Won Suk Oh

Mandibular Fracture in Conjunction with Bicortical Penetration, Using Wide-Diameter Endosseous Dental Implants

Prosthodontic rehabilitation of a patient with an atrophic edentulous mandible presents a significant challenge in restoring esthetics and function. The purpose of this clinical report is to describe fracture of an atrophic edentulous mandible opposing maxillary natural dentition in association with endosseous dental implants. The patient received two wide-diameter implants in the anterior mandible for an implant-assisted mandibular overdenture, in which the implants penetrated the inferior border of the mandible for bicortical stabilization. Three months following implant placement surgery, the patient experienced pain, swelling, and intraoral purulent drainage around the right implant. Panoramic radiograph revealed a fracture of the mandible through the right implant site and signs of infection around the left implant. The implants were removed surgically, and open reduction and fixation of the fracture site were undertaken using a titanium bone fixation plate. This clinical report demonstrates that placement of wide-diameter implants in conjunction with bicortical penetration in a severely atrophic edentulous mandible can risk fracture of the mandible.

A simple method to duplicate a denture for an implant surgical guide

aClinical Associate Professor, Department of Biologic and Materials Sciences, Division of Prosthodontics. bClinical Assistant Professor, Department of Biologic and Materials Sciences, Division of Prosthodontics. (J Prosthet Dent 2008;99:326-327) A duplicate of an existing prosthesis is often used as a surgical guide to assist in surgical placement of a dental implant. Various duplication methods have been described in the literature.1-5 Generally, the existing denture is evaluated and determined to be adequate for esthetics and function, embedded in an impression material, retrieved, and the space inside the mold is filled with an acrylic resin. These methods, however, require special instruments or materials for the duplication procedure that may not be readily available. Irreversible hydrocolloid material is a widely used impression material because it is accurate, easy to use, and relatively inexpensive.6 This article describes a procedure for duplicating an existing interim removable partial denture (IRPD) using irreversible hydrocolloid impression material and a plastic container. This procedure is simple and employs materials that are commonly used and readily available in a dental laboratory.

Comparison of Clinical and Radiographic Outcomes of Platform-Switched Implants with a Rough Collar and Platform-Matched Implants with a Smooth Collar: A 1-Year Randomized Clinical Trial

PURPOSE The aim of this study was to evaluate and compare the clinical and radiographic outcomes of single implants with a platform-switched rough collar (PSRC) and a platform-matched smooth collar (PMSC). MATERIALS AND METHODS Twenty-six patients missing a tooth in the anterior maxilla (through the premolars) were randomly assigned to the PSRC or the PMSC group. All implants were placed in a flapless approach and restored with an early loading protocol. Clinical measurements were performed at surgery, loading, and at 3, 6, and 12 months after loading. In addition, radiographic evaluations were carried out using standardized periapical radiographs and cone beam computed tomography. Patient satisfaction surveys were completed, and microbial analysis with DNA probes was performed. RESULTS The implant survival rate was 100% for both groups. The mean marginal bone level (MBL) was significantly higher in the PSRC group compared to the PMSC group at all time points. From the 2-week postoperative visit to 1 year postloading, the mean MBL change in the PSRC group was 0.21 ± 0.56 mm and in the PMSC group it was 0.74 ± 0.47 mm. Soft tissue profiles were stable over time, with no significant differences between groups. There were no significant differences between groups in the number of microbial species seen. Patients in both groups were highly satisfied with postoperative and postprosthetic experiences. CONCLUSION In this study, the PSRC method preserved marginal bone by a mean of 0.53 mm more than the standard PMSC protocol. Within the limitations of the present study, it can be concluded that the PSRC protocol may be beneficial in marginal bone preservation. Longitudinal studies are needed to verify the long-term effects of this approach.

Use of a thermoplastic vacuum-formed matrix for secure engagement of an implant surgical template

Oh and Saglik Oh and Saglik Endosseous dental implants should be placed to permit the ideal contour and thickness of the definitive prosthesis.1,2 A diagnostic waxing is developed to plan the optimal position and inclination of the implants to maximize esthetics, facilitate framework design, minimize the cantilever effect, and enhance hygiene access.1-4 The surgical template is fabricated to duplicate the waxing and incorporate plastic or metal tubes to accommodate drills of different sizes for precise implant placement.3,4 However, the surgeon may elect not to use the surgical template if its intraoral placement is not adequately stable or rigid, or if it limits accessibility to the surgical field.5 An interim removable partial denture (IRPD) is a provisional prosthesis fabricated to accommodate the patient’s need and desire for esthetics and function until definitive treatment is rendered.6 The prosthesis may be duplicated in clear acrylic resin and modified to serve as a guide for implant placement.7-9 However, intraorally, the guide may not be secure and stable due to the lack of support provided by the soft tissue of the residual ridge. Reflection of the mucoperiosteum for implant placement further interferes with adequate seating of the guide and restricts accessibility to the surgical field. Engagement of the remaining dentition would assist an accurate orientation and maintain the duplicate IRPD (DRPD) to serve as a surgical template. This paper deUse of a thermoplastic vacuum-formed matrix for secure engagement of an implant surgical template

Impact of implant support on mandibular free-end base removable partial denture: theoretical study

OBJECTIVES This study investigated the impact of implant support on the development of shear force and bending moment in mandibular free-end base removable partial dentures (RPDs). MATERIAL AND METHODS Three theoretical test models of unilateral mandibular free-end base RPDs were constructed to represent the base of tooth replacement, as follows: Model 1: first and second molars (M1 and M2); Model 2: second premolar (P2), M1, and M2; and Model 3: first premolar (P1), P2, M1, and M2. The implant support located either at M1 or M2 sites. The occlusal loading was concentrated at each replacement tooth to calculate the stress resultants developed in the RPD models using the free-body diagrams of shear force and bending moment. RESULTS There was a trend of reduction in the peak shear force and bending moment when the base was supported by implant. However, the degree of reduction varied with the location of implant support. The moment reduced by 76% in Model 1, 58% in Model 2, and 42% in Model 3, when the implant location shifted from M1 to M2 sites. CONCLUSIONS The shear forces and bending moments subjected to mandibular free-end base RPDs were found to decrease with the addition of implant support. However, the impact of implant support varied with the location of implant in this theoretical study.

Prosthodontic treatment considerations for patients with oral sinonasal mucosal malignant melanoma: A clinical report

Patients with a diagnosis of mucosal malignant melanoma involving the maxilla or paranasal sinuses requiring surgery are referred to the maxillofacial prosthodontist for treatment. The standard protocol of surgical, interim, and definitive obturator treatment is usually anticipated. Depending upon the stage and presence or absence of metastasis, it is generally accepted that the prognosis for cure of this disease is poor. This clinical report reviews the current literature regarding treatment and the overall guarded prognosis for this disease, and reports the prosthodontic treatment intervention for 8 patients. Prosthodontic treatment strategies are recommended that are consistent with the reality of the diagnosis to achieve optimal function and quality of life for these patients.

Incisive Papilla Line as a Guide to Predict Maxillary Anterior Tooth Display

Oh and Hansen Oh and Hansen Maxillary anterior tooth display should be predicted and controlled for an esthetic outcome in an edentulous patient.1 The customary prosthodontic procedure requires an occlusion wax rim to be contoured for adequate lip support and occlusal vertical dimension determination.2 The lip line is marked on the rim when the patient is in the full smile to determine the amount of tooth display and guide the selection of the artificial denture teeth. However, the smile line is dynamic, and the degree of anterior tooth display will vary depending on gender, race, lip fullness, age, and upper lip length.3,4 The upper lip length is measured from the base of the columela to the tip of the philtrum to aid in the selection and positioning of the anterior teeth.3 In general, the longer the upper lip, the less the maxillary teeth are visible, and vice versa. However, the lip length as measured according to the facial morphology may not always provide an accurate estimation of the relative amount of tooth display, both at rest and in the full smile, because of a large variability in maxillary lip line relative to the incisal edge position.3,4 The incisive papilla remains relatively constant in both vertical and horizontal locations, except when combined with excessive resorption of alveolar bone, and is frequently used as an anatomic landmark in arranging maxillary anterior teeth.2,5-7 The mean vertical distance between the incisive papilla and the incisal edges of maxIncisive papilla line as a guide to predict maxillary anterior tooth display

Tooth reduction guide using silicone registration material along with vacuum-formed thermoplastic matrix

Adequate tooth reduction is a prerequisite for function, esthetics, and longevity of fixed restorations. A tooth reduction guide may be useful for establishing the proper angulation of the tooth and maximizing periodontal health and restorative success. This article describes a simple and versatile technique for an accurate evaluation of tooth reduction for fixed restorations by using a color-contrasting positive guide of a silicone occlusal registration material processed inside a vacuum-formed clear thermoplastic matrix.

The commissure line of the mouth for orienting the occlusal plane.

This study investigated the positional relation of the commissure line of the mouth to the maxillary first molars. Thirty-five volunteers, 20 to 40 years old, with normal natural dentitions were recruited. Maxillary casts with marks locating the commissure were digitally scanned to measure the vertical distance from the tip to the base of the mesiofacial cusp (CO) and from the tip to the mark (CM). There was no significant difference (t test; P > .05) between the CO (1.61 ± 0.41 mm) and CM (1.14 ± 0.68 mm). The mean distance of the commissure mark from the occlusal plane was 0.78 mm.

One-step mounting of diagnostic casts demonstrating loss of posterior occlusal support

aClinical Associate Professor, Department of Biologic and Materials Sciences Division of Prosthodontics. bDental student. (J Prosthet Dent 2012;107:276-277) Proper mounting of diagnostic casts is an important step in formulating a treatment plan for a partially edentulous patient where registration of the maxillomandibular relationship is a prerequisite.1-3 This procedure can provide stable occlusal support in a single clinical appointment when a patient presents with teeth in all 4 posterior sextants. However, mounting of casts can be complicated by loss of posterior occlusal support.4-6 A laboratory procedure is generally needed to fabricate a record base and occlusion rim before making a registration of the maxillomandibular relationship. The record base is placed intraorally to provide a support for the recording medium. This method of cast mounting generally requires an additional appointment because of the laboratory procedures involved. Thus, cast orientation is often performed inaccurately by means of a simple silicone occlusion registration record processed intraorally against the teeth and edentulous mucosa of the ridge but without support from a record base. This procedure is unacceptable because of the misfit of the silicone record against the edentulous areas of the stone cast, which is generated from an irreversible hydrocolloid impression material. This article describes an alternative diagnostic mounting procedure for a partially edentulous patient presenting with loss of posterior occlusal support, where silicone occlusion registration material is extruded intraorally and polymerized before making a preliminary impression. This silicone record is incorporated into the impression to present the surface morphology of the edentulous ridge. This method expedites the diagnostic cast mounting procedure by eliminating the need for a record base and is particularly useful when the interarch distance is restricted, preventing placement of a record base and occlusion rim (Fig. 1). However, care should be taken to avoid overclosure of the casts because of the resiliency of the silicone record.7