Immediate implant placement in the anterior mandible: a cone beam computed tomography study.

BACKGROUND: The placement of implants into the alveolar socket right after tooth extraction is called immediate implant placement (IIP). This approach has its particularities depending on which region of the jaws is involved. The anterior mandible region is peculiar due to the presence of mandibular incisors, which have the shortest roots among all permanent teeth. PURPOSE: This study aimed to investigate the factors that could be associated with the risk of either cortical bone wall perforation or invasion of the 2 mm secure distance from the surrounding anatomical structures (defined as unsafe implant placement), with IIP in the maxillary aesthetic zone, in a cone-beam computed tomography (CBCT) virtual study. MATERIALS AND METHODS: CBCT exams from 239 eligible subjects were investigated. Implants were virtually placed in two distinct positions: prosthetically-driven (along the long axis of the existing tooth) and bone-driven position (according to the available bone and with regard to nearby anatomical structures). Correlation between several variables was tested, and binary logistic regression analysis in order to assess of the possible associations between covariates and unsafe placement was performed. RESULTS: Safe placing implants was significantly higher for the bone-driven in comparison to the prosthetically-driven position (22.2% vs. 3.3%, respectively), and the 2-mm secure distance from anatomical structures was not possible to respect in the majority of cases (77.6% vs. 82.9%, respectively). Covariates associated with a higher risk of unsafe placement were tooth region (CI in relation to IL and CA), decrease of labial concavity angle (LCA), decrease of mandible basal bone height (MBBH), and decrease in mandibular bone thickness at the tooth apex level (MBT0). CONCLUSION: The possibility of safely placing immediate implants in the anterior mandible is significantly higher for bone-driven than in prosthetically driven position. Presurgical virtual planning with CBCT is a great tool for minimizing the risk of implant unsafe placement with regards to the anatomical conditions in the mandible.

Endodontic guide for the conservative removal of a fiber-reinforced composite resin post.

Prosthetic dentistry involves functional and esthetic restoration. Some situations require the use of fiber-reinforced composite resin posts that help preserve restorations. However, if the initial treatment fails, a new endodontic intervention may be required for fiber-reinforced composite resin post removal. This procedure can be complex and challenging but can be facilitated with guided endodontics. This clinical report describes the use of a prototyped guide created with virtual planning for fiber-reinforced composite resin post removal. The guide improved patient safety, shortened the treatment time, and eliminated the need for a new restoration.

Limitations and Management of Static-guided Endodontics Failure.

Endodontic treatment in severely calcified canals is always a challenging task because it can result in accidents such as deviations or perforations. Recently, guided endodontics has become an alternative approach for pulp canal calcification, facilitating the location of root canals more predictably through the combined use of cone-beam computed tomographic imaging, oral scanning, and endodontic access guides. Although several reports have shown that guided endodontics is safer, faster and can be performed without an operating microscope and by less experienced operators, the technique has limitations, and iatrogenesis may occur. This article describes the limitations of static-guided endodontics and possible causes of failures. In the present case, not fixing the guide to the bone and inaccuracies generated by manually performing mesh merger software led to root perforation. Endodontic microsurgery was effective in resolving this case and should be considered the treatment of choice when guided endodontics cannot be used safely or when it fails.

Immediate Implant Placement in the Maxillary Aesthetic Zone: A Cone Beam Computed Tomography Study.

This study aimed to investigate the factors that could be associated with the risk of labial cortical bone wall perforation with immediate implant placement (IIP) in the maxillary aesthetic zone, in a cone-beam computed tomography (CBCT) virtual study. CBCT exams from 126 qualified subjects (756 teeth) were included. Implants were virtually positioned in two different positions: in the long axis of the tooth (prosthetically-driven position) and in an ideal position in relation to adjacent anatomical structures (bone-driven position). Two different implant diameters were planned for each tooth position, namely, 3.75 and 4.3 mm for central incisors and canines, and 3.0 and 3.3 mm for lateral incisors. The incidence of perforation was nearly 80% and 5% for prosthetically- and bone-driven position, respectively. Factors associated with a higher risk of cortical bone wall perforation (bone-driven position), according to logistic regression analysis, were women, wider implants, Sagittal Root Position class IV, and decrease of the labial concavity angle. Perforation of the labial cortical bone wall can be greatly minimized when the implant is placed in a bone-driven position compared to a prosthetically-driven position. It is important to preoperatively evaluate the morphological features of the implant site for risk assessment and to individualize the treatment plan.

Antimicrobial photodynamic therapy and guided endodontics: A case report.

A 35-year-old woman with a history of pulp canal obliteration (PCO) and apical periodontitis was treated with guided endodontics combined with antimicrobial photodynamic therapy (aPDT). The use of aPDT was paramount to the approach performed, and its application should be encouraged in cases of severely calcified canals when apical patency is unachievable. The combination of these techniques ensured successful clinical, radiographic, and tomographic outcomes at the 1-year follow-up. Key Words: Antimicrobial PDT, guided endodonics, periodontitis, pulp canal obliteration.

Guided Endodontics in Complex Scenarios of Calcified Molars.

This study aimed to report a case series and describe the use of guided endodontics in complex symptomatic cases of mandibular and maxillary molars; presenting calcification of all three root canals. The arches of the referred patients were scanned, and high-resolution cone-beam computed tomography (CBCT) imaging was performed. Then, the taken CBCT and tooth scans were aligned and processed using software. A virtual copy of a drill was superimposed onto the scans and evaluated in 3 dimensions. Subsequently, a 3-dimensional (3D) template was designed and printed. Drilling was performed and a radiograph was taken to confirm its position. The canals were reached and endodontic treatment was performed. At the 12-month follow-up, the teeth were completely asymptomatic. The use of guided endodontics in cases of calcification in molars was demonstrated to be a viable and reliable alternative treatment. The technique was based on 3D planning.

Guided Endodontics in Nonsurgical Retreatment of a Mandibular First Molar: A New Approach and Case Report.

This case report describes the use of the guided endodontics for a non-surgical endodontic retreatment of the mandibular molar. A 38-year-old female reported apical swelling and localized pain on the tooth #30, exacerbated when chewing hard food. Periapical radiographic examination showed pulp canal obliteration in the apical third associated with extensive radiolucent area. Cone-beam computed tomography (CBCT) images were requested to support the diagnosis and enable preparation of a surgical guide, used to direct access to the canals that were obliterated and incompletely filled. The follow-up at 24 months radiographically showed completely healed apical area in the involved tooth. This non-surgical technique demonstrated efficacy in case resolution.

3D Apicoectomy Guidance: Optimizing Access for Apicoectomies.

When conventional endodontic treatment resources are depleted, endodontic surgery becomes an alternative treatment for apical periodontitis to remove unreachable infected areas and seal the root canal. Digital workflows have been used more frequently in many dental applications in recent years. In endodontics, virtual 3-dimensional (3D) planning and endodontic guidance are new aspects important for the treatment of complex cases. This report aimed to present 3D Apicoectomy Guidance, a novel method of performing guided ultraconservative endodontic surgery with conventional implant-guided drills, and to describe its application in a case with a complex anatomic scenario and intimate contact with the maxillary sinus. Implantology computer software, as well as cone-beam computed tomography images and a digital scanning 3D impression, enabled virtual planning of the surgical procedure. Subsequently, a 3D template was produced to guide the instruments used in the osteotomy and root resection. The patient was completely asymptomatic at the 1-week follow-up visit. Cone-beam computed tomography scans were performed at 1 and 6 months after surgery and showed that resection of the apex of the root was performed accurately and that a thin dentin slice remained distally, preventing the rupture of the sinus membrane. The patient remained asymptomatic, and the tissue healed normally. The method used was shown to be very straightforward and reliable. This method allowed the patient to be treated expeditiously with very precise tissue removal.

Case Reports in Maxillary Posterior Teeth by Guided Endodontic Access.

The localization of partial or completed root canal obliteration is a challenging task in endodontic practice. Recently, guided endodontics has become an alternative solution for those cases. Although this technique has already been used clinically in managing anterior teeth, in this report, we describe 3 complex clinical scenarios of calcified root canals of 1 molar and 2 premolars using guided endodontics. The clinical cases reported here show that technological evolutions should make guided endodontic procedures more widespread because their execution is relatively fast and safe even in the case of the upper molar. Additionally, 12-month clinical follow-up visits showed the effectiveness of the guided endodontic procedures.

Three-dimensional endodontic guide for adhesive fiber post removal: A dental technique.

This dental technique describes a protocol for adhesive fiber post removal using a prototyped endodontic guide. The removal of an adhesive fiber post is an important step for endodontic retreatment and the resolution of prosthetic problems. Computer-aided design and computer-aided manufacturing (CAD-CAM) technology was used to generate guides with prototyping and is a useful tool for fiber post removal.

Guided Endodontic Access of Calcified Anterior Teeth.

Pulp canal calcification is characterized by the deposition of calcified tissue along the canal walls. As a result, the root canal space can become partially or completely obliterated. Recently, "guided endodontics" has been reported as an alternative solution in cases of partial or completed canal obliteration. Although this technique can enhance minimally invasive access to the calcified canal, it has been shown that the incisal surfaces are often removed during the access of anterior teeth. This report describes 2 cases of guided endodontics using conventional palatal access in calcified anterior teeth and discusses the applicability of this approach in cases of pulp canal calcification with apical periodontitis and acute symptoms. The method demonstrated high reliability and permitted proper root canal disinfection expeditiously, without the unnecessary removal of enamel and dentin in the incisal surface.

Immediate implant placement in the posterior mandible: A cone beam computed tomography study.

OBJECTIVE: To determine the longest upright and tilted implant that can be placed in posterior mandibular teeth (second premolars [2PM], first molars [1M], and second molars [2M]) in case of immediate implant placement (IIP), respecting a safe distance from the inferior alveolar canal (IAC) and the submandibular fossa, using cone beam computed tomography (CBCT) scans. METHOD AND MATERIALS: In CBCT scans of 118 subjects, the following were measured: distance from the tooth apex to the IAC (DTC), lateromedial width of the mandible, classification of mandibular cross-sectional morphology, upright and tilted implant placement simulation, tilting angle that allowed placement of the longest implant. RESULTS: The DTC has shown to be greater for 1M, shorter for 2PM, and even shorter for 2M. Between 70% and 88% of all 2PM, 1M, and 2M present less than 6 mm of DTC. The cross-sectional morphology of the mandible had a tendency to be classified as "undercut" in more posterior regions. For both 4.0- and 5.0-mm implants, more posterior regions resulted in a greater difference in length between the upright and tilted implants. The tilting angle was greater for the more posterior regions. Most of the relationships between age/sex and the morphometric parameters were weak. CONCLUSION: Lingual concavity is a common clinical finding at the posterior mandibular region, and its occurrence varies according to the tooth type. The great majority of the 2PM, 1M, and 2M present limited available bone between the root apex and the IAC, which stresses the need for careful attention when IIP is planned in this area.

Comparison of 64-Detector-Multislice and Cone Beam Computed Tomographies in the Evaluation of Linear Measurements in the Alveolar Ridge.

This study compared the accuracy of linear measurements of the alveolar ridge in images obtained using 64-detector-multislice computed tomography (CT) and cone beam CT (CBCT). Eight sites were selected corresponding to the regions of molars, premolars, canines, and incisors in six dry human jaws. After the completion of multislice CT and CBCT, the jaws were sectioned into specific regions. Results showed there was no statistically significant difference between the measurements obtained from the CT images and those obtained from dry jaws (actual measurements) for all the evaluated sites (molars, premolars, and anterior teeth). There was also no statistically significant difference between the measurements obtained by the two CT methods.

A morphometric analysis of the mandibular canal by cone beam computed tomography and its relevance to the sagittal split ramus osteotomy.

PURPOSE: The aim of the present study was to morphometrically analyze the mandibular canal through the mandibular ramus by cone beam computed tomography (CBCT) and to relate the findings to performing sagittal split ramus osteotomy. METHODS: CBCT of 200 patients were analyzed. Five parameters were measured at the axial scan, from the mandibular foramen to 21 mm below it (3-mm intervals). The canal was classified according to the position within the bone marrow space. Variations were evaluated according to age, sex, side, and number of mandibular teeth. RESULTS/CONCLUSIONS: The following measurements increased gradually towards the most inferior level of measurement: the total thickness of the mandibular ramus through the center of the mandibular canal, the width of the bone marrow space (both buccal and lingual), and the narrowest width from the mandibular canal inner cortical to the mandibular ramus external cortical. The inner diameter of the mandibular canal slightly decreased to the same direction. Concerning the mandibular canal position within the bone marrow space, the percentage of the separate type increased towards the most inferior level of measurement, and the contact and fusion types decreased. Age, number of teeth, and sex had no significant influence on the total thickness of the mandibular ramus and on the narrowest width from the mandibular canal inner cortical to the mandibular ramus external cortical.

Anatomic variations and lesions of the mandibular canal detected by cone beam computed tomography.

PURPOSE: The mandibular canal is a significant anatomical structure in implant dentistry, and cone beam computed tomography (CBCT) is an important diagnostic image modality in this field of dentistry. The aim of this study was to evaluate the frequencies of anatomic variations and lesions affecting the mandibular canal in CBCT images of the mandible produced for dental implant planning. METHODS: This cross-sectional study evaluated a sample of 250 CBCT examinations (500 mandibular canals). The inclusion criterion was CBCT examinations of the mandible requested for dental implant planning. The presence of anatomic variations and lesions affecting the mandibular canal was evaluated in the CBCT examinations. Moreover, the buccolingual position of the mandibular canal was evaluated in the molar region and in the ramus region. The CBCT exams were evaluated by one observer. The data were analyzed using descriptive and analytical statistics. The one-way ANOVA test was employed to compare the age between the anatomic variations. A paired t test was used to compare the buccolingual position between the molar region and the ramus region. Differences were considered significant when p values were lower than 0.05. RESULTS: The anatomic variations detected were large-diameter mandibular incisive canal (51.6 %), ramification (12 %), and accessory mental foramen (3.2 %). No difference was observed in the age of the patients between the anatomic variations (p > 0.05). The identified lesions included hypomineralization of the canal walls (20.8 %), idiopathic osteosclerosis (8.8 %), osteolytic lesions (3.2 %), iatrogenic perforation of the mandibular canal (2.8 %), and fibro-osseous lesions (1.6 %). The distance between the mandibular canal and the vestibular cortical bone was higher in the molar region than in the ramus region (p < 0.05). CONCLUSIONS: Anatomic variations and lesions affecting the mandibular canal were common findings in the CBCT images of the mandible produced for dental implant planning. An awareness of these alterations is important for dentistry because some of them might require treatment, change oral surgery planning and difficult inferior alveolar nerve anesthetic block.

Expression of metallothionein and p53 antigens are correlated in oral squamous cell carcinoma.

BACKGROUND: Metallothionein and p53 proteins have been associated with tumoral evolution and resistance against therapy. Experimentally, the former may modulate the activity of tumor suppressor protein through zinc exchange. However, there is no information on the relationship of these proteins in oral cancer. PATIENTS AND METHODS: Immunohistochemical detection of metallothionein and p53 antigens was performed in 100 oral squamous cell carcinomas. Results were compared to evaluate possible relationships between them and the disease-specific survival. RESULTS: Mean cellular indexes of positivity were 66.5% and 52.5% for metallothionein and p53, respectively, and a positive correlation was found between them. Frequent nuclear metallothionein immunolocalization was associated to increased p53 expression. Concomitant overexpression of both antigens predicted shorter survival for patients with advanced disease. CONCLUSION: These results corroborate the speculated association between metallothionein and p53 and suggest that simultaneous assessment of these proteins may be useful to evaluate aggressiveness of oral cancer.