A Novel Prefabricated Grid for Guided Endodontic Microsurgery

Introduction

This study aimed to introduce a novel method using cone-beam computed tomographic (CBCT) imaging and prefabricated grids to guide apical access during endodontic microsurgery and to compare its accuracy with that of the nonguided method.

The effect of three different periodontal pre-treatment procedures on the success of telescopic removable partial dentures

In this prospective study, 120 teeth consisting of maxillary and mandibular canines and premolars were divided into three groups each containing 40 teeth. The teeth were assigned randomly in quadrants to three different periodontal treatment protocols. The first group was treated with professional prophylaxis only. The second group received additional deep scaling. With the third group, additional surgical periodontal flap surgery and scaling was performed. Both papillary bleeding index (PBI) and probing depth (PD) were evaluated before, during and after treatment. During the subsequent prosthetic treatment phase all teeth were then used as telescope abutments supporting a removable prosthesis. The documentation of the attachment level (AL) was then used as a clinical parameter. One year after the incorporation of telescopic removable partial dentures (RPDs), PD, PBI and AL were again evaluated. The resulting periodontal parameters were compared between the different groups using the general linear model (GLM) repeated measures and the Kruskal-Wallis test for non-parametric variables. Differences within the three treatment groups were determined using the t-test, e.g. the Wilcoxon test for dependent variables (P < 0.05). A significant decrease in inflammatory indices (PBI) was found for all types of periodontal treatment (P < 0.03 for all groups). Additionally, the reduction in PD was significant for all of the three groups (P < 0.001 for all groups). The greatest reduction in PD was observed in the group in which a surgical approach was used. Evaluation of the attachment level after the incorporation of the telescopic RPDs showed that tooth position did not influence the periodontal prognosis and that the use of telescopic RPDs exerted no ascertainable negative influence on the periodontium of the abutment teeth.     

Computer-assisted simulations in orthodontic diagnosis and the application of a new cone beam X-ray computed tomography

Computational simulations which include three-dimensional (3-D) image processing and biomechanical calculations should provide useful information to our research and orthodontic clinic as a clinical tool defined as 'thinking'. In this review, 1) biomechanical simulations applied to predict the mandibular growth; 2) mathematical models of virtual bone cells and 3) 3-D images and solid model simulations for surgical planning are introduced. In biomechanical simulation, biting force, electromyographic (EMG) activity and cephalograms of 32 subjects were applied. Computational results of mathematical model were compared with actual bone growth in a rat. Three-dimensional image and solid model of 14 patients were utilized for their treatment planning. From the results, several concepts of our simulations were confirmed: 1) reaction forces generated by masticatory muscles at the condyle control the direction of mandibular growth; 2) some mathematical models have the possibility to describe the process of bone growth; 3) 3-D image processing software and solid models are necessary for diagnosis and planning of orthognathic surgery. We also believe that the orthodontists can more accurately predict the affects of surgical procedures and orthodontic tooth movement using the new cone beam X-ray computed tomography (CT) (CB MercuRay; Hitachi Medico Technology, Tokyo, Japan) and its advanced application software.     

Microleakage of Diaket and amalgam in root-end cavities prepared using MicroMega sonic retro-prep tips

The in vitro sealing ability of the root-canal sealer Diaket when used as a root-end filling material was compared with that of amalgam using linear microleakage of Indian ink. Eight groups of 20 extracted teeth each were formed, plus 12 control teeth as follows: 1) root-end resection of 45° bevel, root-end cavity preparation with an 008 round bur, amalgam root-end filling; 2) 45° bevel, bur, Diaket; 3) 45° bevel, using a sonic retro-prep tip, amalgam; 4) 45° bevel, sonic, Diaket; 5) no bevel, bur, amalgam; 6) no bevel, bur, Diaket; 7) no bevel, sonic, amalgam; 8) no bevel, sonic, Diaket. Root-end cavity depths of 3 mm were prepared. Specimens were immersed in Indian ink for 2 weeks. The teeth were demineralized, rendered transparent and linear dye penetration recorded. Results showed that Diaket provided a superior seal to amalgam irrespective of the root-end preparation. The degree of bevel of the resected root-end did not influence leakage. Sonic instrumentation resulted in a larger root-end cavity than with burs.     

Lichen planus evoked by periodontal surgery

A case of Lichen Planus (LP) following periodontal surgery in a patient previously free of the disease is described. Genetic predisposition and lymphokine secretion stimulated by local trauma are suggested as a possible mechanism of the phenomenon. It is recommended that LP patients, especially those suffering from the erosive type, should be treated as conservatively as possible, minimizing the possibility of trauma to the oral tissues where local immunity may have been altered by a pathological process.     

Influence of smoking on the outcome of periodontal surgery

Abstract. The 5-year outcome following periodontal surgery was evaluated in 57 patients that had received regular maintenance care throughout the follow-up period. The study population included 20 smokers, 20 former smokers and 17 non-smokers in the age range 37–77 years. The clinical characteristics evaluated were supragingival plaque, gingival bleeding and pocket probing depth. The region assigned for surgery was, in addition, radiographically evaluated in terms of periodontal bone height. Furthermore, the occurrence of the periopathogens Actinobacillus actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg) and Prevotella intermedia (Pi) and the gingival crevicular fluid (GCF) levels of tumor necrosis factor alpha (TNF-α) were assessed at follow-up. Plaque index was 28.5% at baseline and 32.9% at follow-up, indicating a good standard of oral hygiene, and gingival bleeding 31.7% and 24.9%, respectively, suggesting a low to moderate level of gingival inflammation. In regions assigned for surgery, pocket probing depth decreased significantly from on average 5.6 mm to 4.3 mm ( p <0.0001) and periodontal bone height increased significantly from on average 62.5% to 67.5% ( p <0.0001). In terms of bone height, the outcome was less favorable among smokers compared with non-smokers. There was a predominance of smokers among patients exhibiting loss of bone height after the 5 years of maintenance. No significant associations were found between the therapeutical outcome and supragingival plaque or subgingival occurrence of periopathogens. The associations between GCF levels of TNF-α and probing depth and bone height were unclear, whereas the level of TNF-α was significantly elevated in smokers.     

Postoperative exposure of bioresorbable GTR membranes: effect on healing results

The goal of this investigation was to evaluate the effect of postoperative exposure of two different bioresorbable membranes on the guided tissue regeneration (GTR) healing results compared to nonexposed sites. In each of 25 patients one pair of contralateral intrabony lesions was treated either with polylactic acid (PLA) or polyglactin 910 (PG-910) membranes. Postoperative exposure occurred in 9 PLA and 13 PG-910 sites. Standardized clinical [papillary bleeding index (PBI), gingival recession (REC), probing pocket depth (PPD), probing attachment level (PAL)] and radiographic examinations (digital subtraction radiography) were performed immediately before (baseline) and 6 and 12 months postoperatively (p.o.). Subgingival bacterial samples from surgical sites were evaluated by culture at baseline, 6 weeks, and 6 and 12 months p.o. Six months after surgery the changes (Δ) of REC were significantly (P≤0.05) greater in exposed than in nonexposed sites, independently of the membrane material (median): exposed sites, ΔREC=–1 mm; nonexposed sites, ΔREC=0.0 mm. However, 12 months p.o. no significant differences were found due to a decrease in the initial recessions in exposed sites. Although a higher percentage of exposed than nonexposed sites harbored periodontal pathogens 6 weeks p.o. at the gingiva-faced membrane surface, membrane exposure did not have a significant negative effect on ΔPPD, ΔPAL, or radiographic bone density changes 6 and 12 months p.o. Both membranes showed significant gains in PAL and bone density in both exposed and nonexposed sites. In conclusion, this study demonstrates that with consistent infection control the postoperative exposure of PLA and PG-910 membranes has no significant negative effect on the regeneration outcome, although higher initial gingival recessions must be expected than in the nonexposed sites. However, in exposed sites plaque and infection control were clearly impeded by the rough, exposed membrane surfaces and by the initially negative gingival morphology. Received: 22 January 1997 / Accepted: 5 May 1997     

Extensive bleeding during surgical treatment for gingival overgrowth in a patient on haemodialysis--a case report and review of the literature

Before performing renal transplantation, a most important concern is to control any infection, including oral infections before transplantation. The bleeding diathesis of patients with uraemia is a significant clinical concern, especially when surgery is required. A 44-year-old female patient on haemodialysis was referred for evaluation of gingival overgrowth. The patient was planning a renal transplantation two months later. As the lesions were not considered successfully treatable before transplantation, a gingivectomy and teeth extraction was performed. In pre-operative examinations, an abnormal bleeding time was not detected and other coagulation tests were normal. Under general anaesthesia, 19 teeth were extracted and overgrown gingiva was removed. During the operation, extensive blood loss of 1650ml occurred and four units of concentrated red blood cells were transfused. This study suggests that patients with renal failure undergoing dental surgery require careful pre-surgical evaluation including assessment of their coagulation ability.     

Patterns of emergency maxillofacial referrals and provision of services

The rising number of maxillofacial injuries in the UK requires a reappraisal of emergency services within our specialty. Although the impact of a dedicated trauma list has been reported, it has not been widely embraced, and we know of few data that help to plan the number or timing of such lists. We designed a minimum dataset to collect information about referral, cause of emergency, assessment of patients, and outcome during 2003 and 2004. Theatre data were examined retrospectively to analyse operations during the same period. We conclude that to serve a population of 2.6 million a minimum of 8 emergency lists are required each week to deal with non-complex cases; this equates to 3 lists/million population. The lists should be concentrated at weekends and early in the week.     

高容血液稀释对正颌外科病人血液动力学和凝血功能的影响

目的 探讨术前急性高容量血液稀释对正颌外科病人血液动力学和凝血功能的影响，评估该方法临床应用的价值。方法 选择择期行正颌外科双颔手术的病人40例，随机分为ABCD四组，每组10例。A为贺斯实验组。术前输注6％羟乙基淀粉和乳酸林格液各占总量1／2，行急性高容血液稀释；B为贺斯对照组，用6％羟乙基淀粉和乳酸林格液补充术中丢失血液和体液；C为佳乐施实验组，术前输注4％琥珀酰明胶和乳酸林格液各占总量1／2，行急性高容血液稀释；D为佳乐施对照组，用4％琥珀酰明胶和乳酸林格液补充术中丢失血液和体液。四组病例术中均采用硝普钠控制性降压，平均动脉压（MAP）控制在50～60mmHg。实验组在插管后稀释前即刘（T0），稀释后手术开始前即刻（T1），手术结束即刻（T2），术后第一日8AM（T3）时；对照组在手术开始前即刻（T1），手术结束即刘（T2），术后第一日8AM（T3）时，记录RBC、HBG、HCT及凝血指标的变化，以及血液动力学的变化。结果 MAP：A、C组T1低于T0（P〈0．01）；T2高于T1（P〈0．01）。HR：A、C组T2高于T0、T1（P〈0．01）。RBC、HGB、HCT和PLT：A、C组T1低于T0（P〈0．01），T3升高超过T1且接近T0。结论 术前急性高容量血液稀释对正颌外科病人血液动力学的稳定影响小，能减少血液的丢失。贺斯与佳乐施两种胶体液均可引起部分凝血指标的改变，但二者均不影响凝血功能。可以作为正颌外科手术选择性应用的一种有效的辅助方法。