of this study was to evaluate the compressive strength of Optimal Pressable Ceramic (OPC) all-ceramic crowns supported by 1 of 3 different core materials and subjected to static or cyclic loading in air or water., Material and Methods: A total of 135 human extracted third molar teeth were divided into 3 equal groups, and cores of amalgam, composite, and dentin (control) were fabricated. Complete crown preparations with a circumferential 90 degrees shoulder margin 1 mm deep were prepared to support complete crown restorations. Testing in compression was performed at a loading rate of 2.0 mm/min. Sixty teeth (20 with each type of core) were subjected to static loading, with equal numbers tested in air and water. The remaining 75 teeth (25 with each type of core) were subjected to cyclic loading in water. The compressive and diametral tensile strengths of 6 x 12-mm OPC cylinders also were tested in both air and water. The data were analyzed with 1-way analysis of variance followed by the Tukey multiple means comparison test (P<.05)., Results: Analysis of the static fracture stress of OPC crowns indicated no significant differences among the core materials (values from testing in air and water, respectively: dentin core 22.7 +/- 4.5 MPa and 19.7 +/- 4.7 MPa; amalgam core 25.2 +/- 5.2 MPa and 21.6 +/- 6.3 MPa; and composite core 20.9 +/- 4.1 MPa and 18.7 +/- 4.9 MPa). Under wet conditions, static versus cyclic loading produced significantly different results for each of the core materials (dentin core 19.7 +/- 4.7 MPa vs. 9.5 +/- 1.5 MPa; amalgam core 21.6 +/- 6.3 MPa vs. 10.3 +/- 1.6 MPa; composite core 18.7 +/- 4.9 MPa vs. 13.3 +/- 3.2 MPa). A significant difference was observed for the solid compressive cylinders tested in water (793.8 +/- 280.1 MPa) versus in air (1473.6 +/- 527.4 MPa)., Conclusion: Within the limitations of this study, the mean compressive strength of OPC crowns tested in water was significantly different under cyclic versus static loading. No significant difference among the 3 core materials was found with respect to crown compressive strength.

Statement of Problem: New glass ionomer cements exhibit better mechanical properties than their older counterparts. However, there is concern about their use as a core material in post-and-core applications., Purpose: This in vitro study evaluated the fatigue resistance of 2 new glass ionomer cements, Shofu Hi-Dense and Fuji IX GP, and compared their mechanical behavior as a core material under masticatory load with a silver-reinforced glass ionomer (ESPE Ketac-Silver) and a silver amalgam (Cavex Avaloy LC)., Material and Methods: A total of 100 commercial plastic teeth were divided into 4 groups of 25 specimens each. Titanium posts were placed in the prepared root canals, and cores were built up in amalgam, silver-reinforced glass ionomer cement, and the 2 new glass ionomer cements. The post-and-core specimens were prepared for full cast metal crowns, which were fabricated and cemented with glass ionomer cement. Twenty specimens from each group were placed in a mastication simulator and cyclically loaded with a 400 N force for 1.5 million cycles. The 5 remaining specimens were used as controls. The specimens were sectioned and observed macroscopically and microscopically to determine the number of defects (alterations) in each material. Observed defects were verified with the Kruskal-Wallis test, and the 4 core materials were ranked with the Tukey multiple comparisons test., Results: The mean rank sum values of the defects were as follows: Cavex Avaloy LC Amalgam (16.75), Fuji IX GP (38.50), Shofu Hi-Dense (39.53), and ESPE Ketac-Silver (67.22). The amalgam alloy was significantly different (P< .05) from the others., Conclusion: Under the conditions of this study, the 2 new glass ionomer cements used as core materials showed a higher number of defects than amalgam. These results suggest that their fatigue resistance may be inadequate for post-and-core applications.

Statement of Problem: Determination of the fracture resistance of various restorative materials in Class II approximal slot restorations has not been studied., Purpose: This study evaluated the effects of retention grooves and different restorative materials in Class II approximal slot restorations. To explore the possibilities for further research, the probable effects of preparation size and loading angle were investigated in a limited manner., Material and Methods: Ninety sound, caries-free human maxillary premolars were divided into 9 groups. The cavities were prepared either by hand or in a computer-controlled CNC machine with or without retention grooves. Four were restored with adhesive amalgam, another 4 with composite, and a single group with Compomer resin. The gingival floor depth was 1.5 mm. The specimens were loaded at an angle of 13. 5 degrees to their longitudinal axes by using a computer-controlled material testing machine until failure occurred. For one specific preparation of adhesive amalgam, loading was applied at 0 and 30 degrees to determine the probable effects of the loading angle. For a specific composite, resin application, the effects of the change in gingival floor depth were analyzed by assigning the depth to 2.0 mm., Results: Composite and Compomer resin and composite exhibited better performance than amalgam. The existence of the retention grooves proved to be effective for adhesive amalgam restorations but did not have any advantageous effect in composite and Compomer restoration., Conclusion: For improved fracture resistance in small approximal restorations, the use of composite was the appropriate choice. Compomer also gave satisfactory results. Use of amalgam restoration should be accompanied with retention grooves and an adhesive system to improve its performance.

Statement of Problem: The penetration of oral fluids and bacteria at the interface between the cavity walls and amalgam restorations, which is known as marginal leakage, is one of the problems facing restorative dentistry today. This may cause secondary caries and the irritation of the pulp., Purpose: This in vitro study tested and compared the sealing ability of a cavity varnish and a dental adhesive for decreasing the marginal leakage of high copper amalgam fillings by chemical diffusion technique., Material and Methods: The samples were randomly divided into three groups. The cavities in the first group were filled with high copper amalgam. In the second and third groups, the cavities were treated with Copalite and Panavia EX adhesives, respectively, before the amalgam fillings were performed. After the periods of 2 hours, 48 hours, 1 week, and 1.5 and 6 months, the amount of calcium diffused through the interface area into the deionized water was measured with inductively coupled plasma., Results: Six-month results revealed that using a dental adhesive as an interfacial sealer had significant advantages to reduce microleakage when compared with a conventional copal varnish.

Purpose: This study evaluated the effects of three preparation designs and the influence of an adhesive system in Class II amalgam restorations when a load was applied directly to the marginal ridge., Material and Methods: Seventy-two sound caries-free maxillary molars were divided into 6 groups of 12 teeth. In groups 1 and 4, the preparation had an extension through the occlusal groove, whereas the other four groups used a proximal slot (box-only) preparation. Groups 2 and 5 had facial and lingual retention grooves that extended from the gingival floor to the occlusal surface, and groups 3 and 6 had slots without grooves. Teeth in groups 1, 2, and 3 were restored with amalgam and groups 4, 5, and 6 were restored with resin bonded amalgam. The marginal ridges of the restorations were loaded at an angle of 13.5 degrees to the long axis of the tooth in an Instron testing machine until failure., Results: Analysis of mean failure loads indicated that proximal slot preparations with retention grooves or occlusal extensions were statistically equivalent but significantly greater than proximal slots without grooves. The addition of an adhesive system improved fracture values for all three types of preparations., Conclusions: When proximal caries was diagnosed and no occlusal caries was evident, a proximal slot amalgam restoration combined with retention grooves and an adhesive system was the appropriate choice.

Statement of Problem: Dental amalgam restorations have traditionally been retained in cavity preparations by surgical procedures called retention form. In this procedure healthy dental structure is usually removed to create adequate retention. The increasing use of bonding systems for restorative procedures may result in more conservative cavity preparations., Purpose: The purpose of this study was to evaluate the tensile bond strength of the amalgam to glass ionomer cement under the influence of three adhesive systems (Panavia-EX, Vidrion F fresh mix, and Alpha Seal)., Material and Methods: The bonded assemblies were stored in an environment of 100% relative humidity and 37 degrees C for 24-hour and 30-day storage periods. The test specimen was loaded in tension to failure on a universal testing machine with a crosshead speed of 6 mm/min., Results: The results revealed that in the 24-hour period without acid etch fresh Vidrion F and Panavia Ex adhesives were stronger than autopolymerizing sealant. Panavia Ex adhesive was stronger in the 24-hour period with acid etch., Conclusions: The 30-day period with acid etch revealed no statistical difference among the adhesives. In the 30-day period without acid etch, the fresh Vidrion F adhesive recorded the greatest tensile bond strength.

Purpose: Failures of silver amalgam cores for endodontically treated teeth have been attributed to the use of posts. The use of adhesive agents has been reported to improve the strength of silver amalgam restorations. The purpose of this study was to test the effects of two adhesive agents on the fracture resistance of silver amalgam cores with and without a post., Material and Methods: Sixty mandibular molars were restored with the use of silver amalgam, with or without one of the adhesive agents and/or a tapered prefabricated post. A universal testing machine, with a constant load rate of 0.5 mm/minute, was used to determine the force in kilograms at failure., Results: The use of either adhesive agent with silver amalgam significantly increased the force at failure, and neither adhesive agent was significantly better than the other. Silver amalgam with a post and without an adhesive agent had the least resistance to fracture., Conclusions: The results indicated that endodontically treated mandibular molars restored with silver amalgam are more resistant to fracture when an adhesive agent is used.

A strong durable resin bond to fresh amalgam is desired in composite-veneered amalgam restorations and in adhesive amalgam restorations. The purpose of this study was to evaluate the influence of long-term water storage on the durability of the shear bond strength of new adhesive systems bonded to fresh amalgam. Sixty cylindrical specimens composed of equal parts of amalgam and composite, with a layer of bonding material in between, were prepared for each adhesive system: All-Bond 2, Amalgambond Plus, High-Q. Bond, and Comspan. Specimens were divided into three subgroups and immersed in saline at 37 degrees C for either 48 hours, 3 months, or 6 months. After the immersion period, specimens were thermocycled and subjected to shear bond strength testing. Shear bond strength of Comspan and High-Q-Bond adhesives did not deteriorate significantly during the 6-month experiment and maintained a mostly mixed mode of failure. All-Bond 2 and Amalgambond Plus adhesives exhibited deterioration of the shear bond strength as a function of immersion time and shifted from dominantly mixed mode of failure to totally adhesive (All-Bond 2) or mostly adhesive failure (Amalgambond Plus). Incubation in saline for long periods should be a standard test in evaluating the bond of new adhesive systems to fresh amalgam, whereas short exposure time to water might be misleading.

The purpose of this study was to examine tooth strains in Class II preparations. A Class II cavity was prepared in 16 permanent premolars, and a strain gauge was attached to the buccal surface of each tooth. Each cavity was then restored with bonded amalgam, bonded gallium, composite, or composite with a resin liner. The tooth strains created by these four restorations were determined and evaluated with a strain indicator. The results of this study indicated that composite restorations with and without resin liner created much greater strains to tooth structure than did bonded amalgam and bonded gallium restorations. The application of resin liner before placement of the composite was effective for decreased tooth strain.

Microleakage contributes to deterioration of materials, recurrent decay, growth of microorganisms at the interface, and postoperative tooth sensitivity. This study examined the microleakage between amalgams and tooth surfaces with a cavity liner, a 4-methacryloxyethyl trimellitate anhydride bonding agent (Amalgambond) and six different types of amalgams. Class 1 cavity preparations in extracted human molars were filled with different combinations of liners and amalgams and were stored at 37 degrees C in physiologic saline solution. After 1 week half of each amalgam restoration was removed. Within the same group the same cavity treatment was performed and the same type of amalgam was packed as before. Microleakage was determined after 2000 thermal cycles. Statistical analysis indicated that Amalgambond significantly reduced microleakage of different amalgams compared with the Copalite-lined and unlined controls. No microleakage was detected at the interface between the existing and replacement amalgams.

Post designs may have a direct effect on fracture resistance of endodontically treated teeth. This in vitro study compared the resistance of three prefabricated threaded post systems with lateral shearing forces. After endodontics were completed, prefabricated posts were inserted according to the manufacturer's instructions. A silver amalgam core was placed, and extracted human teeth were prepared to a standard size with a 1 mm gingival chamfer finished on sound dentino A cast was fabricated and cemented, and the specimens were thermocycled. The test samples were secured to an Instron testing machine and loaded until failure. Fracture patterns were recorded, fractured surface areas were measured, and compressive stresses were calculated. However, there were no statistically significant differences among threaded posts in each test group.

This study compared the shear bond strength of resin-bonded amalgam with and without pins. The coronal third of 240 embedded posterior teeth was removed to expose a flat, nonretentive surface. Three Minikin pins were placed in the dentin in a triangular pattern 1 mm apart. Amalgam was condensed into a Delrin mold (4.2 mm in diameter and 3 mm in height) positioned over each tooth. The adhesives Amalgam-bond, All-bond, Amalgambond with high-performance additive, Panavia EX, and Panavia with Photobond were the materials used to bond the amalgam to the dentin. Half of the samples were immersed in normal saline solution for 7 days and the others for 30 days. Shear bond strengths were recorded as the maximum load per cross-sectional area of the bonded surface with a testing machine with 1 kN load cell and crosshead speed of 0.5 mm/min. A three-factor analysis of variance and Student-Newman-Keuls test (p = 0.05) identified Amalgambond with high-performance additive as the strongest adhesive in this study. The use of pins with or without adhesives increased the shear strength of amalgam samples significantly more than samples that used adhesives alone.

Class V cavities present special problems in restoration and maintenance. The subsequent health of the gingival tissue and the relative immunity toward recurrent caries depends not only on the age of the patient and patient's oral hygiene but to a great extent on the excellence of the restoration. This excellence is achieved by the operator's detailed design of the preparation, moisture control, and restoration and material finishing. Dental amalgam continues to be the material of choice in many clinical situations. The restoration of a large class V lesion that results from replacement of a defective restoration or extensive caries benefits greatly when a copper band matrix is used because of its ability to be shaped and contoured and its rigidity. In large class V cavities, the copper band creates a "false" wall that is required for confinement of the amalgam as it must be packed under pressure. This confinement of the cavity is necessary because it restricts the amount of excess material which ultimately is important in the restoration of the tooth and its long-term success.

Secondary caries is one of the greatest causes for replacement of amalgam restorations. This study verified whether marginal defects in class I restorations could be a determining factor in the development of secondary caries. Fifty-five extracted premolars and molars whose occlusal surfaces were already restored with amalgam were selected. A macroscopic examination of these teeth was carried out to see whether there was a difference in the prevalence of caries beneath ditched and nonditched margins. To assess the presence of caries, a section was ground in each tooth so that the cut passed through a ditched margin and a better margin. This permitted assessment of the two types of margins that had been exposed to the same oral environment. Macroscopic examination revealed caries in 3.6% of the nonditched margins and caries in 20% of the ditched margins. Microscopic examination revealed caries in 47.06% of the nonditched margins and caries in 58.82% of the ditched margins. Statistical analysis supports the conclusion that the marginal defect itself is insufficient to determine the presence of secondary caries that surround the amalgam restoration on the occlusal surface.

This article presents a comparative clinical study of reinforced zinc oxide eugenol (EBA) cement and amalgam used as retrograde root filling materials. All patients were followed for a minimum of 3 years after surgery. Clinical and radiographic evaluation was performed. Successful healing with complete bone regeneration was noted in 57% in the reinforced zinc oxide eugenol group compared with 52% in the amalgam group. Uncertain healing with a certain degree of bone regeneration was seen in 24% in the reinforced zinc oxide eugenol group compared with 19% in the amalgam group. Unsuccessful healing with failure of bone regeneration was seen in 20% in the reinforced zinc oxide eugenol group compared with 29% in the amalgam group. Statistical analysis failed to show any significant difference in healing between the two retrograde filling materials. The results of this study indicate that retrograde root filling with reinforced zinc oxide eugenol cement has a similar prognosis as with amalgam over a 3-year period.

The apical seal of amalgam retrograde fillings was evaluated in 86 extracted teeth. The experimental groups included retrofillings of amalgam alone, amalgam with a cavity varnish interface, and amalgam with a root canal sealer interface. After a 3-month immersion of the teeth in Higgins ink and subsequent clearing process, statistical analysis of ink penetration measurements showed significantly less leakage (p < 0.001) around amalgam retrofillings when using a root canal sealer as an interface between the retrograde cavity preparation and the condensed amalgam.

Black's class I classic cavity preparations were completed in 440 extracted, intact human premolars and restored with two silver amalgams and five different base materials with and without cavity varnish, which resulted in 20 combinations. A standard fluorescent dye test was performed and the percentage of marginal leakage recorded after storage for 7 days, 3 months, and 1 year in 1% NaCl at 20 degrees C. The results were computed by use of a linear logistic statistical analysis with a critical level of statistical significance of p < 0.05. Sealing improved with time and there was consistently better sealing in the first months without varnish, but after 1 year this was not significant. The low-copper amalgam recorded better sealing than the high-copper amalgam. A calcium hydroxide base promoted sealing but base-free cavities performed second best. Sealing declined with 1 year if Dycal base was used. Zinc-containing bases exhibited poor sealing, even those containing tin. Base solubility can improve sealing in calcium-containing bases but not in zinc-containing bases.

This study investigated post-core adaptation as it relates to core materials and post-head configuration. A total of 360 samples that consisted of three prefabricated post systems and three core materials of amalgam and composite resin of 1 and 3 mm post-head-covering thicknesses were made. Composite resin with a post-head covering of 3 mm was most resistant to compression, whereas amalgam was most resistant to retentive forces. The addition of titanium to composite resin as a reinforcement filler did not improve resistance to either compressive or tensile forces.

A conservative approach to amalgam restorations is presented for using a chemomechanical method for softening and removing decay and using a dental adhesive resin for bonding amalgam to tooth structure, reducing the need for mechanical retention and preserving sound tooth structure.

The effects of varying luting agent space and internal surface roughness with different types of cores and cements were studied. One hundred eighty amalgam and 180 composite cores were cemented into standardized stainless steel retainers. Cores and retainers were divided into 12 groups according to core type, core diameter, and retainer roughness. Each group was further subdivided according to cement, A: zinc phosphate (ZOP); B: resin; and C: glass ionomer cement (GIC). Subgroups were divided into thermal-cycled and nonthermal-cycled groups. Thermal cycling was at 5 degrees to 55 degrees C, repeated 500 times. Cores were separated from their retainers with a compression rod in an Instron testing machine at a crosshead speed of 0.02 cm/minute. Results were as follows: Amalgam cores were most retentive. Resin and ZOP cements were equally retentive with amalgam cores, but GIC was less retentive. Resin cores cemented with resin cement were more than twice as retentive than those cemented with ZOP or GIC cements. Retainers with rough internal surfaces were most retentive. A reduced cement space between core and retainer was most retentive. Thermal cycling reduced retention.

This clinical report describes a technique for restoring a maxillary right posterior segment using a combination of a conventional full-coverage retainer and adhesive resin-bonded retainer with a nonrigid connection, periodontal ridge augmentation, and a coronal-radicular amalgam alloy core. A technique has been outlined that allows for the preservation of the maximum amount of natural tooth structure while restoring a maxillary right posterior segment.

A recent survey of dental schools concluded that current efforts toward remediation are inadequate. A remedial waxing course providing recognition training before production attempts, emphasis on formative self- and peer-evaluation of projects, and application of a highly structured format for ensuring relevant practice had been developed and favorably evaluated previously. The current report follows the progress of two differently trained remedial groups and the remainder of the class in two courses following remediation. On the five subsequent practical examinations analyzed, the experimental group continued to perform at the class mean. On one practical examination, the experimental group significantly outperformed the traditional group (p less than 0.02). For three of the five examinations, the traditional group was significantly outperformed by the class. One of the six students in the experimental group required additional remediation. Of the seven in the traditionally remediated group, one left school and four required additional remediation. An apparent changing remediation pattern in the preclinical training period is described and possible reasons for the change are explored.

This article discusses a conservative class II amalgam cavity preparation that is similar to a cast onlay preparation except for the absence of the lingual and facial bevels. When extensive decay is removed and undermined cusps are present, onlays from amalgam support tooth structure and prevent fractures. To achieve this, cusps must be reduced to provide for a sufficient bulk of amalgam. The described technique can be applied to class II cavity preparations with weak cusps, class I cavity preparations when the remaining cavity provides adequate retention, and to endodontically treated teeth for which finances do not permit cast restorations.

This study investigated the influence of pins on the fracture resistance of three core materials. Two or four stainless steel pins were incorporated in either amalgam, composite resin, or alloy-reinforced glass ionomer specimens. Half of the pins were surface-treated with mercury, Panavia EX resin, or hydrochloric acid before they were incorporated in the respective materials. The pins were oriented in a direction relative to the tensile stress/axis of the specimen: parallel/perpendicular (PL/PR), perpendicular/parallel (PR/PL), or perpendicular/perpendicular (PR/PR). ANOVA tested significant differences in diametral tensile strength among materials, in number of pins, in pin orientations, in surface treatments, and in other interactions. Incorporation of pins weakened amalgam the most, followed by composite resin. Pins did not weaken amalgam-reinforced glass ionomer. Pin orientation improved the fracture resistance of some specimens by two times that of the controls. Orientation of pins parallel to the tensile stress was most favorable. As the number of pins increased, the fracture resistance of amalgam significantly decreased. Acid treatment of the pin surface enhanced the bond with composite resin. Both treatments resulted in significant improvement in fracture resistance.

Healing capacity after apicectomy was investigated in a randomized clinical study of 105 teeth apically sealed with either amalgam or glass ionomer cement. The results were evaluated clinically and radiographically after 1 year. The success rate was high for both materials: 91% for amalgam and 89% for glass ionomer cement. Contamination with moisture and blood adversely affected the outcome for both materials and was significantly more frequent in unsuccessful cases.

Thirty-six patients underwent endodontic surgery involving 66 teeth, with each root canal being retrofilled with either gold leaf or amalgam. A follow-up of most patients was conducted for 6 to 24 months. There was no significant difference in bone healing between the gold leaf-filled and amalgam-filled root cavities (p greater than 0.05). Gold leaf appeared to be a good alternative retrograde filling material and had a number of benefits over amalgam.

The use of pins or slots to provide retention for amalgam restorations has been shown to be equally effective by some authors whereas the pin method has been shown to be more effective by others. This study was done to determine whether the different methods would be affected by the outline form of the preparation. One hundred forty melamine teeth were prepared in three outline forms determined by the cusp that was removed: (1) mesiopalatal, (2) mesiopalatal and distobuccal, and (3) mesiopalatal, distobuccal, and mesiobuccal cusps. Each outline form was restored with a uniform volume of hand-condensed amalgam with pin or slot retention and milled to an occlusal angle of 30 degrees. A load was placed on the milled occlusion with a stainless steel ball to the point of fracture with an MTS machine. No significant difference was found between the pin or slot design for the outline forms evaluated.

In this investigation the effect of increasing the thickness of amalgam retrofilling on its sealing ability was studied and compared with the sealing ability of the laterally condensed gutta-percha with a sealer. The apical two thirds of the canals of 118 upper central incisors, filled with laterally condensed gutta-percha, were sealed with amalgam. Amalgam retrofills were also used to seal the apices of the roots of six teeth that had no other filling in their canals. The effectiveness of both techniques was determined by their ability to inhibit the penetration of methylene blue dye for the periods of 24 hours, 1 week, and 1, 3, and 6 months. At 24 hours both materials showed comparable sealing ability. However, the sealing ability of laterally condensed gutta-percha was significantly better than that of amalgam from the 1-week period until the end of the study. The depth of marginal penetration around both materials increased with time. The amount of the dye penetration increased acutely around amalgam, whereas its increase around gutta-percha was more uniform. At the end of the study, specimens retrofilled with amalgam exhibited total dye penetration that exceeded the full thickness of amalgam (6 mm) and spread into the root canal space. On the other hand, the mean value for marginal penetration of the dye around the laterally condensed gutta-percha was 2.6 mm at the end of the study. The present investigation proved beyond doubt that the use of any thickness of retrograde amalgam to seal the apex, with no other filling within the canal, invites failure.

The radiopacity of glass ionomer dental materials is quite variable. The use of a poorly radiopaque material as a base under other restorative materials can mislead the dentist to a diagnosis of recurrent decay. This study investigates the radiopacity of these materials and proposes a minimal radiopacity under which a material should not be used as a base or liner. All base, liner, and core formulations of glass ionomer under investigation were more radiopaque than dentin. All restorative and luting formulations of glass ionomer under investigation were less radiopaque than dentin and therefore should be avoided as bases or liners.

Cast restorations are the usual technique chosen for the restoration of posterior pulpless teeth. Complex amalgam restorations are suggested as an alternative method of treatment, and several advantages are described. Techniques to provide sufficient retention and resistance form include the use of threaded pins, amalgapins, slots and grooves, amalgam in the pulp chamber, or canals, or both, and posts cemented within the canals. The practicing clinician is advised to become familiar with these retention techniques so that difficult retention situations may be treated effectively.

The effect of pulp chamber depth and extension into the root canal space on fracture resistance was examined on endodontically treated teeth with coronal-radicular amalgam restorations. Six groups of 10 mandibular molars were mounted in acrylic resin, and crowns were ground apically until the wall height of the pulp chamber was 2, 4, or 6 mm. Three millimeters of gutta-percha was removed from the three canals of one-half the teeth and amalgam was condensed into the canal space to a height 7.5 mm above the cementoenamel junction (CEJ). The remaining teeth had amalgam condensed from the floor of the chamber to 7.5 mm above the CEJ. The amalgam restorations were loaded with an Instron instrument (Instron Corp., Canton, Mass.) until failure. Amalgam extension into the root canal space contributed minimally to the fracture resistance of the amalgam coronal-radicular restoration with four or more millimeters of chamber wall. If less than 4 mm of chamber wall height remained, however, the fracture load was substantially increased. Amalgam extension into the root canal space should be confined to teeth with limited remaining pulp chambers.

Difficulties with restoring class II cavities with posterior composite resin are enumerated. The problem is especially acute when a gingival margin lies close to or apical to the cementoenamel junction. A technique is described whereby the proximal portion of class II cavities is restored with amalgam to the contact area and composite resin inserted in the remainder of the cavity. Microleakage was studied by dye penetration tests. At the composite resin/cementum interface microleakage was significantly greater than at the amalgam/cementum and amalgam/composite resin interfaces (p less than 0.001). No statistically significant difference was observed in microleakage between the amalgam/cementum and amalgam/composite resin interfaces.

In this study, the sealing behavior of apical (retrograde) amalgam fillings was evaluated with particular regard to the nature of the amalgam and the manipulative procedures used. With the use of an in vitro air pressure test, four high-copper alloys and one traditional composition low-copper alloy were selected for determination of their microleakage characteristics. Measurements were made on both normal and water-contaminated mixes, and the effect of mix plasticity was evaluated. In addition, both setting and postsetting dimensional changes of these alloys were determined. The results showed that amalgams differ in their ability to provide a complete seal and that low plasticity mixes result in greater microleakage. All zinc-containing alloys that were contaminated with water exhibited a postsetting or delayed expansion. However, only the low-copper alloy exhibited a delayed expansion of a magnitude that might induce root fracture.

Cavity preparation causes cuspal flexure under simulated occlusal loads. During amalgam condensation, the dentist exerts forces on the tooth. After condensation, dental amalgam undergoes dimensional changes. We measured possible changes in the cuspal position of premolars during and after their restoration with dental amalgam. Strain gauges were attached to the buccal surfaces of the teeth, and a direct reading of the strain and a simultaneous time-strain curve were obtained. Measurements were taken at the onset of amalgam condensation and continued for 24 hours. The amalgam was then removed from the teeth, and a subsequent reading was made. On the basis of this model, we found that the use of amalgam as a restorative material caused a static load on the cusps of the teeth brought about their consequent permanent deformation. After amalgam removal, we observed complete elastic recovery for all the treated teeth.

This is a review of the literature concerning wear related to the following materials used in dentistry: dental amalgam, composite resins, and glass-ionomer cements, as well as natural tooth substance. Discussions are included on both in vivo and in vitro studies in which various methods were used to help determine wear resistance.