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PubMedDate not supplied

Long-term marginal periimplant bone loss in edentulous patients.

PURPOSE: The aim of this study was to examine the long-term periimplant bone loss in patients treated with implant-supported fixed prostheses in both jaws. MATERIALS AND METHODS: The participants comprised 44 edentulous patients who have been followed for a 15-year period after treatment with a fixed implant-supported prosthesis in the mandible. Thirteen of them also received an implant-supported fixed prosthesis in the maxilla, on average 4.5 years after the mandibular treatment. The periimplant bone level was measured on intraoral radiographs. RESULTS: The long-term results of the implant treatment were successful, and only 1% (3/273) of the implants were lost in the mandible and 7% (5/75) in the maxilla. All but one of the failures occurred before the connection of the prostheses. The mean marginal bone loss around the implants was small (less than 1 mm for a 10-year period after implant placement), and was of similar magnitude in both jaws. However, the individual variation was relatively great. There was no significant difference in marginal bone loss between those who had a maxillary complete denture during the entire observation period and those who had received a fixed implant-supported maxillary prosthesis. Smokers lost more periimplant bone than did the nonsmokers; the difference was significant in the mandible but small and nonsignificant in the maxilla. CONCLUSION: The long-term periimplant bone loss was small and of similar magnitude in the mandible and the maxilla in subjects who had received implant-supported fixed prostheses in both jaws. The prosthetic status in the maxilla, i.e., complete denture or fixed implant-supported prosthesis, had no significant influence on the mandibular periimplant bone loss.

Adult↗
PubMed1998

Loading of a unilateral temporomandibular joint prosthesis: a three-dimensional mathematical study.

The load on the prosthetic side and the influence of the design on the remaining natural contralateral TMJ must be known before a unilateral temporomandibular joint (TMJ) prosthesis can be developed. The aim of the present study was to determine the maximum loading of the TMJ prosthetic side and the natural contralateral TMJ and to investigate the influence of the location of the center of rotation of the prosthesis on the maximum loading. For this purpose, a mathematical model of the mandible with a unilateral TMJ prosthesis with a fixed center of rotation (CR) was developed. The location of the CR of the TMJ prosthesis was varied from the middle of the natural mandibular condyle to 15 mm inferior to this location. Although the maximum joint reaction forces changed as a result of a unilateral TMJ prosthesis, the trend of the loading curves was similar to that of an intact mandible. A unilateral TMJ prosthesis resulted in a 50% higher loading of the prosthetic side, while the load on the natural contralateral TMJ remained within normal limits. The maximum load on the prosthetic side occurred during molar bites and could reach 100 N in the cranial direction, 30 N in the ventral direction, and 25 N in the medio-lateral direction. The location of the CR did not have a significant influence on the loading of the TMJ prosthesis and the natural contralateral TMJ.

Adult↗
PubMed1999

The theoretical optimal center of rotation for a temporomandibular joint prosthesis: a three-dimensional kinematic study.

A unilateral temporomandibular joint (TMJ) prosthesis may cause dysfunction of the contralateral, natural TMJ because of lack of translatorial movements of the prosthetic side. The natural translatorial capacity of the mandible can be restored in part by a TMJ prosthesis with a fixed center of rotation (CR), positioned inferiorly to the center of the natural mandibular condyle. The aim of this study was to determine the optimal position for the fixed CR of a unilateral TMJ prosthesis. A mathematical model was used to analyze different positions of the CR. These positions were evaluated based on the calculated rotation of the mandible in the frontal (theta f) and horizontal (theta h) plane, and the mediolateral movement (MLM) of the contralateral natural condyle. For current TMJ prostheses, with the CR positioned in the center of the natural condyle, theta h exceeded the natural limits. When the CR was shifted inferiorly, all parameters improved, particularly theta h. The addition of an anterior shift to an inferior shift slightly worsened theta f, while the addition of a posterior shift to an inferior shift slightly improved theta f and worsened MLM. We concluded that the functioning of the contralateral TMJ improves by shifting the CR inferiorly. An anterior shift may be added to remain within the contour of the mandibular ramus. The proposed position of the CR is 15 mm inferior to the center of the natural condyle, combined, if necessary, with an additional anterior shift of 5 mm.

Humans↗
PubMed1988

Reconstruction of mandibular defects with metallic prostheses and microvascular jejunal autografts: an experimental study.

A study was undertaken to determine the adequacy of vascularised jejunum to provide stable mucosal cover over a non-biological mandibular substitute. Employing a canine model, composite intra-oral bone-mucosal defects were created and reconstructed with a metal plate covered by a microvascular jejunal patch. These were followed for six months and were assessed clinically, histologically and radiologically. Rapid mucosal healing occurred in all cases. The autografts conformed to the contour of the prosthesis and adequate tongue mobility was preserved. All mandibles remained stable throughout the follow-up period. Histologically, short villi covered the jejunal grafts to three months whilst at six months both normal and abnormal jejunal mucosal morphology was evident.

Animals↗
PubMed2001

[Prosthetic rehabilitation with endosseous implants in fibular free flaps reconstructed mandibles].

Mandibular defect following neoplasm resection involves severe alterations in morphology. Today, however, these alterations can be repaired with the use of revascularized free flaps. Chewing can be returned to normal, or at least to an acceptable level, thanks to the insertion of endosseous implants, used both to support the fixed prosthesis and the mobile prosthesis (overdenture). The present work reports the Authors' experience with 5 patients who underwent compound mandibular resection and reconstruction with revascularized fibula free flaps. In all cases the mandible was totally toothless and rehabilitation called for the insertion of a total prosthesis held by a bar secured to the endosseous implant. In 2 cases the implants were inserted at the time of reconstruction. Four patients completed the rehabilitation program, with a 93% (14/15) implant success rate. All were able to return to a normal diet. Likewise the aesthetic results were valid. The main problem was to achieve an adequate interface between the soft tissues and the implants.

Adolescent↗
PubMedDate not supplied

[Surgical and prosthetic treatment of large mandibular cysts].

This paper presents a combined surgical-prosthetic procedure of reconstructing mandibular bone defect in a 53 year old patient, following enucleation of a mandibular cyst (Cystectomy Partsch II). After a thorough diagnostic evaluation, a surgical procedure was planned with the particular attention to the nature of the disease, patient's condition, size and extension of the cyst, tissue loss, and the possibilities of prosthetic management of a mandibular bone defect with partial postresection dental prosthesis. It is of great importance to point to the significance of teamwork of a maxillofacial surgeon and a specialist in prosthodontics. This kind of cooperation provided very effective and less risky soft tissue, as well as bone tissue regeneration (osteogenesis). The patient's recovery was fast, and he could return to his daily activities and work without significant changes regarding quality of life after surgery and prosthetic treatment.

Denture, Partial↗
PubMed2004

Lip plumper prosthesis for a patient with a marginal mandibulectomy: a clinical report.

An intraoral prosthesis was fabricated to restore more normal contour to a patient's lower lip that was compromised following a marginal mandibulectomy performed to eradicate a malignant neoplasm. The surgical resection compromised the lower lip on the affected side because the marginal mandibular branch of the facial nerve was damaged during the surgical resection. The prosthesis successfully restored the lost lip support, reduced the incidence of lip biting, and improved the patient's oral competency. This clinical report describes the procedure for making an intraoral lip plumper prosthesis to improve patient esthetics and oral function.

Acrylic Resins↗
PubMed1999

[Experimental study on three-dimensional adjustable condyle prosthesis for reconstruction of temporomandibular joint].

OBJECTIVE: To study the possibility of reconstructing TMJ with a modified three-dimensional adjustable condylar prosthesis (TDACP). METHODS: The modified TDACP was placed immediately after resection of the mandibular ramus and condyle in 3 adult rhesus monkeys. The results were evaluated by radiography, histological and anatomical examinations, as well as chewing function at 3, 6, and 14 months after surgery. RESULTS: Through adjustment the condyle prosthesis could fit exactly, the functions were good, every part of the prosthesis was firm, the screws were osteointegrated, there was no adverse soft tissue reactions and no pathological changes in the TMJ of non-operated opposite condyle. Problems were: the distribution of fixation stress of screws was somewhat unreasonable, the downward sliding of the condyle was limited, there was erosion of the posterior slope of the glenoid fossa, and the articular disc could not keep its in situ place and function. CONCLUSION: The results suggests that the prosthesis needs further improvement.

Animals↗
PubMed2001

Double-coping technique in prosthesis fabrication for osseointegrated teeth implantation: case report.

Reconstruction of segmental mandibular defects resulting from trauma, infection, or tumor resection still remains difficult. Although cosmetic improvement was seen in patients who had immediate reconstruction of the mandibular continuity, normal mastication and deglutition could not be achieved by conventional removable dentures. Since 1988, the treatment protocol has been modified to use endosseous root-form implants to support dental prostheses instead of the conventional removable prostheses in these patients. There are 2 types of prostheses that can be constructed over dental implants: (1) a removable implant overdenture and (2) a fixed detachable prosthesis. Although the latter better meets in patients' psychological needs, it may present problems such as phonetic discrepancies, food impaction, difficult home care, and poor esthetics if the patient has a high lip line. In addition, it is not easy to fabricate accurately in the laboratory. To overcome these problems, a case is presented to illustrate the use of another fixed-type prosthesis, a double-coping technique, for fabricating dentures so that any discrepancy between the inner and outer copings can be filled by cement. The technique not only improves the shortcomings of fixed detachable prostheses but also satisfactorily meets patients' desire for normal mastication and deglutition. Follow-up after 4 years showed no significant changes around the implants by clinical and radiographic examinations.

Dental Implantation↗
PubMed1991

Combination of natural teeth and osseointegrated implants as prosthesis abutments: a 2-year longitudinal study.

Twenty-three patients with Kennedy Class I mandibular dentition were supplied with prostheses in the posterior parts of the mandible. On one side they were given a prosthesis supported by two implants (prosthesis Type I) and on the other side they received a prosthesis supported by one implant and one natural tooth (prosthesis Type II). Sixty-nine fixtures were inserted and 46 prostheses constructed. Eight of the fixtures were lost during the observation period. The failure rate of the implants was about the same in the two types of prostheses; five fixtures belonged to prostheses Type I (10.9%) and two fixtures belonged to prostheses Type II (8.7%), while one fixture was lost prior to loading. From a theoretical point of view, the combination of a tooth and an osseointegrated implant should encounter problems with regard to the difference in bone anchorage and there should be a risk of biomechanical complications. However, the results of this study did not indicate any disadvantages in connecting teeth and implants in the same restoration.

Adult↗
PubMed1990

[Mandibular reconstruction with the titanium-hollow screw-reconstruction plate system (THORP)].

The THORP system is designed for bridging mandibular defects and for internal osteosynthesis of mandibular fractures. The major aspects and advantages of the THORP system compared with the conventional reconstruction plates and screws are: 1. The rigid fixation of the head of the screw to the plate, thus avoiding unphysiological loads to the bone underneath the plate. 2. The titanium-plasma coated and perforated hollow screws enable the development of direct bone-titanium contact at the area of the thread as well as the ingrowth of bone into the lumen and perforations. Further advantages are the preservation of small fragments such as the condylar process with only two screws and the stable fixation of bone transplants. The specially designed freely adjustable condylar prosthesis guarantees a correct guidance and function of the lower jaw. The fixation of this system to the lingual aspect of the jaw is particularly significant avoiding decubitus and perforation of the skin in the chin area. The results and the complications of 141 reconstructions of the lower jaw are discussed.

Bone Plates↗
PubMed1995

Mandibular reconstruction using a titanium plate: the impact of radiation therapy on plate preservation.

PURPOSE: To evaluate the soft tissue and bone tolerance of radiation therapy (RT) in patients undergoing radical composite resection and mandibular reconstruction using a bridging titanium plate with myocutaneous flap closure. METHODS AND MATERIALS: From 1990 to 1994, 47 patients with primary or recurrent oral cavity or oropharyngeal carcinomas were treated with radical composite resection and mandibular reconstruction using a bridging titanium plate with myocutaneous flap closure. Eleven patients received no RT (no RT), 10 patients received RT greater than 10 months from the time of surgery (remote RT), and 26 patients received RT within 12 weeks of surgery (perioperative RT). The radiation dose to the reconstructed mandible ranged from 45 to 75 Gy (median 63 Gy). The effect of the titanium plate on the radiation dose was measured using film dosimetry and soft tissue and bone-equivalent materials. The median follow-up was 17 months (range: 3-50 months). RESULTS: Late complications included four patients with osteomyelitis or necrosis, two plate exposures requiring flap revision, one chronic infection, two cases of chronic pain, two fistulae, and one case of trismus and malocclusion. The crude incidence of late complications by treatment was: (a) no RT: 3 of 11 patients (27%); (b) remote RT: 2 of 10 patients (20%); and (c) perioperative RT: 9 of 26 patients (35%). One patient in the no-RT group lost the plate due to chronic pain. Five patients in the perioperative RT group also had plate loss, four due to osteomyelitis and/or necrosis, and one due to pain related to a recurrent tumor. No patients in the remote RT group had plate loss. The actuarial prosthesis preservation rate at 2 years was 88% for the no RT, 100% for the remote RT, and 57% for the perioperative RT groups (p = 0.05). Phantom dose measurements showed that for parallel opposed 6 MV photon beams, there was no significant increase in the dose proximal or distal to the plate in either a soft tissue- or bone-equivalent phantom. CONCLUSIONS: The impact of radiation therapy on plate preservation after mandibular reconstructive surgery using a titanium plate may be dependent on the timing of RT relative to surgery. Significantly more mandibular reconstruction plates were lost when the involved mandible received RT in the perioperative period than when RT was delivered beyond 10 months from surgery or when no RT was given. The use of alloplastic implants such as titanium plates in conjunction with myocutaneous flap coverage for mandibular reconstruction is attractive because it allows immediate reconstruction of the defect and promotes a good functional and cosmetic result; however, administration of perioperative RT may result in a higher plate failure rate.

Adolescent↗
PubMed1993

A new device for blockout procedures in rotational path removable partial dentures.

The rationale of a rotation axis is discussed and on this basis a blockout device is designed for rotational path removable partial dentures. This device has three basic components, which are (1) the acrylic resin block, (2) the rotation axis, and (3) the functional part. In the blockout procedures for removable partial dentures with tilted mandibular molars, the rotation axis of the prosthesis is first localized by the blockout device. A knife edge, made of Duralay resin that corresponds to the survey lines of teeth to be used as supports, is constructed and is joined to the functional part of the blockout device. Blockout regions are determined by the rotational movement of the Duralay resin knife edge along the rotation axis of the blockout device. In addition to the function of blockout, the device can also be used to analyze diagnostic casts for critical undercuts. Internal and external types of blockout devices are also discussed.

Acrylic Resins↗
PubMed2005

Thirteen-year follow-up of a mandibular implant-supported fixed complete denture in a patient with Sjogren's syndrome: a clinical report.

This clinical report describes the treatment and long-term follow-up of a patient with Sjogren's syndrome treated with osseointegrated implants and a mandibular fixed complete denture. The implants and prosthesis have remained stable and functional for 13 years. Implant treatment may, therefore, offer a viable long-term treatment alternative for patients with Sjogren's syndrome.

Aged↗
PubMed1992

Treatment of sleep apnea with prosthetic mandibular advancement (PMA).

Nine males with sleep apnea DOES syndrome and three males with sleep apnea DIMS syndrome were treated with prosthetic mandibular advancement (PMA). The method uses a prosthesis, which is designed to advance the mandible 3-5 mm to prevent upper airway occlusion during sleep. The apnea index in the obstructive-type apnea and the percentage of time spent in obstructive apnea decreased significantly with PMA. Although the apnea index showed merely a tendency to decrease in central apnea (p < 0.1), the percentage of time spent in central apnea decreased significantly with PMA. A marked improvement in sleep structures was observed with PMA; a significant increase was seen in total sleep time, percent slow wave sleep (SWS) and percent rapid eye movement (REM) sleep, and the time spent in intra-sleep awakening decreased remarkably. PMA had excellent effects on snoring, and daytime hypersomnolence was reduced in almost all patients. Moreover, a survey on the therapeutic effects of PMA on sleep apnea syndrome and problems associated with wearing PMA was performed with a questionnaire for the sample of nine DOES patients and an additional 22 patients who were treated over a long time. The therapeutic effects could be maintained without any problems in about 2/3 of these patients. The therapeutic mechanisms of PMA in its reduction of both obstructive and central apnea are discussed.

Adult↗