Effects of electrosurgery on the gingival attachment in rhesus monkeys

A Comparative Analysis of Post-Retraction Changes in Gingival Height after Conventional and Surgical Gingival Displacement: Rotary Curettage, Diode and Er:YAG Laser Troughing

The aim of the current article is to analyze and compare post-retraction gingival height changes resulting from six different types of gingival-displacement methods, encompassing both conventional and surgical approaches. The study involved a comparative analysis of 263 teeth (consisting of 128 front teeth, 69 premolars, and 66 molars) from 23 patients. For the investigation, three classic retraction methods were utilized, namely the single-cord technique, retraction paste Expasyl, and retraction paste Astringent. Additionally, three surgical techniques were employed, which included ceramic bur rotary curettage, Er:YAG laser troughing, and diode laser troughing. A randomized split-mouth design was implemented, and a significance level of 0.05 was used for the study. The recovery of the free gingival margin height was assessed on gypsum models that were scanned using an intraoral scanner during the first and second week after the retraction procedure. The results revealed that all retraction methods, except for ceramic bur rotary curettage, led to clinically insignificant levels of gingival recession. The article provides insights into the effectiveness and safety of various gingival-displacement techniques, highlighting that most methods tested in the study resulted in minimal or negligible gingival recession post-retraction.

Comparison of four cordless gingival displacement systems: A clinical study

STATEMENT OF PROBLEM

Although the conventional chemicomechanical cord technique is widely used, packing the cord into the sulcus may cause pain and bleeding. Cordless displacement techniques have been introduced, but a comparison of these systems is lacking.

PURPOSE

The purpose of this clinical study was to evaluate the efficiency and gingival response of 4 cordless gingival displacement systems.

MATERIAL AND METHODS

One hundred twenty teeth in 30 participants were allocated to 4 groups according to the material used: Tr (Traxodent; Premier Dental Products Co), Es (Expasyl; Acteon UK), Ez (Expazen; Acteon UK), and Mr (3M Retraction; 3M ESPE). Baseline measurements of periodontal indices and a digital scan were acquired. The cordless displacement pastes were applied according to the manufacturer's instructions. After removal, a second scan was acquired. Participants were recalled on the 2nd and 14th day to measure periodontal indices and for scans. Screenshots were superimposed to measure changes in the gingiva. Statistical differences among the different materials in achieving lingual and buccal vertical gingival displacement were tested using the related-samples Friedman 2-way ANOVA test by ranks at 3 time points such as immediate, at 2 days, and at 14 days (α=.05).

RESULTS

Immediate gingival displacement varied with the system used. For horizontal displacement, median values ranged between 150 μm (Tr) and 725 μm (Ez) for buccal displacement and between 93 μm (Tr) and 550 μm (Ez) for lingual displacement. Minimum and maximum displacements also varied and followed a similar trend, with Traxodent providing the lowest displacement. The plaque index and attachment level did not statistically differ before and after the treatment. The periodontal parameters were not statistically significant among the groups at all time intervals, except for the gingival index that increased for all the groups after 2 days.

CONCLUSIONS

Significant differences were found among the 4 tested systems in both vertical and horizontal gingival displacement. Expasyl, Expazen, and 3M Retraction exceeded the 200-μm requirements for horizontal displacement. Traxodent provided the least displacement in both vertical and horizontal dimensions.

Dental Impression Materials and Techniques

Dental impression making is the process of creating a negative form of the teeth and oral tissues, into which gypsum or other die materials can be processed to create working analogues. Contemporary dentistry generates new information every year and digital dentistry is becoming established and influential. Although dentists should stay abreast of new technologies, some of the conventional materials and time-tested techniques remain widely used. It is important to review the impression-making process to ensure that practitioners have up-to-date information about how to safely and effectively capture the exact form of the oral tissues to provide optimal patient management.

Gingival tissue healing following Er:YAG laser ablation compared to electrosurgery in rats

The erbium-doped yttrium aluminum garnet (Er:YAG) laser is currently used for periodontal soft tissue management with favorable outcomes. However, the process of wound healing after Er:YAG laser (ErL) treatment has not been fully elucidated yet. The aim of this study was to investigate the gingival tissue healing after ErL ablation in comparison with that after electrosurgery (ElS). Gingival defects were created in 28 rats by ablation with ErL irradiation or ElS. The chronological changes in wound healing were evaluated using histological, histometrical, and immunohistochemical analyses. The ErL-ablated gingival tissue revealed much less thermal damage, compared to the ElS. In the ElS sites, the postoperative tissue destruction continued due to thermal damage, while in the ErL sites, tissue degradation was limited and the defects were re-epithelialized early. Heat shock protein (Hsp) 72/73 expression was detected abundantly remote from the wound in the ElS, whereas it was slightly observed in close proximity to the wound in the ErL sites. Hsp47 expression was observed in the entire connective tissue early in the wound healing and was found limited in the wound area later. This phenomenon proceeded faster in the ErL sites than in the ElS sites. Expression of proliferating cell nuclear antigen (PCNA) persisted in the epithelial tissue for a longer period in the ElS than that in the ErL. The ErL results in faster and more favorable gingival wound healing compared to the ElS, suggesting that the ErL is a safe and suitable tool for periodontal soft tissue management.

Survey of Impression Materials and Techniques in Fixed Partial Dentures among the Practitioners in India

Objective. Anecdotal evidence suggests that impression materials and techniques used in general dental practice for fixed partial dentures vary from those taught in dental schools. The aim of this survey was to integrate impression techniques evolved all over the years for fixed partial dentures and to know the techniques and materials which are used in the present day by the practitioners. Materials and Methods. A total of 1000 questionnaires were sent to various practitioners in India, out of which 807 questionnaires were filled. Results. The results showed that 84.8% of prosthodontists (65.56%, urban areas) use elastomeric impression materials as well as irreversible hydrocolloids and 15.2% use irreversible hydrocolloid only. Amongst other practitioners, 55.46% use irreversible hydrocolloid (45%, rural and semiurban areas) and 44.54% use elastomeric impression materials. Elastomeric impression technique practiced most commonly is putty reline with/without spacer (77.2%); other techniques are multiple-mix and monophase techniques. Conclusion. The ideal materials, technique, and armamentarium are required for the long-term success of the treatment for fixed partial denture. Also, if the ideal procedure is not followed, it will lead to a compromised fit of the final prosthesis and failure of the treatment.

Long-term histologic analysis of bone tissue alteration and healing following Er:YAG laser irradiation compared to electrosurgery

BACKGROUND

The erbium-doped:yttrium, aluminum, and garnet (Er:YAG) laser is reportedly useful for periodontal therapy. However, the potential thermal damage that Er:YAG laser irradiation can produce on bone tissue has not been fully clarified. The purpose of this study was to histologically examine the effects of the Er:YAG laser on bone tissue and subsequent wound healing compared to electrosurgery in a long-term study.

METHODS

Calvarial bone from 30 rats was exposed to contact and non-contact Er:YAG laser irradiation (115 mJ/pulse, 10 Hz) without water coolant, or electrode contact. The treated surfaces were analyzed by scanning electron microscopy (SEM), and the healing process was histologically observed until 12 months post-surgery.

RESULTS

Contact irradiation resulted in substantial bone ablation, whereas non-contact irradiation produced slight tissue removal. Histologic and SEM analyses of the lased surface showed no severe thermal damage, except for the production of a superficially affected layer with a microstructured surface. The layer did not inhibit new bone formation, and the ablated defect was repaired uneventfully. Although the thickness of the layer gradually decreased, it generally remained in the cortical bone through the observation period. Electrosurgery produced a large area of thermal necrosis without ablation, and the damaged area was not replaced with new bone.

CONCLUSIONS

Unlike electrosurgery, Er:YAG laser irradiation without water coolant easily ablated bone tissue, and thermal alteration in the treated surface was minimal. The superficially affected layer did not interfere with the ensuing bone healing, resulting in favorable repair of the defect.

Gingival retraction techniques for implants versus teeth: current status

BACKGROUND

The authors reviewed and compared gingival retraction techniques used for implants and teeth.

TYPES OF STUDIES REVIEWED

The authors searched the literature using article databases Ovid MEDLINE up to May 2008, PubMED and Google Scholar (advanced search) and the following search terms: gingival retraction, implant abutment, impressions, cement-retained implant restoration, impression coping, peri-implant tissue, emergence profile and tissue conditioning.

RESULTS

The authors found insufficient evidence relating to gingival displacement techniques for impression making for implant dentistry. Gingival retraction techniques and materials are designed primarily for peridental applications; the authors considered their relevance to peri-implant applications and determined that further research and new product development are needed.

CLINICAL IMPLICATIONS

The use of injectable materials that form an expanding matrix to provide gingival retraction offers effective exposure of preparation finish lines and is suitable for conventional impression-making methods or computer-aided design/computer-aided manufacturing digital impressions in many situations. There are, however, limitations with any retraction technique, including injectable matrices, for situations in which clinicians place deep implants.

Periodontal considerations in restorative and implant therapy

The successful integration of periodontal and restorative dentistry for both natural teeth and implants requires knowledge and application of both mechanical and biological principles. In areas of aesthetic concern, an adequate band of attached gingiva can increase patient comfort, reduce the probability of gingival recession following tooth preparation and simplify restorative procedures. While some restorative margins need to be placed at or below the margin of the free gingiva, this should be considered to be a compromise, and margins should not be placed more than 0.5 mm into a healthy gingival sulcus. Approximately 2-3 mm of healthy, natural supra-alveolar tooth surface is needed for attachment of the gingival tissues to the tooth. This dimension is called the biological width. If adequate biological width does not exist, surgical or orthodontic procedures to expose healthy tooth structure are recommended before final restorations are placed. Retraction of soft tissues for impressions is best accomplished with mechanical methods rather than lasers or electrosurgery because of the potentially harmful effects of these devices to the cementum, bone and soft tissues surrounding the teeth. Implants function best and withstand occlusal forces optimally when loaded in a vertical direction. Therefore, planning implant placement is critical for success. Because of increased proprioception, it is suggested that natural teeth be used to guide the occlusion in partially edentulous patients. Cantilevers should be used with caution and with appropriate attention to occlusal forces. While occlusal trauma does not cause periodontal disease, it may contribute to bone loss around teeth and implants. In the opinion of the authors, provisional restorations are an integral part of dental and periodontal therapy. They can be used to establish aesthetic and physiological contours that can be easily cleaned by patients and they can also be used as a guide for any needed surgical tissue modification.

Tissue management with a new gingival retraction material: a preliminary clinical report

A new retraction material (Merocel) was evaluated in a clinical trial with 10 selected abutments. Each selected abutment required an anterior single unit. A comparison of probing attachment level, bleeding on probing, and plaque index demonstrated highly successful periodontal maintenance. The main advantage of Merocel retraction material is that it is capable of innocuously expanding the gingival sulcus. This preliminary study suggested that a Merocel strip was a predictable retraction material in conjunction with impression procedures. The material was also evaluated by scanning electron microscopy and demonstrated promise in this investigation. The Merocel strip shows potential for other applications, but limitations of this material indicated that evolution of atraumatic gingival retraction should continue.

Periodontics and prosthodontics: goals, objectives, and clinical reality

Prosthodontics and periodontics are collaborative disciplines. A successful prosthesis depends on a healthy periodontal environment, and periodontal health depends on the continued integrity of the prosthodontic restoration. To facilitate this collaboration, prosthodontists should not only appreciate the periodontic implications of gingival displacement procedures and tooth preparation, but should be knowledgeable about the types of gingival tissues, osseous topography, occlusal effects, and their implications for abutment choice. Working as a team, the periodontist can identify for the prosthodontist a patient's periodontal strengths and limitations. In that way, the prosthodontist can then assume responsibility for a given treatment plan based on a mutual understanding of the critical factors involved.

Lengthening clinical crowns

Finding a solution to the short clinical crown is based on an appreciation of the biological width of attachment plus the dimensional requirements of sound restorative procedures. The collective talents of restorative dentist, orthodontist, and periodontist often are needed to cope with the problem.

Comparison of electrosurgery with conventional fiberotomies on rotational relapse and gingival tissue in the dog

The relapse tendency of orthodontically rotated teeth after electrosurgical circumferential fiberotomies and after conventional scalpel blade surgical procedures was demonstrated with a split-mouth procedure involving the maxillary second incisors of five mongrel dogs. The second incisors were rotated orthodontically an average of 63.5 degrees over a 4-month period. Electrosurgical circumferential fiberotomies were performed on the designated second incisors, and circumferential fiberotomies with a scalpel blade were performed on the contralateral incisors. The teeth were retained for 1 month and relapse was measured 2 months postretention. Wound healing was demonstrated by measurement of sulcus depths and facial gingival recession preoperatively and at 1, 2, 3, 4, and 9 weeks after surgery. In both groups, the sulcus depths had decreased about 2 mm and the facial gingiva had receded 0.3 mm 9 weeks after surgery. Two months postretention there was an average 25% relapse in the teeth treated by means of a circumferential fiberotomy with a scalpel blade compared to an average 23% relapse in those treated by means of a circumferential fiberotomy with electrosurgery. No significant difference was seen between the two techniques.

Electrosurgery--a biological approach

Electrosurgery has been used in dentistry for more than 50 years. Both opponents and advocates of electrosurgery have presented a variety of clinical studies in favour of their respective opinions, which are discussed in the following review. In some studies, wounds created by electrosurgical techniques were observed through the healing stages, in comparison to those following incision by a surgical blade, with no significant difference being discovered. Other studies reported that the histologic response of oral connective tissue to electrosurgery was adverse in some animal and human models. However, neither of these groups used methods that allowed documentation or control of operating variables. A critical evaluation of controlled clinical studies shows that adverse responses of (connective) tissue, epithelium, bone, cementum, and periodontal attachment are related to an excessive lateral heat production during the procedure. With electrosurgery, the clinician can control the inherent variables. Waveform, frequency, size of the electrode, time of contact and cooling periods are some of those considered to be of importance in the studies. On the basis of the research reports, clinical guidelines have been developed to give practical advice to the clinician using electrosurgery. Providing that these safeguards are adhered to, scientific evidence supports the biological compatibility of electrosurgery for intraoral surgical procedures.

Tissue displacement methods in fixed prosthodontics

The various methods to accomplish gingival displacement have been described. The techniques have been noted and their relative advantages and disadvantages summarized. The practicing dentist can use this review to make better informed decisions regarding the method he or she chooses for the treatment of a particular patient.

Electrosurgery and wound healing: a review of the literature

This literature review and discussion has presented evidence that some additional research needs to be done in this area. Particular attention should be paid to control certain variables: kind and type of waveform, shape and size of electrode, and speed of the electrode through the tissue so that meaningful results may be given to the dental profession. The evaluation of the literature seems to show that when the variables are controlled, untoward results of wound healing after electrosurgery seem unwarranted.

Comparative study of gingival retraction methods

The effects of electrosurgery, retraction cord, and the rotary gingival curettage technique were tested clinically and histologically in dogs. Postoperative periods analyzed ranged from 6 hours to 14 days. All methods induced some kind of minor damage. Recession of clinical magnitude was induced only by rotary gingival curettage. Apical migration of the junctional epithelium was not seen.

Pulpal effects of electrosurgery involving based and unbased cervical amalgam restorations

The pulpal effects of electrosurgery involving unrestored enamel, cementum, calcium hydroxide-copal varnish-based restorations and unbased restorations were evaluated in extracted human teeth and posterior teeth of cynomolgus monkeys. Electrosurgery for all studies was performed with a fully rectified filtered unit under conditions of normal clinical usage. Studies in extracted human teeth measured the voltage potential generated between a reference probe in apical pulp tissue and an activated electrosurgery electrode placed on enamel, cementum, based restorations, and unbased restorations. Placement of a base reduced but did not prevent passage of electrosurgical current, and no measurable potential was associated with activated electrode contact on cementum or enamel. Studies in three cynomolgus monkeys included electrosurgery of based and unbased cervical silver amalgam restorations, electrosurgery of unrestored enamel, restored teeth not subjected to electrosurgery and teeth that were neither restored nor subjected to electrosurgery. Electrosurgery of restored teeth, regardless of the presence of a base, consistently resulted in pulpal damage characterized by an altered dentin matrix, necrosis adjacent to the cavity preparation, and a transition zone between necrotic and apparently vital pulp tissue. By 8 weeks following electrosurgery, the majority of specimens showed replacement of the odontoblastic layer and adjacent pulp tissue by dense connective tissue with areas of irregular calcification.

Effects of electrosurgery on dog pulps under cervical metallic restorations

Fifty-four Class V amalgam restorations were placed in nine beagle dogs to determine whether electrosurgical effects on pulp tissue could be altered by the presence of metallic restorations. An electrosurgical technique was performed, simulating clinical procedures for tissue removal while traversing the restorations. Time and power-use measurements were recorded for each operation. All operations that were performed within a time range imitating clinical procedures failed to produce changes in pulpal histology. When electrosurgical exposures were extended beyond 0.4 second contact with restorations, pulpal alterations occurred in the majority of specimens.

Healing of electrosurgical incisions in gingiva: early histologic observations in adult men

The healing of electrosurgical incisions in the gingivae of adult men was investigated at 6-hour intervals. Clinical observation indicated that incisions healed progressively until 72 hours, when they were barely discernible. Clinical evidence of inflammation associated with the wounds was negligible. At a light microscopic level, initial reaction to electrosurgical incisions included disruption of the surface epithelium and denaturation of the connective tissue lateral to the incision. The zone of denatured connective tissue remained for the entire 72-hour period of this study. Young fibroblasts and vascular proliferation were evident in the connective tissue at 30 hours. Epithelium exhibited complete bridging of the wound surface in some specimens as early as 30 hours after incision. All specimens had an intact epithelial surface at 48 hours. Mild-to-moderate accumulations of inflammatory cells, consisting primarily of lymphocytes, surrounded the wound edges. Acute inflammation with polymorphonuclear leukocytic infiltration was not observed, except for moderate accumulation at 6 to 12 hours. Subepithelial hematoma formation within the connective tissue was evident in four of the size specimens at 72 hours.

Effect of retraction procedures on the periodontium in humans

On the basis of wound healing and gingival recession caused by the three procedures, the copper-band retraction method was the most satisfactory. This tentative conclusion is based on the following reasons: 1. Retraction methods must be evaluated relative to the impression procedure and fit of the restoration. The long-range effects of the marginal fit are probably the most important factor for enhancing periodontal health. 2. This study involved only healthy periodontia of adolescent patients. Different healing might be observed in tissues characterized by gingivitis or periodontitis. 3. A broader study involving a greater range of procedures and conditions is recommended to evaluate each retraction technique. 4. This study involved teeth which had an adequate zone of attached gingiva. More complicated healing and perhaps altered sequences might be observed if the procedures were performed on gingival margins of alveolar mucosa, thin gingival walls, or areas of root prominence and thin cortical bone.

A method to measure operating variables in electrosurgery

Variables affecting tissue response to electrosurgical wounding have been identified and discussed. An electronic measuring device was designed and built to record actual power generated at the active electrode during surgical use of an electrosurgery instrument. In addition, this electronic device measures the amount of time the active electrode is in contact with tissue. Coupled with an electrosurgery unit producing a documented waveform and an electrosurgery electrode having a controlled-depth gauge, variables affecting tissue response to electrosurgery wounding may be measured.

Pulpal and periodontal effects of electrosurgery involving cervical metallic restorations

The pulpal and periodontal effects of electrosurgery involving teeth restored with Class V cervical amalgams and nonrestored teeth were evaluated in three cynomolgus monkeys. Electrosurgical current was delivered for 1 second with a fully rectified unit at an output intensity consistent with normal clinical usage. Experimental conditions included electrosurgery involving restored teeth, electrosurgery involving unrestored enamel, restored teeth not subjected to electrosurgery, and teeth which were neither restored nor subjected to electrosurgery. No pulpal or periodontal tissue changes were observed in the latter three groups of teeth. Electrosurgery involving cervical restorations consistently resulted in coagulation necrosis of the pulp and extensive resorption of cementum, dentin, and interradicular bone in the furcation area of multirooted teeth. The results suggest that inadvertent contact with cervical restorations during electrosurgical procedures may endanger both the pulp and the periodontal attachment apparatus.