Effect of apical root resection, orthodontic extrusion, and surgical crown lengthening on load capability.

OBJECTIVES: This study aims to investigate the load-to-fracture of procedures changing crown-to-root ratio (RCRR) aimed to restore severely damaged upper central incisors to avoid tooth extraction compared to implant placement. There is no evidence on load capability after apical root resection (AR), orthodontic extrusion (OE), and surgical crown lengthening (SCL) in respect to RCRR, respectively. MATERIAL AND METHODS: Human maxillary central incisors were endodontically treated, decoronated, and divided into 4 groups (n = 48). The following specimen preparation was performed: (I) adhesive core-and-post build-up (control), (II) as (I) and 2 mm apical root resection (AR), (III) before adhesive core-and-post build-up teeth were shortened 2 mm coronally (OE) (IV) as (I), but specimens were embedded 4 mm instead of 2 mm below the CEJ (SCL), group (V) implant-borne restoration with individual all-ceramic abutments (n = 12; ∅4.1/l = 12 mm) (IBR). All specimens received all-ceramic crowns, thermo-mechanical (TML), and subsequent linear loading (LL) until failure. RCRR were calculated and log-rank, Kruskal-Wallis, Mann-Whitney U, ANOVA, and chi-square tests applied (p = 0.05). RESULTS: Fracture loads after subsequent LL differed significantly (p = 0.001) between groups, while implants showed the highest values. Fmax median (min/max) were as follows: (I) 252 (204/542), (II) 293 (243/443), (III) 253 (183/371), (IV) 195 (140/274), and (V) 446 (370/539). Pair-wise comparison showed significant differences (p = 0.001) between group I/IV and group V, I, and IV (p = 0.045), II and IV (p = 0.001), and III compared to IV (p = 0.033), respectively. RCRR below 1 significantly increased load capability compared to RCRR = 1. CONCLUSIONS: OE appears to preferably ensure biomechanical stability of teeth that are endodontically treated and receive core-and-post and crown placement compared to SCL. AR has no adverse biomechanical impact. RCRR < 1 is biomechanically beneficial. CLINICAL RELEVANCE: For endodontically treated and restored teeth, orthodontic extrusion should be preferred compared to surgical crown lengthening prior single-crown restoration. As orthodontic extrusion, apical root resection has no adverse effect on load capability. Single-crown implant-borne restorations are most load capable.

Success rate of fractured teeth receiving modified crown lengthening surgery and restorations.

BACKGROUND: Whether to preserve a structurally compromised tooth or remove it is a dilemma often encountered by clinicians. The aim of this study was to assess the long-term success rate of fractured teeth preserved by modified crown lengthening surgery and restorations. METHODS: Thirty-nine patients with a total of 45 fractured teeth who had received modified crown lengthening surgery were recruited and examined. Numbers of teeth lost were recorded, and the criteria for successful teeth were defined. Kaplan-Meier estimator was used to determine the success rate. Possible risk factors were compared between successful and unsuccessful groups by a Cox regression analysis to explore the potential predictors of failure with a significant level at α = 0.05. RESULTS: The mean ± SD of success time without considering variants was 6.2 ± 0.6 years (95% CI 5.1-7.7). The mean survival rates ± SD at 1.0-, 2.0-, 3.0-, 5.0-, 7.0-, and 9.0-year intervals was 97.8 ± 2.2%, 92.2 ± 4.4%, 72.8 ± 7.9%, 68.2 ± 8.6%, 60.7 ± 10.5%, and 40.4 ± 13.6%, respectively. Failure cases in teeth with poor plaque control and step-shaped fracture margin were significantly more than those with good plaque control and knife-shaped fracture margin (HR = 7.237, p = 0.011; HR = 15.399, p = 0.006; respectively). CONCLUSIONS: Fractured teeth treated with modified crown lengthening surgery are anticipated to have a high clinical success rate for 6.2 ± 0.6 years. Plaque control and fracture morphology appeared to be significantly associated with the success of the multidisciplinary treatment approach.

An in vitro study evaluating the effect of ferrule design on the fracture resistance of endodontically treated mandibular premolars after simulated crown lengthening or forced eruption methods.

BACKGROUND: The purpose of this study was to evaluate the effect of ferrule design on the fracture resistance of endodontically treated mandibular first premolars after simulated crown lengthening and orthodontic forced eruption methods restored with a fiber post-and-core system. METHODS: Forty extracted and endodontically treated mandibular first premolars were decoronated to create lingual-to-buccal oblique residual root models, with a 2.0 mm height of the lingual dentine wall coronal to the cemento-enamel junction, and the height of buccal surface at the cemento-enamel junction. The roots were divided randomly into five equal groups. The control group had undergone incomplete ferrule preparation in the cervical root, with 0.0 mm buccal and 2.0 mm lingual ferrule lengths (Group F0). Simulated surgical crown lengthening method provided ferrule preparation of 1.0 mm (Group CL/F1) and 2.0 mm (Group CL/F2) on the buccal surface, with ferrule lengths of 3.0 mm and 4.0 mm on the lingual surface, respectively. Simulated orthodontic forced eruption method provided ferrule preparation of 1.0 mm (Group OE/F1) and 2.0 mm (Group OE/F2) on the buccal surface and ferrule lengths of 3.0 mm and 4.0 mm on the lingual surface, respectively. After restoration with a glass fiber post-and-core system and a cast Co-Cr alloy crown, each specimen was embedded in an acrylic resin block to a height on the root 2.0 mm from the apical surface of the crown margin and loaded to fracture at a 135° angle to its long axis in a universal testing machine. Data were analyzed statistically using two-way ANOVA with Tukey HSD tests and Fisher's test, with α = 0.05. RESULTS: Mean fracture loads (kN) for groups F0, CL/F1, CL/F2, OE/F1 and OE/F2 were as follows: 1.01 (S.D. = 0.26), 0.91 (0.29), 0.73 (0.19), 0.96 (0.25) and 0.76 (0.20), respectively. Two-way ANOVA revealed significant differences for the effect of ferrule lengths (P = 0.012) but no differences for the effect of cervical treatment methods (P = 0.699). The teeth with no buccal ferrule preparation in control group F0 had the highest fracture resistance. In contrast, the mean fracture loads for group CL/F2 with a 2.0-mm buccal and 4.0-mm lingual ferrule created by simulated crown lengthening method were lowest (P = 0.036). CONCLUSIONS: Increased apically complete ferrule preparation resulted in decreased fracture resistance of endodontically treated mandibular first premolars, regardless of whether surgical crown lengthening or orthodontic forced eruption methods been used.

The role of extracellular matrix metalloproteinase inducer glycosylation in regulating matrix metalloproteinases in periodontitis.

BACKGROUND AND OBJECTIVE: Extracellular matrix metalloproteinase inducer (EMMPRIN) is a transmembrane glycoprotein that may induce activation of matrix metalloproteinases (MMPs) and lead to the destruction of periodontal tissue. The level of EMMPRIN glycosylation might be involved in this process. This study aims to investigate the role of EMMPRIN glycosylation in regulating MMP-2 and MMP-9 during the progression of periodontitis. MATERIAL AND METHODS: Gingival tissues were collected from patients with chronic periodontitis and from patients undergoing crown-lengthening procedures (healthy gingival tissue). Tissues were used for immunohistochemistry and double immunofluorescence. A human immortalized oral epithelial cell (HIOEC) line was stably transfected by an N-acetylglucosaminyltransferase-V (GnT-V) RNA interference (RNAi) lentivirus to suppress EMMPRIN glycosylation. Gene silence efficiency was detected by western blot, quantitative real-time PCR and immunofluorescence (IF) staining. An HIOEC/human gingival fibroblast (HGF) co-culture model and an individual culture model were used in this study. After exposure of cells to Porphyromonas gingivalis lipopolysaccharide (Pg. LPS), the expression of EMMPRIN, MMP-2 and MMP-9 were assessed by western blot, quantitative real-time PCR and IF, and the secretion of MMP-2 and MMP-9 were detected by gelatin-degradation assays. RESULTS: Compared with the periodontally healthy group, patients with periodontitis showed increased expression of EMMPRIN on the gingival epithelial cell membrane. GnT-V, a key regulator of EMMPRIN glycosylation, was co-expressed with EMMPRIN in gingival epithelial cells in patients with periodontitis. Knockdown of GnT-V reduced the level of EMMPRIN glycosylation in HIOECs. Furthermore, in the HIOEC/HGF co-culture model, stimulation with Pg. LPS (10 µg/mL, 4 hours) promoted EMMPRIN glycosylation and increased the activities of MMP-2 and MMP-9, while suppression of EMMPRIN glycosylation by GnT-V knockdown reduced the synthesis and activities of MMP-2 and MMP-9 under Pg. LPS stimulation. Moreover, the gelatin-degradation assay showed that inhibition of EMMPRIN glycosylation suppressed the Pg. LPS-induced degradation of gelatin in the co-culture model. CONCLUSION: We conclude that EMMPRIN glycosylation participates in the regulation of MMP-2 and MMP-9 production through mediating the interaction of HIOECs and HGFs. Inhibiting EMMPRIN glycosylation can reduce the activation of MMP-2 and MMP-9 and suppress the degradation of extracellular matrix (ECM) in the HIOEC/HGF co-culture model. Therefore, this study suggests that EMMPRIN glycosylation may affect the host immune-inflammatory response by regulating MMPs in periodontitis.

Effect of prophylactic administration of Novafen for periodontal surgery on postoperative pain relief.

Pain is a subjective feeling and one of the defense and alerting mechanisms of the body, which is distinguished from the body senses, including touch sensation and perception of heat, cold, pressure, etc. Pain, discomfort, and edema are very common after dental procedures, especially after periodontal surgeries, usually occurring during the first 24 hours after surgery; such pains are classified as medium to severe pains. Generally, medications are used to manage patients' pain and discomfort. One of the most commonly used medications for pain control is Ibuprofen, which is one of the NSAIDs and is a simple derivative of phenylpropionic acid. There is evidence that caffeine alone or in association with Acetaminophen, Ibuprofen, or Aspirin can increase their analgesic effects. Novafen is a new drug which consists of Acetaminophens, Ibuprofen and caffeine and has been marketed in Iran in recent years. 70 subjects referring to the Department of Oral and Maxillofacial Surgery, Tabriz Faculty of Dentistry, who were candidates for crown lengthening procedure, were randomly selected and included in the present study, based on inclusion and exclusion criteria. No significant differences were detected in pain severity between the two groups either clinically or statistically at 30-minutes postoperative interval. Pain, discomfort, and edema are very common after dental procedures, especially after periodontal surgeries. Such conditions usually occur during the first 24-hours postoperative interval and are considered moderate to severe pains. Although in the present study, the administration of Novafen before periodontal surgery resulted in the relief of postoperative pain, further studies are recommended on the subject, The administration of Novafen before periodontal surgeries resulted in pain relief after surgery.

[Long-term treatment outcome and influencing factors of teeth receiving modified crown lengthening].

Objective: To observe the long-term clinical treatment outcome and the influencing factors of the outcome for the teeth receiving modified crown lengthening surgery combined with root canal treatment and post-core crown restoration. To summarize the clinical guidelines of modified crown lengthening surgery in selection of indications and for mulation of treatment planning. Methods: Fifty-seven patients with a total of 67 teeth receiving modified crown lengthening surgery combined with root canal treatment and post-core crown restoration for at least a 6 months' follow-up period between July 2004 and July 2013 were recruited in this retrospective study by phone call interviews. The patients' clinical outcomes were evaluated by the combination of clinical examination, radiograph and questionnaire regarding patient-reported outcome of the last follow up (≥9 months post modified crown lengthening surgery and ≥6 months after definite crown restorations). All of the treated teeth were classified into two groups, group A (teeth with good clinical treatment outcome) and group B (teeth with poor clinical treatment outcome), based on the defined criteria including patients' satisfaction with the function and esthetics of the teeth and absence of periodontal, endodontic and prosthodontic complications. The potential influencing factors of clinical treatment outcome were also determined by Logistic regression analysis. Results: Vertical root fracture in 1 tooth was found on its periapical film and the tooth was deemed hopeless. Thus, the survival rate is 99% (66/67) for the multidisciplinary treatment approach. Seventy-two percent (48/67) of the teeth achieved good clinical treatment outcome and 28% (19/67) of the teeth developed one or several complications. In group B (teeth with poor clinical treatment), 16 out of teeth exhibited periodontal complications with bleeding on probing (BOP) positive mostly found. Logistic regression analysis demonstrated that plaque control (OR=21.392, P=0.014), edge form (OR=7.610, P=0.011), and smoking experience (OR=7.315, P=0.018) were the risk factors influencing the clinical treatment outcome of modified crown lengthening surgery combined with root canal treatment and post-core restoration. Conclusions: Modified crown lengthening surgery combined with root canal treatment and post-core restoration has a good and stable clinical effect in the observational time of 6-114 months. Plaque control, smoking status and edge form of the tooth appeared to be the influencing factors of this multidisciplinary treatment approach.

Cirugía de alargamiento coronal y toma de impresión definitiva en la misma cita: una alternativa en casos especiales. Reporte de veinte casos / Crown lengthening surgery and final impression during the same appointment: an alternative for special cases. Series of twenty cases

Propósito: Describir una serie de casos en los que, por diferentes motivos, se debió realizarcirugía de alargamiento coronal, preparación dental y toma de impresión definitiva en unacita en dientes pilares de rehabilitación con prótesis fija. Métodos: Se reportan veinte casosde pacientes que requirieron tratamiento de rehabilitación definitiva en un número corto decitas por motivos de discapacidad, dificultad en la apertura bucal, poco tiempo en la ciudad,enfermedad sistémica o aprehensión. Dichos pacientes se sometieron a cirugía de alargamientocoronal, preparación dental y toma de impresión definitiva en zonas no estéticas enuna sola cita. Cuando fue requerido, hubo tratamiento previo de endodoncia y elaboraciónde postes. Resultados: No hubo complicaciones posquirúrgicas diferentes a las de todacirugía periodontal, como inflamación, dolor o sangrado, entre los veinte casos tratados.Conclusión: No se presentaron complicaciones en ninguno de los casos tratados. Se proponeesta conducta clínica en casos en los cuales esté indicada una cirugía de alargamientocoronal, preparación dental y toma de impresión definitiva en la misma cita...

Purpose: To describe a series of cases that, for different reasons, required crown lengthening surgery, dental preparation, and definitive dental impression performed in thesame appointment on pillar teeth for fixed dental prosthesis. Methods: This study reports a series of 20 patients who required definitive rehabilitation treatment in a small numberof appointments due to disability, mouth opening shortness, short stay in town, medicalcondition, or apprehensiveness. Patients underwent crown lengthening surgery, dental preparation,and definitive dental impression in non-aesthetic areas in the same appointment.When it was necessary, root canal and restoration with posts were carried out. Results:There were not postsurgical complications other than the usual localized periodontal inflammation,pain, and bleeding. Conclusion: There were no complications in the treatedcases. This clinical approach is recommended in cases where crown lengthening surgery,dental preparation and definite dental impressions in the same appointment are indicated...

[A primary observation of the long-term effect of modified crown lengthening procedure].

OBJECTIVE: To observe the effect of modified surgical crown lengthening procedure and discuss the factors which could affect the periodontal health of the operated teeth. METHODS: Seventeen patients, a total of 20 teeth, who received the modified crown lengthening surgery were recruited in a retrospective study (1 - 6 years). The periodontal status of the operated teeth was compared with the adjacent and the contralateral natural teeth respectively. RESULTS: One out of seventeen patients appeared root fracture after surgery, one patient wasn't satisfied with the color of the molar's metal crown, other fifteen patients were satisfied with the esthetics and function of the teeth. The sites where probing depth was 4 mm just accounted for 4% (5/120) of the operated teeth, and the probing depth of the other sites was less than or equal to 3 mm. Although 83% (33/40) of buccal and lingual sites of the teeth exhibited various degrees of bleeding index, the periodontal indices of the operated teeth and the adjacent teeth. The position of the crown margin had a significantly negative correlation with the bleeding index (r = -0.742), and the plaque index was moderately correlated with the bleeding index (r = 0.480). CONCLUSIONS: The modified surgical crown lengthening indicated a good effect, which could be an alternative method to save the residual crown and root. The position of crown margin might be the main factor which influences the periodontal health of the teeth.

Fracture resistance after simulated crown lengthening and forced tooth eruption of endodontically-treated teeth restored with a fiber post-and-core system.

PURPOSE: To evaluate the effect of ferrule preparation length on the fracture resistance after simulated surgical crown lengthening and after forced tooth eruption of endodontically-treated teeth restored with a carbon fiber-reinforced post-and-core system. METHODS: 40 extracted endodontically-treated mandibular first premolars were decoronated 1.0 mm coronal to the buccal cemento-enamel junction. The teeth were divided randomly into five equal groups. The control group had no ferrule preparation (Group A). Simulated crown lengthening provided ferrule preparations of 1.0 mm (Group B) and 2.0 mm (Group C). Simulated forced tooth eruption provided ferrule preparations of 1.0 mm (Group D) and 2.0 mm (Group E). After restoration with a carbon fiber post-and-core system, each root was embedded in an acrylic resin block from 2.0 mm apical to the margins of a cast Ni-Cr alloy crown, and loaded at 150 degrees from the long axis in a universal testing machine at a crosshead speed of 1.0 mm/minute until fracture. Data were analyzed using ANOVA with Tukey HSD tests, and Fisher's exact test, with alpha = 0.05. RESULTS: Mean failure loads (kN) for Groups A, B, C, D and E were: 1.13 (SD = 0.15), 1.27 (0.18), 1.02 (0.11), 1.63 (0.14) and 1.92 (0.19), respectively. Significant differences were shown for the effects of treatment method and ferrule length, with significant interaction between these two sources of variation (P < 0.0001). Increased apical ferrule preparation lengths resulted in significantly increased fracture resistance for simulated forced tooth eruption (P < 0.0001), but not for simulated crown lengthening (P > or = 0.24).

Experimental surgical and orthodontic extrusion of teeth in dogs.

The purpose of this study was to evaluate histologically the root surfaces of teeth submitted to orthodontic and surgical extrusion procedures in a dog model. Eighteen adult male dogs, divided into six groups of three dogs each, were used in the study. Each animal underwent two procedures: rapid orthodontic extrusion and surgical extrusion of the maxillary lateral incisors. The animals were sacrificed to produce samples at 7, 14, 45, 90, 120, and 180 days after surgery for assessment of cross sections of the coronal, medial, and apical thirds of the treated teeth. At early time points, some active surface and inflammatory resorption was observed exclusively in the surgical extrusion group; however, samples collected at later times demonstrated functional repair of the resorption gaps in both groups. Ankylosis was observed as a minor event and was apparently of a transient nature in samples of the surgical extrusion group. The results demonstrate the importance of maintaining the periodontal ligament and cementum surface; both are vital for the prevention of root resorption. It may be postulated that orthodontic extrusion is more conservative and physiologic than surgical extrusion; however, the results showed that function was restored in both groups.

Crown lengthening surgery--indications and techniques.

UNLABELLED: Crown lengthening is a surgical procedure aimed at removal of periodontal tissue to increase the clinical crown height. As a restorative dentist using this technique of crown lengthening, one needs to have an understanding of biological width, indications, technique, as well as some possible limitations. The authors aim to discuss these concepts in order that the restorative dentist can use crown lengthening as part of an overall treatment plan in a controlled and predictable manner, taking into account biological factors. CLINICAL RELEVANCE: Today's restorative dentist faces an apparent increase in patients exhibiting toothwear that may result in shortened teeth, making crowning these teeth problematic. In addition, it is evident that patients are becoming more aware of the importance of a pleasing smile. This article discusses crown lengthening as one way in which the restorative dentist can address both clinical demands.

Migration following crown-lengthening procedure--a case report.

Periodontal surgery may be accompanied with some postoperative complications such as pain, swelling and sloughing, purulence or infection, transient bacteremia, nerve trauma, and hemorrhage. In general, a resective surgical intervention may implicate reduction in the attachment apparatus. Migration as a postoperative complication has never been addressed in the literature. This paper presents a case report detailing migration of a tooth, following a surgical preprosthetic clinical crown-lengthening procedure, which was repositioned using adjunctive orthodontics with a removable maxillary modified Hawley appliance. It is incumbent upon the dentist to examine meticulously the occlusal status of the teeth prior to a planned surgical intervention and to take measures preventing any possible tooth migration during the healing process. Failure to achieve occlusal and intra-arch stability may lead to undesired tooth movement in the arch postsurgery, affecting future prognosis and complicating any planned prosthetic work.

Crown lengthening in mandibular molars: a 5-year retrospective radiographic analysis.

BACKGROUND: Crown lengthening procedures are a significant part of the periodontist's armamentarium. In order to recreate the clinical space lost to caries or trauma necessary for prosthetic restoration, osseous surgery is often required. If the procedure is not carefully planned, it may result in furcation involvement of multirooted teeth. METHODS: Twenty-six subjects with 26 mandibular molar teeth requiring crown lengthening procedures prior to prosthetic crown placement were evaluated. Nineteen subjects with 24 prosthetic crowns on lower molars which had not undergone crown lengthening were included as control teeth. Bite-wing radiographs prior to surgery (for the test group) or placement of the crown (control group) and 5 years after completion of the prosthesis were compared and analyzed. RESULTS: Of the 26 test teeth, 10 teeth (38.5%) were found to have radiographic evidence of furcation involvement, whereas none of the control teeth developed furcation invasions. CONCLUSION: A critical distance from the furcation (CDF) of 4 mm was established as a landmark under which, if surgery was performed on mandibular molars, chances of furcation involvement in the future were very high.

Esthetic periodontal considerations in orthodontic treatment--the management of excessive gingival display.

This paper examines various esthetic periodontal considerations during orthodontic treatment. The management of excessive gingival display caused by altered passive eruption is reviewed, with emphasis on causes, recognition, diagnosis and surgical management of this problem. A case of orthodontic treatment of excessive gingival display associated with altered passive eruption of the maxillary incisors is reviewed to demonstrate appropriate management. With proper diagnosis, soft-tissue periodontal procedures after completion of orthodontic treatment can enhance the patient's final appearance.

Estudo das alteraçöes sagitais, verticais e transversais decorrentes da distalizaçäo dos molares superiores com o aparelho Pendulum / Study of tranversals and verticals, sagittal alterations following of the upper molars distalizations with the Pendulum appliance

Nessa pesquisa, foram estudados 32 pacientes, 23 do sexo feminino e 9 do masculino, leucodermas, brasileiros, naturais da cidade de Bauru, estado de Säo Paulo, com idade variando de 11 anos e 6 meses a 17 anos e 9 meses, idade média de 14 anos e 7 meses, portadores de más oclusöes de Classe II, 1ª divisäo de Angle e presença de todos os dentes permanentes de segundo a segundo molar do lado oposto. Todos os indivíduos selecionados receberam como mecanismo para a distalizaçäo dos molares superiores, o aparelho Pendulum de Hilgers, que foi empregado por um período de 5,87 meses. Foram feitas as telerradiografias em norma lateral convencional, lateral de 45§ e modelos de estudo, antes e depois das distalizaçöes dos molares superiores. Foram obtidas as medidas cefalométricas e as medidas dos modelos de estudo e as diferenças entre as médias iniciais e finais do experimentos foram submetidas ao teste estatístico de Wilcoxon para dados pareados. Essa avaliaçäo possibilitou verificar as alteraçöes esqueléticas e os efeitos da distalizaçäo sobre os molares, pré-molares, caninos e incisivos superiores. Com base nos resultados obtidos e na metodologia empregada, no que tange as alteraçöes esqueléticas e dentárias decorrentes da distalizaçäo de primeiros e segundos molares superiores com o aparelho Pendulum, julga-se lícito concluir que a força leve e contínua das molas distalizadoras do aparelho e o intervalo de tempo näo alteraram significativamente o posicionamento ântero-posterior da maxila e mandíbula. Observou-se uma taxa de distalizaçäo mensal dos molares de 1,06 mm e 1,07 mm, respectivamente para os lados direito e esquerdo. Essa distalizaçäo foi acompanhada da inclinaçäo distal das coroas dos molares que acarretou a rotaçäo mandibular no sentido horário, refletindo diretamente no aumento da altura facial ântero-inferior. O efeito recíproco do aparelho Pendulum sobre a unidade de ancoragem acarretou o movimento mesial dos primeiros e segundos pré-molares e dos caninos. Outro efeito negativo constatado foi o movimento vestibular dos incisivos superiores e a sua conseqüência para a alteraçäo no perfil facial. Associado a distalizaçäo dos molares superiores foi observado também alteraçöes verticais e transversais em molares, pré-molares e caninos