The relationship of the position of crown margins to gingival health

Clinical evaluation of posterior zirconia-based and porcelain-fused-to-metal crowns with a vertical preparation technique: an up to 5-year retrospective cohort study

OBJECTIVE

To evaluate the clinical conditions of single-unit posterior restorations on teeth prepared without finishing line, after 5.6 years of clinical service.

MATERIALS AND METHODS

50 crowns (25 zirconia-based (Zr) and 25 porcelain-fused-to-metal (PFM)) were selected from 34 patients. The restorations were evaluated according to the California Dental Association (CDA) Quality Criteria, and periodontal variables were studied in the abutment teeth compared with the unrestored contralateral teeth. Variables were examined using Mann-Whitney and Pearson´s Chi-Square tests (α = 0.05). The success of the prosthesis was calculated using Kaplan-Meier test.

RESULTS

CDA Quality Criteria was considered satisfactory-excellent in all restorations except for one of them, due to chipping on a PFM crown. At, 66 months, the success rates for PFM and Zr crowns were 85.7 % and 100 %, respectively. The plaque index (PI) showed that the restored abutment teeth accumulated significantly less plaque than the control teeth, but the gingival index (GI) was statistically higher in the abutment teeth. In 80 % of cases the probing depth (PB) was ≤3 mm. In addition, in 21 % of the cases, gingival recession was less than 2 mm. The restoration material had a statistically significant effect on GI and PB, with Zr crowns showing less inflammation and less deep pockets than PFM restorations. On the contrary, greater gingival recession was found at the margins of the Zr crowns when compared to the PFM. No statistical differences were found between the two materials in the GI.

CONCLUSIONS

Cemented crowns on vertical preparations show good clinical behavior after 5 years. The periodontal parameters (PI, GI, PD) of the Zr restorations are significantly better than those of PFM, with the exception of gingival recession.

CLINICAL RELEVANCE

The use of restorations on vertically prepared teeth is a suitable alternative to classical horizontal preparations.

Biocompatibility and acid resistance of preformed crowns in children: an in vitro study

PURPOSE

To investigate the in vitro biocompatibility of human gingival fibroblasts with preformed paediatric crowns and resistance to acid exposure at levels that simulate the oral environment.

METHODS

This laboratory study investigated primary HGFs viability, metabolic activity, cytotoxicity, and apoptotic events on preformed metal crown discs, composite resin-coated wells, and monolithic zirconia fragments at 24, 48, and 72 h using the ApoTox-Glo Triplex assay. The PPCs were also immersed in 0.1% lactic acid, 0.2% phosphoric acid, or 10% citric acid for 7 days at 37 °C to reproduce conditions associated with dietary intake or gastric reflux. Samples were then subject to inductively coupled plasma optical emission spectrometry to quantitate the release of ions.

RESULTS

The viability of HGFs on stainless steel and CR significantly declined at 48 and 72 h, representing potential cytotoxicity (p < 0.05). Cytotoxicity of HGFs was also higher for stainless steel and ZR compared to control (p < 0.05). PMCs and ZR crowns gave minimal ion release. Meanwhile, significant quantities of metallic ions, including copper (Cu), iron (Fe), nickel (Ni), and zinc (Zn), were present in eluates from veneered-preformed metal crowns.

CONCLUSION

As PPCs can be exposed to highly acidic environments for many years, thus the release of metallic ions from V-PMCs should form the further investigation in future studies.

Forced surgical extrusion using an axial tooth extraction system as a practicable technique for preserving severely destroyed teeth? - Clinical outcomes up to 4.8 years

OBJECTIVE

Several extrusion techniques have been described to restore teeth with insufficient coronal tooth structure and to avoid their extraction. Still, there is little evidence for a treatment concept combining surgical extrusion using an atraumatic axial extraction system.

MATERIALS AND METHODS

A total of nine patients, each with an iso- or subgingival fractured tooth, were retrospectively examined. Treatment of the damaged tooth comprised an atraumatic forced surgical extrusion performed with an axial tooth extraction system and a more coronal positioning within the socket. The teeth were initially splinted and subsequently restored. The follow-up period was up to 57.1 months and averaged 36.5 (SD: ±13.5) months.

RESULTS

All nine teeth were still in situ, without signs of inflammation. During the period of the provisional restoration, six prosthetic complications occurred, which were resolved with little effort, whereas, success rate for the definitive restoration was 100%. No biological complications were observed concerning the root apex or soft tissue. The radiographically measured mean extrusion distance was 3.4 (SD: ±1.0) mm, so that a sufficient prosthetic ferrule could be reestablished.

CONCLUSIONS

Surgical extrusions using an axial tooth extraction system demonstrate low biological and prosthetic complications rates over observation time.

CLINICAL SIGNIFICANCE

The presented extrusion approach preserves soft and hard tissue and is an efficient treatment option for severely destroyed teeth. Saving hopeless teeth by this relatively predictable and feasible procedure has hardly any disadvantages for patients, and in case of failure, an implant or fixed partial denture are still an option.

The effect of biologically oriented and subgingival horizontal preparation techniques on periodontal health: A double-blind randomized controlled clinical trial

Purpose

The aim of this study was to investigate and compare the influence of subgingival horizontal preparation technique (SHPT) and biological oriented preparation technique (BOPT) on periodontal health at a split-mouth model.

Methods

The sample of 100 patients was divided into two groups using a spilt-mouth study design; each patient had received two crowns with SHPT and BOPT respectively. The teeth were randomly allocated for the preparation techniques. All prepared teeth were restored with fabricated zirconium cores and ceramic layering. Temporary crowns were delivered after taking an impression and patients were recalled for the final cementation of the crowns. After that, follow-up recalls were set at one month, 3 months, 6 months, one year, and two years to record the following clinical parameters; plaque index, probing depth, bleeding on probing, clinical attachment level and patients' satisfaction with treatment.

Results

SHPT had significantly lower plaque and inflammation index at baseline, which increased significantly at 3 months and 2 years' follow-up compared to BOPT. Patients' satisfaction was significantly higher with SHPT at baseline, and it is reduced significantly at 6 months and two years follow- up (P < 0.001). The probing depth was significantly higher in BOPT at baseline and 3 months and decreased significantly at 6 months, 1 year, and 2 years' follow-up.

Conclusion

BOPT is a favorable technique with a full crown or veneer, presenting good marginal stability and periodontal behavior.

Exploring the Biological Width in Dentistry: A Comprehensive Narrative Review

Biological width (BW) is the distance established from the junctional epithelium and connective tissue attachment to the root surface of a tooth. It acts as a natural seal protecting the tooth from infections and diseases. The normal dimension of it is 2.04 mm on average. A periodontal probe is used to determine BW in routine clinical practice. Various methods are available for the determination of BW. A diagnosis of BW violation is asserted when the distance is found to be less than 2 mm at single or multiple locations. Gingival health is of utmost importance when considering the long-term health of the tooth as well as any restoration. A plethora of BW violations can lead to a myriad of complications, which are discussed briefly in this article. The article also aims to highlight BW in relation to restorative margins and implants and its clinical assessment as well as shed light on the procedure that can be employed to correct BW violations in dental practice.

Evaluation of biologic width re-establishment using CHU aesthetic gauges in crown lengthening cases- a clinical study

Background

Present study was performed to assess the biologic width relocation by performing aesthetic crown lengthening with the help of Chu aesthetic gauges.

Methods

The study included 192 teeth from 17 individuals, of which 64 teeth underwent crown lengthening (Treated site- TS) and 128 of which shared a proximal surface (Adjacent site -AS, Non-Adjacent site- NAS) with the surgery site. The clinical parameters Plaque index (PI), gingival index (GI), gingival margin position (PGM), relative attachment level (RAL), bone sounding (BS), biological width (BW), and probing depth (PD) were recorded. The clinical recordings were made at three different times: at baseline, 3 and 6 months post-operatively. Statistical analysis was performed using one way ANOVA and for pair wise comparisons post hoc Tukey test was used. Data was expressed in mean and standard deviations. P < 0.05 was considered statistically significant.

Results

PI and GI showed significant difference (p = 0.000*) at all time intervals. PGM and RAL were significant from baseline to 3 months, baseline to 6 months (p = 0.000*) while non-significance (p > 0.05) was recorded at 3-6 months comparison for PGM, RAL, BS, BW and PD.

Conclusion

Present study concluded that usage of Chu Aesthetic gauges help in controlled removal of soft and hard tissues, biologic width and gingival margin position got stabilized within 3 months and final prosthesis can be advised after 3 months of surgery.

Trueness of intraoral scanners according to subgingival depth of abutment for fixed prosthesis

This study aimed to compare the trueness of intraoral scanners (IOSs) according to the subgingival finish line depth of tooth preparation for fixed prostheses. The prepared maxillary right first molar was fabricated by using ceramic material. A computer-aided design (CAD) reference model (CRM) of the abutment was obtained by using a contact scanner. The subgingival finish line was located according to the depth at 0-mm, 0.25-mm, 0.5-mm, 0.75-mm, and 1-mm. CAD test models (CTMs) were obtained by using 2 IOSs (i500 and CS3600). CRM and CTM were superimposed and analyzed (Geomagic control X). The one-way analysis of variance (ANOVA) was used to compare the trueness according to the subgingival finish line depth. The paired t test was used to compare the trueness of IOSs with and without gingival retraction (α = .05). When the gingival displacement code was not used, it was observed that the trueness of both IOSs decreased significantly as the depth of the subgingival finish line increased (P < 0.001). When the subgingival finish line was positioned deeper than 0.5-mm, the trueness of both IOSs exceeded 100 µm in the marginal region. When the gingival displacement cord was used, the trueness of both IOSs did not exceed 100 µm regardless of the subgingival finish line depth. When gingival cord was used, it showed significantly higher trueness than when not used (P < 0.001). When the gingival displacement cord was not used, the trueness of IOSs decreased as the subgingival finish line depth increased. But the use of the gingival displacement cord improved the scanning trueness by 90%. Thus, it is necessary to use the gingival displacement cord according to the clinical situation to improve scan trueness at the subgingival finish line.

Periodontal clinico-morphological changes in patients wearing old nickel-chromium and copper alloys bridges

Elderly population frequently presents more than one prosthetic restoration realized from different types of dental alloys which, in time, suffer various alterations in the oral environment. Metallic ions are released in saliva due to its electrolytic qualities, interacting with the contact tissues. Studies regarding cytotoxicity of dental alloys are providing contradictory results. Besides biocompatibility, the microbial factor is also greatly influencing the long-term success of the prosthetic rehabilitation. This study's aim was to assess the response of the gingival tissue to nickel-chromium (Ni-Cr) and copper (Cu)-based dental casting alloys from fixed dentures present in many patients from Romania. Gingival samples were taken from 124 patients wearing fixed dental restorations made from these two types of alloys from injured areas surrounding the abutment teeth; histological specimens were prepared, fixed in 10% neutral buffered formalin, paraffin-embedded and stained with Hematoxylin-Eosin (HE). Histological analysis showed the existence of a chronic inflammatory infiltrate in the gingival chorion, necrosis areas, and vascular congestion. Various morphological alterations appeared, depending on the intensity of the inflammation and the immune response. The surface epithelium suffered a hyperplasic reaction, either limited to acanthosis or involving the whole epithelium, the release of the Cu(2+) and Ni(2+) ions from the dental alloys used in bridges and crowns being responsible for inducing gingival hyperplasia and a chronic inflammation in the areas situated around the abutment teeth. The immunohistochemical study allowed us to observe an increased number of positive cluster of differentiation 3 (CD3) T-lymphocytes in periodontium, proving that the cellular immune response is rapid and intense.

Minimal invasive microscopic tooth preparation in esthetic restoration: a specialist consensus

By removing a part of the structure, the tooth preparation provides restorative space, bonding surface, and finish line for various restorations on abutment. Preparation technique plays critical role in achieving the optimal result of tooth preparation. With successful application of microscope in endodontics for >30 years, there is a full expectation of microscopic dentistry. However, as relatively little progress has been made in the application of microscopic dentistry in prosthodontics, the following assumptions have been proposed: Is it suitable to choose the tooth preparation technique under the naked eye in the microscopic vision? Is there a more accurate preparation technology intended for the microscope? To obtain long-term stable therapeutic effects, is it much easier to achieve maximum tooth preservation and retinal protection and maintain periodontal tissue and oral function health under microscopic vision? Whether the microscopic prosthodontics is a gimmick or a breakthrough in obtaining an ideal tooth preparation should be resolved in microscopic tooth preparation. This article attempts to illustrate the concept, core elements, and indications of microscopic minimally invasive tooth preparation, physiological basis of dental pulp, periodontium and functions involved in tool preparation, position ergonomics and visual basis for dentists, comparison of tooth preparation by naked eyes and a microscope, and comparison of different designs of microscopic minimally invasive tooth preparation techniques. Furthermore, a clinical protocol for microscopic minimally invasive tooth preparation based on target restorative space guide plate has been put forward and new insights on the quantity and shape of microscopic minimally invasive tooth preparation has been provided.

Ceramic veneers on central incisors without finish line using bopt in a case with gingival asymmetry

Objectives

This clinical case report describes the rehabilitation of central incisors with veneers in a patient with gingival asymmetry. The teeth were prepared without finish line, applying BOPT concepts to correct asymmetry, and obtained a harmoniously integrated restoration with optimal periodontal health.

Clinical implications

Biologically oriented preparation technique (vertical or “feather edge” preparation) was used to obtain gingival symmetry. Teeth were prepared without horizontal finish line to achieve correct emergence, soft tissue adaptation and stabilization, while maintaining biological space, both at the provisional restoration stage and later when definitive restorations were placed. To perform the technique correctly, it is essential to perform adequate periodontal diagnosis to verify the space available between the bone crest and the future margin of the restoration.

Conclusions

It is possible to correct gingival asymmetry by performing dental preparation without finish line providing a correct periodontal analysis is first performed, which will contribute to successful soft tissue stabilization.

Clinical Significance

Beyond of all the prosthodontic preparation techniques, knowledge of B.O.P.T. (Biological Oriented Preparation Technique) allows us to achieve predictable and consistent results in terms of periodontal health and gingiva architecture surrounding ceramic veneers. Nevertheless long term studies are necessary to ensure the benefits of this techniques.

Key words:Gingival margin, emergence profile, biologically oriented preparation technique.

[Minimal invasive microscopic tooth preparation based on endodontic, periodontal and functional health]

Tooth preparation is the primary and core operation technique for dental esthetic restoration treatment, due to its effect of providing restoration space, bonding interfaces and marginal lines for dental rehabilitation after tooth tissue reduction. The concept of microscopic minimal invasive dentistry put forward the issue of conducting high-quality tooth preparation, conserve tooth-structure, protect vital pulp and periodontal tissue simultaneously. This study reviewed the concepts, physiology background, design and minimal invasive microscopic tooth preparation, and in the meantime, individualized strategies and the two core elements of tooth preparation (quantity and shape) are listed.

Update on Perio-Prosthodontics

Knowledge of the periodontal-restorative interface is critical in the fabrication of restorations that are functional and esthetic. Understanding biological principles allows the clinician to predict how the periodontium will respond to restorative therapy. Factors that influence the response to therapy in the periodontal-restorative interface are periodontal biotype, gingival architecture, alveolar crest position, gingival margin position, and gingival zenith.

Gingival Health of Porcelain Laminate Veneered Teeth: A Retrospective Assessment

STATEMENT OF PROBLEM

The long-term effect of the presence of porcelain laminate veneers (PLVs) on the health of the surrounding gingival issues is not available in the restorative literature.

PURPOSE

To assess the long-term effect of PLVs on the health of the surrounding gingival tissues. A secondary aim was to correlate gingival crevicular fluid (GCF) scores with clinical parameters used for gingival health assessment in teeth treated with PLVs.

METHODS AND MATERIALS

Patients who received PLVs placed at the Graduate Restorative Clinic within a seven- to 14-year period were recalled for clinical evaluations. Periodontal measurements including gingival index (GI), periodontal pocket depth (PPD), gingival recession (GR), and clinical attachment level (CAL) were measured using a standard probe and indices. Gingival Crevicular Fluid (GCF) was measured with a Periotron machine (Periotron 8000, Oraflow Inc), using Periopaper (Periopaper Gingival Fluid Collection Strip, Oraflow Inc.) for fluid collection. Photographs of any observed clinical defect were taken. Data were tabulated using Excel 2010 (Microsoft Corp). Statistical analysis for all descriptive statistics was performed using SPSS 21 (SPSS Software, IBM Corp.) and Stata SE 13 (Stata Software, StataCorp). Repeated-measures analysis of variance (ANOVA) was done to test for statistical significance of the mean pocket depths between the restored and unrestored surfaces of the veneered teeth. The significance level for all tests was p<0.05. Pearson's correlation coefficient was performed for testing statistical significance between GCF and GI and between GCF and PPD.

RESULTS

The frequency distribution of the GI included 47 PLVs (43%) with normal gingiva, 16 (15%) with mild inflammation, and 46 (42%) with moderate inflammation and bleeding on probing. The average PPD on the facial surface of the maxillary and mandibular PLVs was 2.17 mm and 2.16 mm, respectively. On the lingual surface, the average PPD was 2.10 mm for maxillary and 2.22 mm for mandibular PLVs. Gingival recession was seen in 27% of the evaluated PLVs. The repeated-measures ANOVA revealed p≥0.136, showing no statistical difference in the mean pocket depths between restored facial and unrestored lingual surfaces of the veneered teeth. A moderate correlation (r=0.407) was found between GCF and GI, which was significant at p<0.001. No correlation (r=0.124) was found between GCF and PPD, which was not significant at p=0.197.

CONCLUSIONS

Gingival response to the evaluated PLVs was in the satisfactory range, with overall GI scores ranging between normal and moderate inflammation, pocket depths ranging from 1 to 2 mm, and recession present in 27% of the evaluated PLVs. No statistically significant difference was found between the mean pocket depths of the restored and unrestored surfaces of veneered teeth (p≥0.136). A moderate correlation was found between GCF and GI.

Influence of restorative margins position on one-stage laser-microgrooved implants-supported single screwed crowns: A clinical, biochemical, and microbiological analysis

AIM

To clinically, biochemically, and microbiologically evaluate the influence of crown margins position on one-stage laser-microgrooved implants.

MATERIALS AND METHODS

Twenty-one-stage titanium implants with a laser-microgrooved collar surface, supporting screwed, single crown restorations, were placed in 20 partially edentulous patients and evaluated. Clinical parameters included modified plaque index, modified gingival index, peri-implant probing pocket depth, bleeding on probing, and distance between implant shoulder and mucosal margin. The parameters were recorded at baseline (crowns delivery) and at every 6-month recall visit, until the end of the 3 years follow-up period. At the same time intervals, radiographic marginal bone levels were assessed at the mesial and distal aspect of the implant sites. For biochemical analysis, the volume of the peri-implant sulcus fluid, and its levels of interleukin-1beta (IL-1β), interleukin-6 (IL-6), and of tumor necrosis factor-α, were utilized to evaluate the peri-implant health conditions at the end of the 3-year follow-up period. At the same time, microbiological analysis, including the concentration of five putative periodontal pathogens (Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Treponema denticola, and Tannerella forsythensis), were assessed. The crown margins positions were classified into four groups (A = intracrevicular position >2 mm, B = intracrevicular position ≤2 mm/<1 mm, C = intracrevicular position ≤1 mm/<0 mm, and D = extracrevicular position), and the biochemical, and microbiological parameters were evaluated at 3 years.

RESULTS

No statistical differences of clinical and biochemical parameters were found between the four groups. In group A, compared to groups B, C, and D, a statistically significant higher concentration of putative periodontal pathogens was found.

CONCLUSIONS

Results showed that the intracrevicular deeper position of the restoration margin does not influence the clinical and biochemical peri-implant parameters. The deeper position of the crown margin is associated with a greater amount of putative periodontal pathogenic microflora colonization.

Multidisciplinary full-mouth rehabilitation with soft tissue regeneration in the esthetic zone

OBJECTIVE

Oral rehabilitation often requires a multidisciplinary approach including restorative dentistry, prosthodontics, and periodontology to fulfill high esthetic and functional demands, frequently combined with changes in the vertical dimension. The presence of gingival recessions can be associated with numerous factors, such as brushing or preparation trauma and persistent inflammation of the gingiva due to inadequate marginal fit of restorations. Because gingival recessions can cause major esthetic and functional problems, obtaining stability of the gingival tissue around prosthetic restorations is of essential concern. Modifications of the occlusal vertical dimension require sufficient experience of the whole dental team. Especially in patients with functional problems and craniomandibular dysfunction, a newly defined occlusal position should be adequately tested and possibly adjusted.

CLINICAL CONSIDERATIONS

This case report presents a complete prosthetic rehabilitation combined with a periodontal surgical approach for a patient with gingival recessions and functional/esthetic related problems. The vertical dimension was carefully defined through long-term polymethyl methacrylate provisionals as a communication tool between all parts involved. All-ceramic crowns were inserted after periodontal healing as definitive rehabilitation.

CONCLUSIONS

Complex rehabilitation in patients with high esthetic demands including soft tissue corrections requires a multidisciplinary team approach that consists of periodontal surgeon, dentist and dental technician.

Aesthetic Crown Lengthening Using Chu Aesthetic Gauges And Evaluation of Biologic Width Healing

INTRODUCTION

The principles of biologic width have governed the literature and served as a clinical guideline during the evaluation of perio- restorative interrelationships. An adequate understanding of this concept is paramount to ensure adequate form, function, aesthetics and comfort of the dentition. Biologic width violation has become a common problem as most of the practitioners tend to underestimate the amount of tooth structure that must be exposed during a crown lengthening procedure. Also, adding to the confusion, there is a lack of general agreement regarding the amount of tooth structure that must be exposed above the crest of bone for restorative purposes.

AIM

The aim of this study was to perform aesthetic crown lengthening using Chu aesthetic gauges and evaluate the healing of biologic width.

MATERIALS AND METHODS

A total of 90 teeth in 15 patients were included into the study of which 30 teeth required crown lengthening and 60 teeth shared a proximal surface with the experimental teeth. Aesthetic crown lengthening was performed using the Chu aesthetic gauges. Presurgical and intraoperative data were recorded at baseline, three and six months at six sites per tooth.

RESULTS

The computed data suggest that although the positional changes of the periodontal tissues stabilize by three months, the biologic width if adequate crown lengthening is carried out re-establishes itself by three months to the original vertical levels and further gets stabilized by six months.

CONCLUSION

A step by step approach to periodontal aesthetic crown lengthening using Chu aesthetic gauge can serve to be vital for successful, predictable, and aesthetic restorative outcome.

Fixed dental prostheses with vertical tooth preparations without finish lines: A report of two patients

Tooth abutments can be prepared to receive fixed dental prostheses with different types of finish lines. The literature reports different complications arising from tooth preparation techniques, including gingival recession. Vertical preparation without a finish line is a technique whereby the abutments are prepared by introducing a diamond rotary instrument into the sulcus to eliminate the cementoenamel junction and to create a new prosthetic cementoenamel junction determined by the prosthetic margin. This article describes 2 patients whose dental abutments were prepared to receive ceramic restorations using vertical preparation without a finish line.

Periodontal response to two different subgingival restorative margin designs: a 12-month randomized clinical trial

OBJECTIVES

Subgingival margin placement is sometimes required due to different reasons and is often associated with adverse periodontal reactions. The purpose of this study was to determine if a single restoration with subgingival margin on a tooth, in the maxillary anterior zone, would affect its periodontal soft tissue parameters, and whether or not a deep chamfer preparation has a different influence in the periodontium when compared to a feather edge preparation.

MATERIAL AND METHODS

Plaque and gingival indexes, periodontal probing depth, bleeding on probing, and patient's biotype were registered. One hundred six teeth were prepared with a deep chamfer, while 94 were prepared with a feather edge finishing line. Twelve months after the restoration delivery, the same parameters were evaluated. Repeated measure one-way analysis of variance (ANOVA) (α = 0.05) was used.

RESULTS

A statistically significant difference between the baseline and the 12-month follow-up is present in regard to plaque index, gingival index, and periodontal probing depth, but no statistically significant difference between chamfer and feather edge finishing lines. There is a statistically significant difference between the baseline and the 12-month follow-up in regard to bleeding on probing. Feather edge preparation presents significantly more bleeding on probing and less gingival recession than the chamfer.

CONCLUSIONS

Subgingival margins do influence the periodontal soft tissue response. Statistically significant difference exists between feather edge and chamfer finishing lines in regard to bleeding on probing and gingival recession.

CLINICAL RELEVANCE

Subgingival margins should be carefully selected, especially when feather edge finishing line is utilized.

Effect of preparation surface area on the clinical outcome of full veneer crowns in dogs

Crown therapy is commonly used in veterinary medicine to provide support to teeth which have previously fractured, received root canal therapy, have significant wear, or experienced other detrimental removal of tooth substance. As with several aspects of veterinary medicine, many of the recommendations or guidelines for crown therapy originate from human dentistry, which are then transferred to veterinary patients. Due to the significant difference in the anatomy of teeth and function of the oral cavity between humans and dogs, these guidelines need to be studied to determine the appropriateness of their use in veterinary patients. This article evaluates the relationship between surface area of the preparation and clinical outcome of full veneer crown therapy of the canine tooth in dogs. Although there appeared to be a positive relationship between preparations with greater surface area and successful clinical outcome, it was not found to be statistically significant.

Crown preparation design: an evidence-based review

Evidence-based clinical guidelines for full metal crown preparation design are seldom encountered in the veterinary literature. The veterinary literature regarding prosthodontic treatment in companion animals is sparse and consists primarily of case reports and expert opinion based primarily on clinical experience. The goal of this manuscript is to present concepts of evidence-based practice, review common recommendations on crown preparation design from the veterinary literature, and to provide an assessment of the evidence for or against those recommendations.

Gingival displacement for impression making in fixed prosthodontics: contemporary principles, materials, and techniques

The clinical success and longevity of indirect restorations depend on the careful and accurate completion of several procedures. One of the challenging procedures is management of the gingival tissues and gingival esthetics. The goal for management of gingival tissues and gingival esthetics is to maintain the normal appearance of healthy gingival. Achieving this goal requires optimal health before treatment and minimal trauma during treatment. The best way of optimizing health and minimizing trauma is to avoid contacting the gingiva with restorative materials.

Biologic perspectives in restorative treatment

One of the primary goals of a long term successful restorative therapy is to establish a physiologic periodontal climate that facilitates the maintenance of periodontal health. The contemporary clinician has a host of alternatives for the restoration of teeth. It is now possible to mimic nature and provide restorations that defy detection but the most challenging procedure in clinical dentistry is fabricating a restoration in gingival harmony. Periodontal health is the basis of all restorative dentistry. Because periodontal disease is a major cause of tooth loss in adults, the clinician must be aware of the biological variables relevant to restorative therapy, basic concepts and clinical modes of therapy available, to be able to develop an appropriate diagnosis and treatment plan. A natural looking prosthesis within a healthy periodontium should represent the ultimate goal. This article addresses the interactions between periodontal tissues and restorative procedures. It reviews the essentials of soft tissue management inherent in restorative dentistry that will increase the probability of a successful restoration.

Biologic Width: Evaluation and Correction of its Violation

The concept of Biologic Width has been widely described by periodontists and restorative dentists. An adequate understanding of relationship between periodontal tissues and restorative dentistry is paramount to ensure adequate form, function and esthetics, and comfort of the dentition. While most clinicians are aware of this important relationship, uncertainty remains regarding specific concepts such as biologic width and indications and applications of surgical crown lengthening. These violations lead to complications like gingival inflammation, alveolar bone loss and improper fit of the restorative component. An attempt has been made in this article to discuss the concept of biologic width, its importance in maintaining a long term dental restoration including crown & bridge and implants, and the implications of biologic width violation. Lastly, we discuss the possible methods to assess biologic width and surgical & non-surgical corrective procedures.

Effects of glass ionomer and microfilled composite subgingival restorations on periodontal tissue and subgingival biofilm: a 6-month evaluation

BACKGROUND

This 6-month study evaluated the effects of resin-modified glass-ionomer cement (RMGI) and microfilled composite (MC) subgingival restorations on periodontal tissues and subgingival biofilm.

METHODS

Fifty-four periodontally healthy patients were assigned as follows: group 1 (N = 18), root exposure (RE) without non-carious cervical lesions (NCCL) treated with coronally positioned flap (CPF); group 2 (N = 18), RE with NCCL treated RMGI restorations plus CPF; group 3 (N = 18), RE with NCCL treated with MC restorations plus CPF. Probing depth (PD), visible local plaque score (PL), and local bleeding on probing (BOP) were assessed at baseline and 6 months after surgeries. Restored and non-restored root recoverage (RR) was assessed at 6 months. Each experimental tooth was subgingivally sampled (baseline and 6 months) and analyzed by checkerboard DNA-DNA hybridization.

RESULTS

Clinical results showed no significant differences among the groups regarding PL, BOP, and PD at baseline and 6 months. The RR means were similar among the groups at 6 months. Intragroup analyses revealed that the proportions of 10 periodontopathogens decreased at 6 months for the control group. For the RMGI group, there was a significant decrease in the proportions of nine periodontopathogens. For the MC group, there was a significant increase in the proportions of Fusobacterium nucleatum polymorphum and Gemella morbillorum and a decrease in five periodontopathogens. Intergroup analyses showed an increase in the proportion of F. nucleatum polymorphum for the MC group.

CONCLUSIONS

In a 6-month evaluation, well-finished RMGI or MC subgingival restorations did not negatively affect periodontal health. Furthermore, RMGI seems to exert more positive effects on the subgingival biofilm composition than MC.

A Short-Term Clinical and Microbial Evaluation of Periodontal Therapy Associated With Amalgam Overhang Removal

BACKGROUND

This study evaluated the effect of periodontal therapy plus amalgam overhang removal (PT+AOR) on periodontal status and the presence of Actinobacillus actinomycetemcomitans and Streptococcus mutans and compared two microbiological sampling techniques.

METHODS

Molar teeth with Class II overhang restorations were selected as the test group, and homologous sound teeth were selected as the control group. Periodontal probing depth (PD), clinical attachment level (CAL), and plaque and gingival indices were measured, and restorations were evaluated using radiographs and clinical exploration at baseline (T1) and 90 days after PT+AOR (T2). Microbial samples were taken with dental floss and paper points at T1 and T2. S. mutans and A. actinomycetemcomitans were detected using culture and commercial kits.

RESULTS

Mean values of plaque and gingival indices did not show statistically significant differences between test and control teeth between T1 and T2. At T2, the mean CAL decreased among test teeth, and the number of test teeth positive for A. actinomycetemcomitans showed a decrease, whereas positive samples for S. mutans increased. At T1, an association between the two sampling techniques for both bacteria was found. At T2, dental floss presented low sensitivity values for A. actinomycetemcomitans, whereas paper points showed low sensitivity for S. mutans.

CONCLUSIONS

PT+AOR showed a beneficial effect on clinical parameters and a decrease of A. actinomycetemcomitans. At T1, both sampling techniques showed appropriate results. At T2, the use of paper points was a more sensitive sampling technique for isolate A. actinomycetemcomitans, whereas dental floss was found to be an alternative sampling method for isolate S. mutans.

Detection of localized tooth-related factors that predispose to periodontal infections

The primary goal of periodontal therapy is to produce an environment that is conducive to oral health. This is achieved by eliminating the subgingival infection and implementing supragingival plaque control measures designed to prevent the re-colonization of the sulcus. Local etiologic factors, as described above, my prevent the removal of subgingival plaque, and may even contribute to destruction of the periodontal tissues. Thus, it is crucial to be able to recognize and, when possible, eliminate any plaque-retentive factor that could contribute to disease progression. Iatrogenic factors such as subgingival margins, restorative overhangs, overcontoured restorations and unpolished surfaces can be altered. Similarly, cervical enamel projections, enamel pearls and, in certain instances, palatal grooves can be removed or recontoured to enable the patient to access the area for good plaque control. There are some things that we cannot alter. Anatomic anomalies, particularly in posterior teeth, cannot be changed. However, awareness of potential anatomic variations and early detection of them may be able to prevent future attachment loss.

Interactions between the gingiva and the margin of restorations

An adequate understanding of the relationship between periodontal tissues and restorative dentistry is paramount to ensure adequate form, function, esthetics, and comfort of the dentition. While most clinicians are aware of this important relationship, uncertainty remains regarding specific concepts such as the biologic width and indications and applications for surgical crown lengthening. This review discusses the concept of the biologic width and its relationship to periodontal health and restorative dentistry. The importance of restorative margin location, materials, and contours related to periodontal health is also addressed. The rationale and indications for surgical crown lengthening are elaborated. Particular surgical principles of crown lengthening are examined in detail.

Surgical crown lengthening: evaluation of the biological width

BACKGROUND

Previous surgical crown lengthening studies have investigated positional changes of the free gingival margin but not the biological width. Histological studies utilizing animal models have shown that postoperative crestal resorption allowed reestablishment of the biological width. However, very little work has been done in humans. Therefore, the purpose of this study was to evaluate the positional changes of the periodontal tissues, particularly the biological width, following surgical crown lengthening in human subjects.

METHODS

Twenty-three (23) patients who needed surgical crown lengthening to gain retention necessary for prosthetic treatment and/or to access caries, tooth fracture, or previous prosthetic margins entered the study. The following parameters were obtained from line angles of treated teeth (teeth requiring surgical crown lengthening) and adjacent teeth with adjacent and non-adjacent sites: plaque and gingival indexes, free gingival margin, probing depth, attachment level, bone level, direct bone level, and biological width. During surgery, the bone level was reduced based on the future prosthetic margin and predetermined biological width; flaps were placed at the bony crest. Patients were examined at baseline and at 3 and 6 months postoperatively.

RESULTS

Eighteen patients completed the study. Overall, the amount of bone resected was 1 to 5 mm. At 90% of treated sites, > or = 3 mm of bone was removed. At 3 months, the apical displacement of the free gingival margin at non-adjacent, adjacent, and treated sites was 2.46 +/- 0.25 mm, 2.68 +/- 0.20 mm, and 3.07 +/- 0.16 mm, respectively. There was no significant change in the position of the free gingival margin from 3 to 6 months. The biological width at all sites was smaller at 3 and 6 months compared to baseline (P<0.05) except for the treated sites, which were not significantly different from baseline at 6 months.

CONCLUSIONS

During surgical crown lengthening, the bone level was lowered for placement of the prosthetic margin and reestablishment of the biological width. The biological width, at treated sites, was reestablished to its original vertical dimension by 6 months. In addition, a consistent 3 mm gain of coronal tooth structure was observed at the 3- and 6-month examinations.

Effect of posterior crown margin placement on gingival health

STATEMENT OF PROBLEM

The clinical impact of posterior crown margin placement on gingival health has not been thoroughly quantified.

PURPOSE

This study evaluated the effect of posterior crown margin placement with multivariate analysis.

MATERIAL AND METHODS

Ten general dentists reviewed 240 patients with 480 metal-ceramic crowns in a prospective clinical trial. The alloy was randomly selected from 2 high gold, 1 low gold, and 1 palladium alloy. Variables were the alloy used, oral hygiene index score before treatment, location of crown margins at baseline, and plaque index and sulcus bleeding index scores recorded for restored and control teeth after 1 year. The effect of crown margin placement on sulcular bleeding and plaque accumulation was analyzed with regression models (P<.05).

RESULTS

The probability of plaque at 1 year increased with increasing oral hygiene index score before treatment. The lingual surfaces demonstrated the highest probability of plaque. The risk of bleeding at intrasulcular posterior crown margins was approximately twice that at supragingival margins. Poor oral hygiene before treatment and plaque also were associated with sulcular bleeding. Facial sites exhibited a lower probability of sulcular bleeding than lingual surfaces. Type of alloy did not influence sulcular bleeding.

CONCLUSION

In this study, placement of crown margins was one of several parameters that affected gingival health.

Restitution of maxillary anterior aesthetics with all-ceramic components

This paper discusses the use of four types of ceramics; zirconia, leucite reinforced glass, densely-sintered pure aluminium oxide and a low fusing porcelain, for the restitution of anterior aesthetics. Recent advances in dental ceramic technology have made this scenario a reality, which only a decade ago, was thought elusive. While ceramics offer obvious advantageous properties of enhanced appearance, they also need to satisfy functional and longevity criteria to be considered viable restorative materials. Numerous studies have cited data to fulfil these criteria, including sustained function and survival rates similar to porcelain fused to metal (PFM) restorations. This discussion will focus on current dental ceramic advances, and present a clinical case study using all ceramic constituents to rectify a deteriorating dentition.

Effect of pH on endotoxin affinity for metal-ceramic alloys

STATEMENT OF PROBLEM

Crevicular pH may modify bacterial endotoxin affinity for high-noble metal-ceramic alloys.

PURPOSE

Porphyromonas gingivalis lipopolysaccharide (LPS) affinity for 3 metal-ceramic alloys at 3 different pH levels was compared in vitro by measuring adsorption to and release from the alloy surface.

MATERIAL AND METHODS

Metallographically polished disks were fabricated from Pd-Ag-Sn, Au-Pd-Ag-Sn-In, and Au-Pd-In-Ga alloys. Clean disks were placed individually into 1 mL at pH 6.5, 7.0, or 7.5 phosphate-buffered saline solution containing 0.9 endotoxin units per square millimeter tritiated LPS (n = 3 disks per alloy-pH group). The disks were incubated for 24 hours at 37 degrees C before being transferred to LPS-free buffer and incubated, again for 24 hours at 37 degrees C, to evaluate elution. This transfer continued at 24-hour intervals up to 96 hours total elution incubation. Lipopolysaccharide adsorption to and elution from disks was determined through liquid scintillation spectrometry. Adsorption data were evaluated with a 2-way analysis of variance (alpha=.05) and the post hoc Tukey honestly significant difference test.

RESULTS

Lipopolysaccharide adsorption values ranged from 0.48 +/- 0.04 EU/mm(2) for the Au-Pd-Ag-Sn-In alloy at pH 7.5 to 0.75 +/- 0.04 EU/mm(2) for the Pd-Ag-Sn alloy at pH 6.5. Alloy type (P=.0001) and environmental pH (P=.0001) significantly influenced adsorption. Adsorption to the Pd-Ag-Sn and Au-Pd-In-Ga alloys at pH 6.5, 7.0, and 7.5 were similar and decreased with increasing pH. In contrast, adsorption to the Au-Pd-Ag-Sn-In alloy was significantly less than to other alloys at pH 6.5 but did not differ at other pH levels. Lipopolysaccharide release from the alloy surface could not be detected.

CONCLUSION

P. gingivalis LPS affinity for metal-ceramic alloys was modified by environmental pH. The degree of LPS adsorption depended on the composition and surface chemistry of each alloy.

Ceramometal bonded inlays and onlays

Porcelain-fused-to-metal (PFM) is presently the most popular crown and bridge technique. Its success is attributable to the use of a metal substructure to support the porcelain, resulting in good esthetics, limited ceramic flexure, and better longevity than all-porcelain restorations. A new concept suggests encapsulating the metal substructure with ceramic and placing the insert under the occlusal surface, thereby combining the best properties of the esthetics of porcelain and the support of metal to achieve improved restorations.

Periodontal tissue responses after insertion of artificial crowns and fixed partial dentures

PURPOSE

The purpose of this review was, first, to critically evaluate published evidence on the effects of artificial crowns and fixed partial dentures (FPDs) on adjacent periodontal tissue health, and second to synthesize this evidence into meaningful summaries. Restoration qualities that contribute to inflammatory responses were identified based on strength of evidence, and variables that should be controlled in future investigations were outlined. Such information is necessary to accurately predict the prognosis of periodontal tissues adjacent to crowns or FPDs.

METHODS

Clinical trial and epidemiologic evidence published in English was collected. The effects of crowns or FPDs on gingival inflammation, probing depths, and bone loss were evaluated based on accuracy of measurement, reliability of measurement, and/or appropriateness of data analysis.

RESULTS

Crowns and FPDs increased the incidence of advanced gingival inflammation adjacent to restorations, particularly if restorations had intracrevicular finish line placement, poor marginal adaptation, or rough surfaces. However, because of the limitation in the accuracy and reliability of probing depth measurements, reports of greater mean probing depths of crowned teeth, which tended to be less than 1 mm greater than control teeth, should be questioned. Finally, crowns and FPDs in general did not accelerate the rate of adjacent bone loss.

CONCLUSION

Clinically deficient restorations, as well as clinically acceptable restorations, can contribute to gingival inflammation. However, with the limitations of the applied methods of measurement, current evidence has not shown an increased attachment loss adjacent to crowns or FPDs. Future trials should document periodontal health before therapy and periodically after restoration insertion so that each tooth serves as its own control. In future studies, the periodontal disease history of the patient, the influence of the restoration on plaque formation, and the composition of the crevicular microflora must be recorded.

Establishing the gingival emergence profile of restorations by using a resilient gingival replica

All references to gingival morphology are destroyed once the die is trimmed during construction of crowns, onlays, or veneers. The need for reconstruction of a gingival replica to assist in the reproduction of a restoration's gingival contour and emergence profile is discussed. A simple, practical approach to duplicate the natural sulcus and free gingival morphology with currently available materials is presented. The advantages and limitations of implementing this technique and its multiple uses in prosthodontic and implant reconstructions and implant cases are presented.

Single tooth replacement--expanded treatment options

The aim of any prosthesis is to restore function and aesthetics by replacing the missing tooth with minimal risks to adjacent tissues. The options presently available to the patient for the replacement of a missing single tooth include the removable partial denture, partial and full coverage bridgework, resin-bonded bridgework and the single-tooth implant prosthesis. The relative merits and guidelines for successful application of these treatment modalities are presented.

Oral hygiene, periodontal conditions and carious lesions in patients treated with dental bridges. A 15-year clinical and radiographic follow-up study

A longitudinal study, extending over a period of 15 years, was carried out in a group of 102 patients who received 108 bridges made by the senior students at the Dental Faculty, University of Oslo, in 1967/68. The study included 343 abutment teeth, and the remaining teeth in the same jaw which received the restoration, 525 in all, served as control. The oral hygiene, gingival condition, pocket depth, caries on crowned teeth, location of crown margins and changes of alveolar bone level were recorded during the study. During the first 10 years, the patients received oral hygiene prophylaxis every 6 months. The mean age of the patients at the beginning of the study was 48 years. Of the original group of 102 patients, 88 attended the clinical examination after 5 years, 71 after 10 years, and 55 after 15 years. The amount of plaque did not differ between the crowned teeth and the control teeth during the observation period, while GI score 2 and 3 was more frequent in crowned teeth than in the control teeth during this period. This was mainly observed when the crown margins were located sub-gingivally. A slight increase in mean pocket depth was recorded in the crowned teeth while the mean pocket depth for the control teeth remained at the same level during the 15 years. Caries lesions were recorded in 3.3% of the abutment tooth surfaces at the 5th year, in 10.0% at the 10th year and in 12.0% at the 15th year examination. No statistical differences in bone loss could be detected between the control teeth and the crowned teeth.

Periodontal effects of fixed partial denture retainer margins: configuration and location

Our purpose was to study the periodontal response to posterior fixed partial denture (FPD) retainers with different marginal configurations and locations. One posterior proximal site restored with a clinically acceptable FPD and one matched, unrestored posterior proximal site were examined in 60 subjects. Assessments were made of the FPD retainers and the periodontal responses to both the long-term and short-term use of these retainers. Periodontal examination included assessment of probing depth and bleeding on probing and determination of plaque index and the gingival index scores. Statistical analysis showed that "clinically acceptable" FPDs, which had clinically detectable deviations from an ideal (flat) retainer/tooth configuration, were not associated with increased probing depth or bleeding on probing when compared to the matched, unrestored teeth at both examinations. As a group, sites adjacent to subgingival retainer margins were not associated with greater probing depths than sites adjacent to supragingival retainer margins. These findings suggest that long-term exposure to variations of FPD margin configuration and location, within clinically acceptable but less than ideal parameters, are not associated with the destruction of the supporting periodontal tissues.

Patient maintenance of esthetic restorations

There are probably as many ways to maintain esthetic restorations as there are restorations. After esthetic treatment is completed, schedule a mandatory postoperative appointment to make certain that whatever technique the patient uses is effective. At the postoperative visit, it should be apparent that the patient's tissue is healthy. If the tissue has not healed, some change in home care or additional periodontal or restorative treatment may be necessary. There are virtually hundreds, perhaps even thousands of home plaque removal devices. The ones mentioned here have worked for us and are therefore discussed. It isn't the type of device that is critical, however, but patient compliance. The described regimens have worked effectively for us in overcoming this obstacle of compliance. Appropriate recall visits with the hygienist should be made at one- to six-month intervals. In the final analysis, your success with esthetic restorations may well depend on your patients' success with esthetic maintenance.

Restorative margin placement and periodontal health

Subgingival restorative margins are associated with the development of plaque-related inflammatory periodontal disease, primarily because of a shift in the subgingival microflora from a profile associated with health to one associated with disease. The degree and extent of the marginal inflammation is influenced by four factors: failure to maintain proper emergence profile, inability to adequately finish and/or close subgingival margins, placement of subgingival margins in an area with minimum to no attached gingiva, and violation of the biologic width. Supragingival margin placement is the location of choice for all restorative margins to avoid iatrogenic periodontal disease. However, consideration of these four factors will help reduce the adverse impact of restorative margins that must be carried subgingivally.

Periodontal margin in the older adult: considerations for position, placement, and support

Some of the oral health problems of older adults arise from loss of function, which is catalyzed by changes in oral health induced by systemic disease and its treatment. The successful maintenance of a healthy gingival to root surface interface depends on the development of appropriate dental and gingival contours to facilitate self-cleansing and proper hygiene procedures by the patient. This article, with the use of case histories, discusses only one of the complications to restorative care in older adults, that is, loss of function and its relationship to marginal placement. Prevention of oral disease in the older adult may require modification of the long-held periodontal/restorative philosophy of placing margins above the tissue wherever possible. In addition, the professional prophylaxis of restorations adjacent to the gingival margin must address the problems of the creation of a roughened surface by abrasion to composites from pastes and polishing.

Gingival enhancement in fixed prosthodontics. Part II: Microbiologic findings

This study assessed the changes of the subgingival/marginal microflora during fixed prosthodontic procedures and evaluated the effect of adjunctive rinsing with 0.12% chlorhexidine on the subgingival/marginal microflora during fixed prosthodontic treatment. Thirty patients scheduled for fixed prosthodontics were randomly assigned to either rinsing with 15 ml of tap water b.i.d. (control) or rinsing with 15 ml of 0.12% chlorhexidine gluconate b.i.d. (experimental). Subgingival and marginal plaque was analyzed at baseline, before crown preparation (2 weeks), before crown cementation (5 weeks), and 2 weeks after cementation (7 weeks). The fixed prosthodontic procedures alone altered the subgingival and marginal microbiota toward a more health-associated flora. Adjunctive rinsing twice daily with 0.12% chlorhexidine had a significantly greater effect in reducing putative periodontal pathogens compared with the control regimen. This medication was a useful adjunct to regular oral hygiene during fixed prosthodontic procedures by permitting the establishment and maintenance of a microflora compatible with periodontal health.

Periodontal conditions following treatment with distally extending cantilever bridges or removable partial dentures in elderly patients. A 5-year study

The aim of the present study was to evaluate the periodontal conditions following treatment with distally extending cantilever bridges or removable partial dentures (RPDs) in elderly patients. All participants had a complete denture in the maxilla and moderate-to-advanced bone loss around the teeth present in the mandible. After undergoing periodontal treatment, 27 patients were treated with distally extending cantilever bridges and 25 patients with a RPD. During the first 2 years following prosthetic treatment, the patients were recalled twice a year and during the last 3 years once a year for oral prophylaxis and assessment of the periodontal status. The patients treated with a RPD showed higher mean Plaque and Gingival Indexes than the patients treated with cantilever bridges. No change in probing pocket depths was observed in either group, and only a small decrease in radiographic alveolar bone height was revealed. In conclusion, only minor changes in the periodontal conditions were recorded during the 5 years of observation after treatment with cantilever bridges or RPDs.

Clinical precision of paralleling instruments

A method for measuring pin- or pinhole-deviation was developed and tested on nine consecutive bridge cases with parallel pin retention, in order to assess paralleling precision of guiding instruments used clinically. Measurements were performed on rubber base impressions including pinholes, involving the use of a stereomicroscope. The maximum pinhole error angle for the bridges investigated ranged between 5.9 and 16.1 degrees. The corresponding interval for abutments was 1.3-10.8 degrees. The experimental observations concerning the rather large values for the greatest pinhole deviation of fitting bridges could be satisfactorily explained theoretically. The results indicated that the magnitude of the largest permissible angular deviation for a restoration with parallel pin retention was significantly larger than that previously presented in the literature. Compared with results from a previously performed model study carried out during ideal preparatory conditions, the current investigation suggested that the paralleling precision of guiding instruments used clinically in fact decreases considerably, remaining, however, at an acceptable level.