Assessment of iatrogenic damage to adjacent teeth during crown and bridge preparation.

INTRODUCTION: Iatrogenic damage to the adjacent tooth during crown preparation is a frequent disastrous effect. The aim of the study was, therefore, to determine the frequency of different types, degree and location of iatrogenic damage to the adjacent tooth during crown and bridge preparations in a tertiary care setting that lead towards the morbidity of tooth. MATERIALS AND METHODS: A prospective study was conducted in Aga Khan University dental laboratory in two months period in which a total of 150 dental casts fulfilling the inclusion criteria were analyzed using non-probability convenient sampling technique. The casts were examined using 3.5x magnifying loupes for the location, degree and type of damage to the proximal surface adjacent to the prepared tooth using Moonpar and Faulkner criteria. Data were analyzed by using SPSS version 22. Chi square test was used to assess the association between the experience of practitioner and degree of damage to adjacent tooth. It was also used to determine the association between location of tooth and degree of damage to adjacent tooth. Inter-examiner reliability was assessed by using kappa statistics. RESULTS: A high prevalence of damage to the proximal surface of adjacent teeth (78% on mesial tooth and 60.6% on distal tooth) was observed, with the majority (32.6%) belonging to the mild categories. There were statistically significant associations between the experience of practitioner and the damage to the surface mesial to the preparation. However, more severe damages occurred in mandibular teeth preparations as compared to maxillary teeth preparations. CONCLUSIONS: A high frequency of iatrogenic damage to the adjacent teeth had been found during crown and bridge work with the middle of the tooth as the most susceptible site. However, the majority of damages were of milder type including only abrasions.

Marginal Adaptation and Fracture Resistance of Lithium Disilicate Laminate Veneers on Teeth with Different Preparation Depths.

The purpose of this study was to evaluate the marginal adaptation and fracture load of ceramic laminate veneers on teeth with different preparation depths. A total of 75 extracted intact human maxillary central incisors were prepared with three different preparation depths (P) and assigned to the following five groups (n = 15): P1 (0.3-mm depth of preparation; preparation entirely in enamel); P2 (0.5-mm depth of preparation; preparation in enamel and dentin complex); P3 (1-mm depth of preparation; preparation entirely in dentin); P4 (no preparation, only surface roughening); and P5 (unrestored, intact teeth as control). A total of 60 lithium disilicate laminate veneers were fabricated. The marginal adaptation of the veneers was evaluated by light microscope and scanning electron microscope after cementation with resin cement. Finally, the veneers were loaded until fracture at a 90-degree angle to the lingual surface of the tooth. Statistical analyses were performed using analysis of variance and Tukey multiple range test. There was a significant difference between the marginal gap value of the distocervical measurement points of P1 and P2 and the distal measurement points of P3 and P4 (P = .33 and P = .017, respectively). The highest fracture resistance values were observed in the P5 group (mean: 389.55 ± 22 N) and the P2 group (mean: 322.86 ± 79.38 N), and the lowest values were observed in the P3 group (mean: 219.21 ± 60.74 N). The marginal adaptation of the laminate veneer restorations was not related to the depth of preparation. Mean fracture resistance of laminate veneers with 0.5-mm preparation depth was greater than that of the 0.3-mm and 1-mm preparation depth laminate veneers and those with no preparation.

Effect of a Calcium Phosphate Desensitizer on Pre- and Postcementation Sensitivity of Teeth Prepared for Full-Coverage Restorations: A Randomized, Placebo-Controlled Clinical Study.

PURPOSE: The aim of this study was to investigate the effect of Teethmate Desensitizer (TD), an aqueous slurry of calcium phosphates, on the pre- and postcementation sensitivity of contralateral premolars prepared for full-coverage restorations. MATERIALS AND METHODS: In this clinical study, using a split-mouth design, 20 patients were allocated and two contralateral vital premolars per patient were randomly assigned to treatment with TD and placebo (PLA; distilled water). One day after preparation and temporization, sensitivity (PRE) upon air blast (AB) and probe scratch (PS) was determined using a 10-cm-long visual analog scale (VAS). The trial was double-blinded; neither the patient nor the investigator knew the treatment performed. Sensitivity was assessed immediately after treatment, before seating the final crowns after 1 week, and 1 month after cementation. Statistical data analysis was performed with one-way analysis of variance followed by Tukey post hoc test and two-sided paired t test. Statistical significance was determined at α < .05. RESULTS: VAS scores upon stimulation with AB and PS were significantly lower at POST and 1 week, and with AB after 1 month. TD-treated teeth showed significantly less sensitivity than PLA. At the postcementation recall, TD and PLA were not significantly different and the average pain scores were almost 0. CONCLUSION: Treatment of teeth prepared for full crown restorations with TD can significantly reduce pre- and postcementation sensitivity.

A prospective study of the incidence of asymptomatic pulp necrosis following crown preparation.

AIM: To determine the incidence of asymptomatic pulp necrosis following crown preparation as well as the positive predictive value of the electric pulp testing. METHODOLOGY: A total of 120 teeth with healthy pulps scheduled to receive fixed crowns (experimental teeth) were included. Teeth were divided into two groups according to the preoperative crown condition (intact teeth and teeth with preoperative caries, restorations or crowns) and into four groups according to tooth type (maxillary anterior teeth, maxillary posterior teeth, mandibular anterior teeth and mandibular posterior teeth). Experimental and control teeth were submitted to electric pulp testing on three different occasions before treatment commencement (stage 0), at the impression making session (stage 1) and just before the final cementation of the crown (stage 2). Teeth that were considered to contain necrotic pulps were submitted to root canal treatment. Upon access, absence of bleeding was considered as a confirmation of pulp necrosis. Data were analysed using bivariate (chi-square) and multivariate analysis (logistic regression). All reported probability values (P-values) were based on two-sided tests and compared to a significance level of 5%. RESULTS: The overall incidence of pulp necrosis was 9%. Intact teeth had a significantly lower incidence of pulp necrosis (5%) compared with preoperatively structurally compromised teeth (13%) [(OR: 9.113, P = 0.035)]. No significant differences were found amongst the four groups with regard to tooth type (P = 0.923). The positive predictive value of the electric pulp testing was 1.00. CONCLUSIONS: The incidence of asymptomatic pulp necrosis of teeth following crown preparation is noteworthy. The presence of preoperative caries, restorations or crowns of experimental teeth correlated with a significantly higher incidence of pulp necrosis. Electric pulp testing remains a useful diagnostic instrument for determining the pulp condition.

Early complications and short-term failures of zirconia single crowns and partial fixed dental prostheses.

STATEMENT OF PROBLEM: Ceramic single crowns fabricated from newer materials, especially zirconia, have shown relatively high survival rates. However, early reversible complications may increase the risk of an irreversible failure later. PURPOSE: The purpose of the study was to evaluate the early complications and short-term failures of zirconia single crowns and partial fixed dental prostheses (FDPs) made by predoctoral dental students. MATERIAL AND METHODS: Data were collected from the patient records. Altogether, 264 zirconia single crowns and 120 FDPs (342 abutments and 190 pontics) were fabricated for 173 patients between 2007 and 2010. Early complications were recorded during the prosthetic treatment phase, and short-term failures were recorded during the first year in use. RESULTS: The most frequent early complications were localized gingival irritation (1.9% of single crowns and 2.5% of FDP) and postoperative tooth sensitivity (0.4% of single crowns and 3.3% of FDPs). Pulp exposure during preparation was recorded in 3 abutment teeth of the FDPs. The most frequent short-term failure was chipping of the veneering porcelain (0.8% for single crowns, 0.8% for FDPs). One crown lost cementation because of poor retention (0.4%), and 2 FDPs failed because of framework fractures (1.7%). CONCLUSIONS: The most frequent early complications were localized gingival irritation and postoperative tooth sensitivity, and the most frequent short-term failure was chipping of the veneering porcelain.

Lemierre's syndrome: a serious complication of a routine dental procedure.

Lemierre's syndrome is the clinical presentation characterized by oropharyngeal or tonsillar infection, anaerobic septicaemia often with distant septic emboli, and clinical or radiological evidence of thrombosis of the internal jugular vein. We report a case of Lemierre's syndrome in a 44-year-old type II diabetic male. This case is unique for two reasons. Firstly, we believe it is the first reported iatrogenic case following a routine dental procedure. Secondly, the internal jugular vein thrombosis was found to occur on the contralateral side to the primary infection.

Subcutaneous emphysema to the head and neck resulting from a dental crown preparation.

CASE REPORT: A 59-year-old African-American female presents with subcutaneous emphysema to the head and neck region resulting from routine dental treatment with a high speed air-driven handpiece. The patient had a chief complaint of generalized edema, dysphagia and pain to her face and neck. The patient subsequently was admitted to the intensive care unit for airway monitoring. PURPOSE: To alert the dental community about the incidence of iatrogenic subcutaneous emphysema from a routine dental procedure, and how to recognize and manage its occurrence.

A comparison of the efficacy of potassium nitrate and Gluma desensitizer in the reduction of hypersensitivity in teeth with full-crown preparations.

AIM: The aim of this clinical investigation was to compare the efficacy of Gluma Desensitizer and potassium nitrate desensitizing agents on the reduction of hypersensitivity of teeth prepared for full coverage crowns. METHODS AND MATERIALS: This study included 75 vital teeth in 25 patients in need of fixed prosthesis treatment. After completing routine examinations, hypersensitivity of the teeth was measured using an air sensitivity test. The measurement of sensitivity was using a Visual Analog Scale (VAS) before preparation, after preparation, before using desensitizers, after using desensitizers, and before cementation. Each tooth was randomly put into one of the three groups of 25 teeth according to the desensitizing agent used (potassium nitrate, Gluma, and the control). In each patient potassium nitrate was used on one of the abutments and Gluma was used on the other abutment and on the third abutment (the control) no substance was used. RESULTS: Both desensitizers decreased dentinal hypersensitivity in vital teeth prepared for full-coverage crowns, but potassium nitrate was more effective when applied before cementation. In 88% of the teeth to which Gluma was applied a vascular pain (with pulse) was present. CONCLUSION: The results of this investigation suggest the application of potassium nitrate to dentin in full crown preparations prior to cementation reduces post-operative sensitivity. CLINICAL SIGNIFICANCE: Clinical experiments show the preparation of vital teeth for full coverage crowns can cause sharp, transient pain as a result of dentinal hypersensitivity in the majority of cases. Several different substances and methods have been suggested for reducing such hypersensitivity including costly laser treatments. However, the findings of this study indicate the use of desensitizer substances such as potassium nitrate can reduce tooth hypersensitivity efficiently with less expense.

Effect of remaining coronal structure on the resistance to fracture of crowned endodontically treated maxillary first premolars.

OBJECTIVE: Endodontically treated maxillary first premolars present a restorative challenge. The objective of the present study was to assess the resistance to fracture of crowned endodontically treated maxillary first premolars under simulated occlusal load, while preserving various degrees of remaining coronal structure. METHODS AND MATERIALS: The study consisted of 50 intact maxillary first premolars with bifurcated roots and similar root diameter and length, randomly divided into 5 equal experimental groups. All dowels were luted with Flexi-Flow titanium-reinforced composite resin cement. TiCore titanium-reinforced composite resin was used to fabricate the core. Complete cast crowns were fabricated and cemented with zinc phosphate cement. Forces at fracture and mode of failure were recorded. RESULTS: Statistically significant differences (P < .05) were found among mean failure forces for all tested groups in their resistance to fracture under load with the Kruskal-Wallias test and among all combinations of the 5 groups (Z = -1.56/-2.34; P > .05) with the Mann-Whitney test. This indicates that crowned maxillary first premolars with varying degrees of remaining coronal structure differ significantly in their resistance to fracture under occlusal load. There was increased protection against fracture under occlusal loads with more remaining tooth structure. CONCLUSIONS: Within the limitations of this study, remaining coronal structure influenced the fracture resistance of crowned endodontically treated maxillary first premolars. Preservation of tooth structure is important for its protection against fracture under occlusal loads and may influence the tooth prognosis.

In vitro fracture resistance and deflection of pulpless teeth restored with fiber posts and prepared for veneers.

The aim of this in vitro study was to evaluate the influence of endodontic therapy, veneer preparation, and their association on fracture resistance and deflection of pulpless anterior teeth and assess whether restoration with quartz fiber-reinforced post can influence these properties. Seventy-five freshly extracted human maxillary central incisors were selected. Teeth were randomly divided into 4 experimental groups (veneer preparation/endodontic therapy/endodontic therapy and veneer preparation/endodontic therapy, veneer preparation, and fiber post placement) and a control group (n = 15). Specimens were loaded to fracture recording crown deflection under load, and data were statistically analyzed. Veneer preparations and endodontic treatment did not significantly influence fracture resistance of maxillary incisors. On the contrary, preparation for veneer significantly increased the deflection values of the specimens. Fiber post restorations seemed to significantly increase mean maximum load values for specimens prepared for veneers. A fiber-reinforced post restoration can be suggested when endodontic treatment is associated with veneer preparation.

Cervicofacial and mediastinal emphysema after crown preparation: a rare complication.

Cervicofacial emphysema is a well-known complication associated with the use of a high-speed air turbine. However, retropharyngeal emphysema or pneumomediastinum in the absence of severe trauma is rare. Immediate recognition of this phenomenon is essential to avoid life-threatening complications such as potential airway obstruction or venous air embolism. This article reports a case of gas diffusion into the mediastinum after dental preparatory treatment for a single-tooth crown. Pneumomediastinum should be considered whenever there are anamnestic data for retrosternal chest pain accompanied by dysphagia, dysphonia, or dyspnea caused by cervicofacial emphysema after dental treatment.

Surgical emphysema following a restorative procedure: A case report.

UNLABELLED: Surgical emphysema is a rare complication following a restorative procedure, despite the use of air-driven handpieces. Although most cases resolve spontaneously, it should be correctly managed to avoid potentially life-threatening situations, such as pneumomediastinum and pneumothorax. CLINICAL RELEVANCE: Surgical emphysema, although rare, can occur following certain dental procedures. It should be avoidable but, when it occurs, appropriate management is essential.

Dentin exposure in tooth preparations for porcelain veneers: a pilot study.

STATEMENT OF PROBLEM: The various clinical techniques available for even reduction of a tooth surface to receive a porcelain veneer restoration do not produce a consistently even conservative reduction. In addition, it is not known which technique is most conservative of enamel. PURPOSE: The purpose of this pilot study was to assess the effectiveness of 3 clinical techniques, namely, dimple, depth groove, and freehand, in producing an intraenamel preparation. The relation between overpreparation beyond the commonly accepted depth of preparation of 0.5 mm and dentin exposure was also examined. MATERIAL AND METHODS: A single operator prepared 3 groups of 5 extracted maxillary central incisors to a depth of 0.5 mm using dimple, depth-groove, and freehand methods of tooth preparation. The prepared teeth were scanned using an x-ray microtomography scanner. The reconstructed images were studied using software that provided a volume-rendering routine so that, by choosing suitable x-ray linear attenuation coefficient thresholds, enamel (2.78 cm(-1) at 40 keV) and dentin (1.63 cm(-1) at 40 keV) surfaces could be viewed. The percentage area of enamel conserved was analyzed from these images. Coordinate metrology was used to produce color-coded images depicting the depth of preparation. The Kruskal-Wallis test was used to determine the statistical significance (alpha=.05) in the difference between the mean percentage area of enamel conserved in the 3 technique groups. The coordinate metrology and x-ray microtomography images were visually compared to study the correlation between overpreparation and dentin exposure. RESULTS: The Kruskal-Wallis test did not demonstrate significant difference (P=.07) between the 3 techniques in conserving enamel. However, the dimple technique showed a greater trend to retaining a larger mean percentage area of enamel (77.5% +/- 14.2) compared to depth-groove (50.1% +/- 17.5) and freehand (76.8% +/- 24.4) techniques. Preparation depth in the range of 0.4 to 0.6 mm was largely seen to be intraenamel, except in the cervical region. CONCLUSION: Within the limitations of this pilot study, the 3 different techniques tested did not differ significantly in conserving enamel.

Subcutaneous cervicofacial emphysema and pneumo-mediastinum: a rare complication after a crown preparation.

Subcutaneous cervicofacial emphysema and pneumo-mediastinum are relatively rare complications from different dental procedures (including oral surgery and restorative treatment). Many cases go unrecognized or are misdiagnosed. While the majority of cases resolve spontaneously, some can lead to life-threatening complications that require emergency intervention. This article presents a case report of subcutaneous and mediastinal emphysema following a routine restorative dental procedure. The differential diagnosis and management of this condition is discussed.

An in vitro study of dentin exposure during resin-bonded fixed partial denture preparation.

OBJECTIVES: The aim of this in vitro study was to investigate whether dentin is exposed during tooth preparation for resin-bonded fixed partial dentures and, if so, to quantify the amount of dentin exposure. METHOD AND MATERIALS: Twenty extracted premolars were prepared in the following manner: The palatolingual and proximal axial surfaces were reduced by 0.50 mm. Mesial and distal grooves, 1.00 mm in depth, and mesial and distal occlusal rest seats, measuring 2.00 mm buccolingually x 1.50 mm mesiodistally x 1.00 mm deep, were prepared. The specimens were stained with a modified van Gieson's stain to identify dentin exposure, mounted on a jig to allow standardization, and photographed after 30-degree rotation to create a panoramic image of each tooth. The image was modified and analyzed to measure the percentage of the preparation area that exhibited dentin exposure. RESULTS: Dentin exposure was noted in all specimens. The mean area of dentin exposure was 11.06 mm2 (16.15% of the preparation area). The minimum and maximum areas of dentin exposure were 4.07 mm2 (7.03%) and 19.73 mm2 (27.28%), respectively. CONCLUSION: Dentin is exposed during resin-bonded fixed partial denture preparation if current tooth preparation guidelines are followed, despite the commonly made recommendation that the preparation remain within enamel. The region of the grooves consistently exhibited exposed dentin; exposure at the cervical margin was variable.

Comparison of using calcium hydroxide or a dentine primer for reducing dentinal pain following crown preparation: a randomized clinical trial with an observation time up to 30 months.

The purpose of this study was to evaluate effect of a calcium hydroxide suspension [Ca(OH)2] or glutaraldehyde based dentine primer (GDP) to reduce tooth sensitivity after full crown preparation. Thirty-six patients were treated with Ca(OH)(2) on one tooth and with GDP on another. Patients completed a questionnaire regarding sensitivity during crown preparation, when the not-anaesthetized abutments were irritated [cotton pellet (20 degrees C)]. The teeth were tested before (T(0)) and after using the desensitizer (T(1)), again after 7 days (T(2)), 6 months (T(3)) and 30 months (T(4)). The results were registered on a visual analogue scale [0 (no pain)-100 (severe pain)]. The changes of tooth sensitivity between different testing times were analysed. The median and the (interquartile range) for the different time intervals for Ca(OH)(2) were DeltaT(0)-T(1): 5 (6-17), DeltaT(0)-T(2): 17 (14-32), and for GDP, DeltaT(0)-T(1): 9 (7-18) DeltaT(0)-T(2): 18 (16-33), the decreases in sensitivity were lower for DeltaT(0)-T(1) than for DeltaT(0)-T(2) for both desensitizers (P < 0.001). There was no statistical difference (P > 0.05) between the agents (DeltaT(0)-T(1), DeltaT(0)-T(2), DeltaT(3)-T(4)). Both substances might be useful in reducing tooth sensitivity after crown preparation, but no differences in the efficacy were found when comparing the materials.

Influence of timing of coronal preparation on retention of cemented cast posts and cores.

PURPOSE: This study investigated the effect of coronal preparation by high-speed handpiece on the retention of cemented cast posts and cores. MATERIALS AND METHODS: Cast posts and cores were fabricated for 90 extracted single-rooted human teeth cemented with zinc-phosphate cement and randomly divided into six groups of 15 specimens each. The six groups were matched randomly two by two, such that one of each of the matched groups was subjected to a 4-minute period of high-speed preparation of the cores. Castings from the first pair (1 and 2) were subjected to an axially directed removal force using a universal testing machine 15 minutes from the start of cement mixing; castings from the second (3 and 4) and third (5 and 6) pairs were tested at 1 hour and 24 hours, respectively, having been stored in water at 37 degrees C for the waiting periods. The forces required for dislodgment of posts from their prepared spaces were recorded. Data were statistically analyzed using two- and one-way ANOVA and the Student's t test. RESULTS: The results showed increased mean retentive strengths of posts as the time to testing increased for both unprepared and prepared groups. Significantly higher mean retentive strengths of posts were recorded for unprepared compared to prepared groups tested at 15 minutes and 1 hour after cementation. CONCLUSION: High-speed preparation had a significant negative effect on the retentive strengths of posts tested at 15 minutes and 1 hour after cementation, but not on those tested at 24 hours.

Dentin permeability and eugenol diffusion after full crown preparation.

PURPOSE: To compare teeth prepared to receive a metallic versus a metal-ceramic crown with respect to (1) in vitro dentin permeability before and after using a desensitizing agent and (2) pulpal eugenol concentration after sealing a temporary crown with a zinc oxide-eugenol based cement. MATERIALS AND METHODS: The roots of 20 human mandibular molars were separated and the crowns were prepared to receive a metallic crown. The hydraulic conductance was recorded before and after using Protect dentin desensitizer. The crowns were then further reduced to receive a metal-ceramic crown and the hydraulic conductance was recorded under the same conditions, on deeper dentin, before and after using the desensitizing agent. Twenty additional teeth were prepared: 10 to receive a metallic crown and 10 teeth to receive a metal-ceramic crown. A tube filled with 1 mL phosphate buffered saline (PBS) was sealed to the cementoenamel junction. A temporary crown was sealed onto the preparation with Temp Bond. The amount of eugenol that diffused across dentin into PBS was spectrofluorimetrically measured at Day 1 and Day 7. The crown preparations were vertically sectioned and the dentin remaining thickness was recorded. RESULTS: The hydraulic conductance of teeth prepared for a metal-ceramic crown was twice as high as teeth prepared for a metallic crown (P < 0.001). The desensitizing agent reduced the hydraulic conductance in both groups (P< 0.001). The two groups showed the same hydraulic conductance after using Protect (ns). No significant difference was found in the amount of eugenol diffusion between the two groups of teeth although eugenol diffusion decreased with time (P < 0.01). No correlation was found between eugenol diffusion and remaining dentin thickness.