Benito Rilo

Comparison of the fracture resistances of pulpless teeth restored with a cast post and core or carbon-fiber post with a composite core

STATEMENT OF PROBLEM The survival of pulpless teeth restored with a post and core system is a controversial issue. PURPOSE This study compared the fracture resistance of 2 types of restorations: teeth restored with prefabricated carbon-fiber posts and composite cores to cast dowel-core restored teeth. MATERIAL AND METHODS A total of 44 recently extracted sound premolars were randomly distributed into 2 equal groups: group I, restored with prefabricated carbon-fiber post and a composite core; and group II, with custom-cast type III gold alloy post and cores. The size and shape of the posts were identical in the 2 groups. All teeth were fully covered with a nonprecious cast crown. Fracture resistance was measured by applying a point force at 45 degrees to the long angle of the tooth. RESULTS Mean fracture threshold was 103.7 +/- 53.1 kg for group I versus 202.7 +/- 125.0 kg for group II (differences significant with P = .003). In group II, however, fracture nearly always affected the tooth itself, whereas in group I, the post-core nearly always failed first. CONCLUSIONS Significantly higher fracture thresholds were recorded for the cast post and core group. Teeth restored with cast posts typically showed fracture of the tooth, although at loads rarely occurring clinically.

Distance of the contact glide in the closing masticatory stroke during mastication of three types of food

This study was designed to characterize the distance of the contact glide in the closing masticatory stroke in healthy adult subjects, during chewing of three types of food (crustless bread, chewing gum and peanuts). Mandibular movements (masticatory movements and laterality movements with dental contact) were registered using a gnathograph (MK-6I Diagnostic System) on the right and left side during unilateral chewing of the three food types. Length of dental contact was measured in masticatory cycle, which is defined as where the terminal part of the chewing cycles could be superimposed on the pathways taken by the mandible during lateral excursions with occlusal contacts. The length of dental contact during mastication of chewing gum is 1.46 +/- 1 mm, during chewing of soft bread is 1.38 +/- 0.7 mm and during chewing of peanuts is 1.45 +/- 0.9 mm. There is no significant difference in the lengths of dental contact during mastication of three types of foods that enable direct tooth gliding.

Myoelectric activity during unilateral chewing in healthy subjects: Cycle duration and order of muscle activation

STATEMENT OF PROBLEM Craniomandibular disorders, unilateral mastication, and asymmetry of masticatory muscles appear to be related to each other. Thus, it is of interest to investigate masticatory muscle activity during unilateral mastication in healthy subjects. PURPOSE This study monitored contractile activity of the right and left masticatory muscles during right- and left-side gum chewing. MATERIAL AND METHODS Electromyographic techniques were used to determine chewing cycle duration and duration of contractile activity of the masticatory muscles (right and left masseter and anterior temporalis muscles) during unilateral chewing in 40 subjects without orofacial pain. The time-course of activation of the 4 muscles was also investigated. RESULTS Electromyographic traces showed extensive interindividual variation. In both right- and left-side chewing tests, and regardless of whether the masseter or the temporalis muscles were considered, mean duration of the contraction phase did not differ significantly between the working and nonworking sides. The working side temporalis contracted first, whether alone or at the same time as the other muscles. CONCLUSIONS In healthy subjects, no significant differences in masticatory muscle activity should be expected between either the right and left or the working and nonworking sides.

Midline shift and lateral guidance angle in adults with unilateral posterior crossbite

INTRODUCTION Unilateral posterior crossbite is a malocclusion that, if not corrected during infancy, typically causes permanent asymmetry. Our aims in this study were to evaluate various occlusal parameters in a group of adults with uncorrected unilateral posterior crossbite and to compare findings with those obtained in a group of normal subjects. METHODS Midline shift at maximum intercuspation, midline shift at maximum aperture, and lateral guidance angle in the frontal plane were assessed in 25 adults (ages, 17-26 years; mean, 19.6 years) with crossbites. RESULTS Midline shift at maximum intercuspation was zero (ie, centric midline) in 36% of the crossbite subjects; the remaining subjects had a shift toward the crossbite side. Midline shift at maximum aperture had no association with crossbite side. Lateral guidance angle was lower on the crossbite side than on the noncrossbite side. No parameter studied showed significant differences with respect to the normal subjects. CONCLUSIONS Adults with unilateral posterior crossbite have adaptations that compensate for the crossbite and maintain normal function.

A Simplified Palatal Lift Prosthesis for Neurogenic Velopharyngeal Incompetence

Velopharyngeal incompetence is a contributing factor to speech disorders and implies the presence of hypernasality, inappropriate nasal escape, and decreased air pressure during speech. One prosthetic treatment is a rehabilitative procedure employing a palatal lift prosthesis (PLP), which reduces hypernasality by approximating the incompetent soft palate to the posterior pharyngeal wall and consists of two parts, the anterior denture base and the palatal lifting plate, which are connected with steel wires; however, it seems difficult to reproduce the mobility of the soft palate in speaking, and it is therefore likely that the palatal lifting plate stimulates or oppresses the tissue of the soft palate and hinders rather than assists articulatory function. To avoid these disturbances we devised an adjustable PLP with a flexible conjunction between the denture base and the palatal lifting plate to obtain the optimal vertical lifting angle. The palatal plate was adapted to conform in a passive manner to the soft palate with light-cured resin. The designed PLP simplified the procedure and reduced the number of adjustments and visits.

A Prosthetic Alternative for Severely Angled Implants Beneath a Maxillary Overdenture: A Clinical Report

Implant-retained overdentures have been shown to be a predictable, accepted option and represent a viable and cost-effective treatment; however, patients with severe lack of bone volume and anatomical limitations are often a contraindication to the placement of osseointegrated implants without prior surgical procedures. In these situations, the placement of angled implants may offer a simple solution. This clinical report describes a case of dental rehabilitation using angled implants for a patient with a severely resorbed edentulous maxilla. The inclination has been solved by making a bar on the right side and individual pillars on the left side so as to obtain a functional and esthetic prosthetic result.

Radiographic Assessment Of Crestal Bone Loss In Tissue-Level Implants Restored By Platform Matching Compared With Bone-Level Implants Restored By Platform Switching: A Randomized, Controlled, Split-Mouth Trial With 3-Year Follow-Up

PURPOSE This randomized, controlled, split-mouth trial with 3-year follow-up was carried out to compare radiologic changes of crestal bone level (CBL) between splinted tissue-level implants restored by platform matching and bone-level implants restored by platform switching. MATERIALS AND METHODS Periapical radiographs were taken to evaluate the peri-implant crestal bone changes at baseline (implant restoration), at 1 year, and at 3 years after the definitive restoration. RESULTS Thirty-five patients requiring a partial fixed dental prosthesis supported by two implants had their sites randomized according to receiving both implant types. Fifty tissue-level implants restored by platform matching, as control implants, and 50 bone-level implants restored by platform switching, as test implants, were placed. Crestal bone changes in the control group were: baseline to 3 years, 0.18 ± 0.46 mm (P = .043). In the test group, crestal bone changes were: baseline to 3 years, 0.14 ± 0.35 mm (P = .514). The mean differences between groups were: baseline to 1 year, 0.07 ± 0.23 mm (95% CI: -0.034, 0.185); 1 to 3 years, 0.01 ± 0.01 mm (95% CI: -0.055, 0.074); baseline to 3 years, 0.04 ± 0.11 mm (95% CI: -0.080, 0.150). No statistically significant differences in CBL at baseline to 1 year (P = .269), 1 year to 3 years (P = .811), and baseline to 3 years (P = .513) were observed. CONCLUSION In this trial, CBL changes in the tissue level control group were statistically significant only between baseline and 3-year follow-up. Meanwhile, CBL changes in the bone-level test group were not statistically significant in the different times studied. No statistically significant difference in CBL between two implant types was observed.

Crestal Bone Level Around Tissue-Level Implants Restored with Platform Matching and Bone-Level Implants Restored with Platform Switching: A 5-Year Randomized Controlled Trial

PURPOSE The aim of this randomized clinical trial with a 5-year follow-up was to assess the differences in radiographic levels of peri-implant bone crest between tissue-level implants restored with platform matching (control group) and bone-level implants restored with platform switching (test group) in the posterior region. MATERIALS AND METHODS To assess marginal bone level changes, periapical radiographs were taken at the moment of prosthesis delivery (baseline), at 1 year, and at 5 years after the definitive restoration. RESULTS One hundred subjects, partially edentulous in the posterior region, were selected for this study. There were 54 men and 46 women between the ages of 25 and 70 years (mean = 50.5 years). A total of 202 implants were assigned to both groups using a randomized procedure (100 implants in the control group and 102 in the test group). The mean marginal bone level (MBL) changes for tissue-level implants restored with platform matching were 0.26 ± 0.55 mm at baseline to 1 year, 0.34 ± 0.54 mm at 1 year to 5 years, and 0.61 ± 0.73 mm at baseline to 5 years. The mean MBL changes for bone-level implants restored with platform switching were -0.03 ± 0.74 mm at baseline to 1 year, -0.17 ± 0.67 mm at 1 year to 5 years, and -0.20 ± 0.75 mm at baseline to 5 years. The mean difference between the two groups was 0.31 mm at baseline to 1 year, 0.53 mm at 1 year to 5 years, and 0.85 mm at baseline to 5 years. There was a statistically significant difference in MBL (P < .001). Both implant systems showed good and similar survival rates (98% for tissue-level implants restored with platform matching and 96.1% for bone-level implants restored with platform switching). CONCLUSION In this randomized controlled trial, the following observations were made. Radiographic levels of peri-implant bone crest in tissue-level implants restored by platform matching were statistically significant in the three interval times. Meanwhile, MBL changes for bone-level implants restored with platform switching were not statistically significant in the different times studied. Nevertheless, the mean difference between the two groups was statistically significant.

Implant Rehabilitation Planning Protocol for the Edentulous Patient According to Denture Space, Lip Support, and Smile Line

Rehabilitation with implants is a challenge. Having previous evaluation criteria is key to establishing the best treatment for the patient. In addition to clinical and radiological aspects, the prosthetic parameters must be taken into account in the initial workup, since they allow discrimination between fixed and removable rehabilitation. We present a study protocol that analyzes three basic prosthetic aspects. First, denture space defines the need to replace teeth, tissue, or both. Second, lip support focuses on whether or not to include a flange. Third, the smile line warns of potential risks in esthetic rehabilitation. Combining these parameters allows us to make a decision as to the most suitable type of prosthesis. The proposed protocol is useful for assessing the prosthetic parameters that influence decision making as to the best-suited type of restoration. From this point of view, we think it is appropriate for the initial approach to the patient. In any case, other considerations of study may amend the proposal.

Implant Impression for Full-Banded Orthodontic Patient

I mplant dentistry now forms an integral part of routine dental practice, and implants are used in multidisciplinary treatment. Dental implants are becoming popular in orthodontic treatment. They can be used to reposition natural teeth and to increase treatment options. Treatment that combines orthodontics and implantology is now extensively used in dentistry. In certain cases, implants replace teeth prior to termination of orthodontic treatment. However, accurate impressions are difficult to obtain at this time because the bands and wires trap the impression material. Also, orthodontic devices can tear the impression material. Few techniques for implant impression in orthodontic patients have been reported. Lorton described a method to facilitate impressions of orthodontically banded teeth using strips of occlusal indicator wax. Drago obtained intact, accurate irreversible hydrocolloid impressions to make a maxillary splint. Sukotjo proposed the fabrication of a simple implant surgical template to be used in implant therapy involving orthodontics devices. Maeda et al referred to a method of mouthguard fabrication for orthodontic patients that allows reproduction of the occlusal and incisal surfaces using irreversible hydrocolloid. However, with these methods, a precise casting of the implant is not possible. Obtaining a precise impression with stable dimensions of implant is necessary for passive fit, and it demands precise transfer of the spatial relationships of the implant from the mouth to the master cast to ensure passive fit of implant framework. Irreversible hydrocolloid is useful in preliminary impressions, diagnostic casts, mouthguards, bleaching trays, and orthodontics casts. In implant impressions, however, it has the disadvantages of low dimensional stability and reduced capacity for detail reproduction. On the other hand, the usual impression materials for implants are too rigid to allow removal from the mouth. This article proposes a simple impression implant technique for an orthodontic patient without bracket remotion. Combining 2 types of impression materials makes it possible to obtain an exact reproduction of the implant position, yet the material can be easily removed. TECHNIQUE