Oral rehabilitation of tooth agenesis frequently starts in paediatric dentistry. A retrospective analysis of 625 patients.

AIM: As oral rehabilitation of tooth agenesis usually begins at a very young age, it is important to plan the therapy in advance in order to prepare the patient for the final treatment after the end of skeletal and dental growth. The diverse patterns of tooth agenesis require interdisciplinary oral rehabilitation adapted to individual factors like patient's age, number of missing teeth, and alveolar-bone development. The aim of the present high volume single-center study was to provide an overview of the management of patients with tooth agenesis, in terms of treatment approaches, associations, and long-term implant survival, over a period of 30 years. METHODS: Descriptive analyses were performed to analyse treatment approaches and and how they reated to severity of agenesis as well as patients' gender and age. Kaplan-Meier survival curves and log-rank-tests were used to investigate implant survival over time. CONCLUSION: Treatment starts usually in childhood or adolescence; orthodontic therapy was the most common treatment. All treatment options showed similar high survival rates. External bone augmentation might be a risk-factor for implant loss.

Atrophy of the residual alveolar ridge following tooth loss in an historical population.

OBJECTIVES: To study the natural aetiopathology of jaw atrophy after tooth loss, unaltered by prosthetic procedures, an historical population without modern dental treatment was examined. METHODS: Based on the hypothesis that there are predictable changes in shape during jaw-atrophy, frequency and degree of atrophy as well as clinical aspects of bone quality and resorption were determined in the skeletal remains of 263 individuals. The potential association between age and frequency/severity of atrophy was analysed. RESULTS: Atrophy in at least one jaw segment was present in 45.2% of the analysed jaw specimens. The residual ridge underwent a series of changes in shape and height following the pattern of resorption described for modern populations. The severity of these alterations was associated with the age of the individual and the region within the jaw. Atrophy was frequently related to structural degradation of the covering cortical layer. CONCLUSIONS: These findings prove that atrophy of the jaw evidently does occur, displaying similar patterns of resorption in a population without modern prosthetics, where the negative effect of ill-fitting dentures is excluded. The basic information about alterations of shape and the cortical layer covering the residual crest might help to provide a deeper insight into aetiopathological mechanisms of this common oral disease.

Characteristic features of trabecular bone in edentulous mandibles.

BACKGROUND: The density and architecture of the alveolar trabecular bone are crucial to the stability of an endosseous implant. A significantly higher implant failure rate can be expected when implants are placed in alveolar bone with reduced density and stability. Therefore, the present study aimed to describe the trabecular bone structure of edentulous mandibles. METHOD: Two hundred and seventy-eight bone sections, including the lateral incisor, first premolar, and first molar regions, were obtained from 128 edentulous lower jaws (68 females and 60 males; mean age: 77.58 years). Ground sections were prepared for each region using the 'sawing and grinding' technique. The following standard structural histomorphometric parameters were determined using a semiautomatic image analysis: trabecular bone volume, trabecular thickness, trabecular number, trabecular separation, and the trabecular bone pattern factor, which describes the connectedness of cancellous bone structures. Also, the maximum height of the jaw section was determined, to detect any possible correlations between vertical height and histomorphometric parameters. RESULTS: All the histomorphometric parameters examined showed an unexpectedly huge range of variation. The mean trabecular bone volume ranged between 20.9% and 36.9%. The mean trabecular thickness showed values between 165.9 and 224.7 microm. The mean trabecular number ranged between 1.22 and 1.77/ mm, and the mean trabecular separation ranged between 436.7 and 720.0 microm. The mean trabecular bone pattern factor showed values between -0.05 and -3.01/ mm. The maximum height of the jaw sections showed values between 16.05 and 23.42 mm. The trabecular bone volume, thickness, number and connectivity were significantly lower in the molar region than in the incisal and premolar regions. Significant sex-specific differences were found in all the regions, female mandibles showing a smaller amount and lower connectivity of cancellous bone than male mandibles. No correlation could be found between the maximum height of the jaw and the histomorphometric parameters of the cancellous bone. CONCLUSION: A possible explanation for the difference in the density between the incisal and the molar region may be that molars are generally lost at an earlier age than anterior and premolar teeth. As a result, atrophy-related resorptive and remodeling processes commence earlier and progress further in this region than in the anterior and premolar regions. Sex-specific differences are probably due to an increased postmenopausal bone loss of the females.

The symphyseal single-tooth implant for anchorage of a mandibular complete denture in geriatric patients: a clinical report.

Little information exists to define the minimum number of implants required for sufficient anchorage of mandibular overdentures. To date, 2 implants placed in the interforaminal region have been considered the minimum. The aim of this study was to examine whether a single symphyseal implant would suffice for adequate anchorage of a mandibular complete denture in elderly patients (octogenarians), and whether this surgically, prosthetically, and financially simple concept would also satisfy patients needing replacement of the mandibular dentition. Nine patients with a mean age of 82.2 years underwent placement of a single symphyseal endosseous implant and anchorage of a complete denture using a ball attachment. Standardized recall examinations, including patient response and inspections of the peri-implant soft tissue and bone conditions, were carried out at 3- to 6-month intervals for a period of 1 1/2 years. It was found that anchorage with a single implant led to both a significant improvement in patients' subjective satisfaction (P < .01) and a significant reduction in reported symptoms (P < .01). During the observation phase, pocket depth and bone resorption initially increased around implants but stabilized after the sixth month. Denture management (placement and removal) also improved during the recall period (P < .01). The results of this study indicate that oral rehabilitation by mandibular complete dentures anchored on a single implant can be considered an economical therapeutic alternative to a conventional mandibular complete denture for very old (octogenarian) patients.

Assessment of the blood supply to the mental region for reduction of bleeding complications during implant surgery in the interforaminal region.

Several life-threatening complications caused by hemorrhage that can occur during the placement of dental implants in the mandibular interforaminal region have been described in the literature. The aim of this study was to assess the vascular supply to this region and delineate the relative contribution and importance of the sublingual artery versus the submental artery. Thirty-four human cadavers were dissected. Special attention was directed to the presence of a branch of the submental artery that perforates the mylohyoid muscle and thus participates in the blood supply to the floor of the mouth together with the sublingual artery. A sublingual artery was found in 71% of the specimens. A large branch of the submental artery perforating the mylohyoid muscle was found in 41% of the specimens. The point of perforation was located an average of 31 mm posterior to the menton. The high risk of injuring the vessels of the floor of the mouth can be explained by the close vicinity of these vessels to the mandibular lingual cortical plate. To prevent complications in cases of unclear anatomic identification of the fossa sublingualis, preoperative lingual probing or elevation of the periosteum of the lingual aspect of the mandible is necessary. An alternative diagnostic procedure is precise preoperative noninvasive imaging (eg, computed tomography).

Sonographic imaging of the soft-tissue thickness of the edentulous maxilla.

For preimplantologic evaluation and diagnosis, there are various mechanical methods for measuring the thickness of the soft tissue and thus indirectly measuring the osseous bed of the implant. This study evaluated the use of real-time sonography for analyzing the soft-tissue thickness of the entire edentulous maxilla in an anatomic examination of human cadaver specimens. The data obtained were compared with findings from the usual needle measurement method. The ultrasound measurement method produced realistic data in all measurement points of all sectional planes selected.

Computed tomographic diagnosis and localization of bone canals in the mandibular interforaminal region for prevention of bleeding complications during implant surgery.

In this study, computed tomograms (CTs) of 70 patients were examined for visible vascular canals in the mandible as well as for their localization, incidence, diameter, and content. All patients examined showed at least 1 lingual perforating bone canal in the mandible. Since such vascular canals are encountered regularly, routine CT examination is recommended prior to implant surgery to help avoid severe bleeding complications during the placement of implants in the interforaminal region.

Incidence and suggested surgical management of septa in sinus-lift procedures.

A variable number of septa, also referred to as Underwood's septa, divide the floor of the maxillary sinus into several recesses and may thus cause various complications during sinus-lift procedures. The incidence of Underwood's septa was evaluated by examining 41 edentulous maxillas. In 13 of these maxillas (31.7% of the cases), sinus floors with at least one septum were observed. Most of the septa were located in the region between the second premolar and the first molar. A possible cause of septal formation could be the variable phases of maxillary sinus pneumatization of the empty alveolar process following tooth extraction.

Use of crestal bone for augmentation of extremely knife-edged alveolar ridges prior to implant placement: report of 3 cases.

A technique is presented for interforaminal lateral augmentation of mandibles with adequate bone height, but extremely knife-edged mandibular alveolar ridges (Class IV of Cawood and Howell's classification of residual ridges), in which the crestal portion of the knife-edged ridge is used as grafting material. Following an osteotomy and rotation of the grafts by 180 degrees, the grafts were fixed to the residual ridge below the osteotomy line by means of miniscrews. All grafts showed only mild resorption after a healing period of 3 months, and it was possible to place 4 implants in the now sufficiently wide host region.

Maxillary sinus septa: incidence, morphology and clinical implications.

This study was carried out to examine the incidence, morphology and clinical implication of antral septa. Out of 265 maxillary sinuses, 65 sinuses in atrophic maxillae were examined clinically during sinus floor elevation and 200 sinuses examined radiographically (CT), the latter being further subdivided into non-atrophic/dentate and atrophic/edentulous maxillary segments. Eighteen (27.7%) out of 65 clinically-examined maxillae and 32 (16%) out of the 200 non-preselected CT-examined maxillary sinuses showed antral septa. CT-topogram subclassification revealed 21 septa (13.2%) in 159 non-atrophic and 11 septa (26.8%) in 41 atrophic maxillary segments (P < 0.01). Morphologically, CT examination yielded one complete septum (0.5%), 21 incomplete septa on the sinus floor and 10 incomplete septa on the anterior antral wall (5%). CT revealed a significantly greater dimension of antral septa in non-atrophic maxillary segments than in atrophic ones (P < 0.01). In atrophic maxillary sinuses, the incidence (27.7% vs 26.8%), morphology (all septa located on sinus floor) and height (8.1 +/- 2.5 mm vs 6.8 +/- 1.6 mm) did not differ between the clinical and the CT examinations. Detailed knowledge about location, morphology and height of antral septa is clinically relevant to reduce the rate of complications when maxillary sinus surgery, i.e. sinus floor elevation, is carried out.

Magnetic resonance in lesions of the parotid gland.

In a prospective study the relevance of magnetic resonance (MR) for the diagnoses of tumors of the parotid gland has been evaluated. Due to the excellent soft tissue contrast and also the possibility of imaging in various planes and sections and to the high resolution achieved by surface coils, it was possible to visualize the lesions and the surrounding anatomy in great detail. MR combines the advantages of ultrasound and computed tomography and is indicated if a tumor cannot be defined sharply by using ultrasound or CT.

Effects of reduced mouth opening capacity (trismus) on pulmonary function.

In this study, pulmonary function test data were obtained from 15 healthy volunteers and 15 patients with slightly impaired ventilation during both normal and maximally reduced opening of the mouth (trismus, intercuspal position). The aim of the study was to examine the effects of complete trismus on pulmonary function using objective and subjective parameters. In maximally reduced mouth opening, both groups showed an impairment of all subjective and objective pulmonary function test data. In healthy volunteers, the significant changes in test data (P<0.05) stimulated mild to moderate pulmonary impairment, whereas patients with an already impaired pulmonary function showed a marked deterioration of their initial respiratory condition. The results of the subjective and objective parameters examined indicate that an intercuspal position (trismus) further aggravates pulmonary functional impairment. Complete trismus can be considered a risk factor to pulmonary function in patients using mouth breathing as a primary or supportive mode of respiration.

The edentulous maxillary alveolar process in the region of the maxillary sinus--a study of physical dimension.

From 47 anatomic specimens, vertical sections were cut in the molar region, and computer-assisted measurements of both height and width of the alveolar ridge were made to assess the available bone volume for endosseous implant placement. The mean ridge heights ranged between 9.30 and 3.23 mm, the highest and lowest values being 13.8 and 0.8 mm, respectively. The ridge widths generally proved to be sufficient for placement of endosseous implants. Small knife-edge ridges are rarely found in the posterior maxilla. Reduction of the cancellous portion of the posterior maxilla seems to be influenced by the duration of edentulousness, as well as by osteoporotic changes, without being directly related to ridge configuration and bone volume.

Treatment of patients with extreme maxillary atrophy using sinus floor augmentation and implants: preliminary results.

Twenty consecutive patients with extreme maxillary atrophy underwent bilateral sinus floor augmentation, either with autogenous bone from the iliac crest or with a combination of autogenous bone and hydroxyapatite. One patient was treated using autogenous bone from the chin region. After a period of three to eight months, three to four implants were placed in each posterior maxilla. Only 10 out of 155 inserted implants were located in the anterior non-augmented maxilla. During the observation period of one to six years, four implants (one of them located in the anterior maxilla) had to be removed prior to prosthetic treatment. Another three implants were lost during the follow up period. This corresponds to a Kaplan-Meier survival probability of 95.4% after 70 months. No statistically significant difference in implant success was observed between women and men (P=0.16). All prosthetic suprastructures are still in function despite these implant losses. Mean peri-implant bone resorption was 1.34 mm with no statistically significant difference between implants placed more mesially and those placed more distally in the augmented area, though a trend could be observed (P=0.058) for a more pronounced bone resorption around implants placed in the premolar region. When a mean mesial and distal bone resorption of >2 mm was considered in the calculation of the success prognosis, the survival probability dropped to 74.7% after 70 months.

Sonography of nonneoplastic disorders of the salivary glands.

We examined 637 patients with salivary gland disorders by real-time sonography. In 270 patients, the possibility of neoplasia of the salivary glands could not be excluded by ultrasound. In the remaining 367 patients, the following disorders were diagnosed sonographically: acute inflammation (72 patients), Sjögren's syndrome or chronic inflammation (81 patients), abscess (9 patients), sialolithiasis (192 patients), and cysts (13 patients). The present study discusses the ultrasound appearances of a variety of diseases and the indications and limits of sonography in the evaluation of salivary gland pathology.

Complications of sinus perforations and their management in endodontics.

The intimate position of the maxillary sinus to the apices of teeth creates problems if periapical inflammation occurs. This can lead to a perforation into the sinus and cause sinusitis. Persistent and complicated situations that do not respond after nonsurgical root canal treatment demand a suitable surgical therapy. Knowledge of the specific anatomic conditions, an adequate diagnosis, and an appropriate surgical procedure facilitate success rates that are comparable with those obtained in other regions, even in unfavorable initial conditions.

[Anatomic-roentgenologic study of the mandibular canal in atrophic mandible]. / Anatomisch-röntgenologische Studie über den Canalis mandibulae im atrophen Unterkiefer.

This study analyses the changes observed with atrophy of the mandibular foramen and mental foramen, as well as the mandibular canal. All 43 left halves of the examined mandibles were systematized according to the classification of the reduction of residual ridges by Atwood. This classification allows a precise description of the rate of atrophy. An evaluation of the results of computed tomography and X-ray, as well as measurements of the mandibles showed a number of significant atrophic changes. With extreme reduction of residual ridges the mental canal is significantly shortened. Increasing atrophic change causes the mental foramen to approach both the alveolar ridge and the basic tangent line. The distance of the mandibular canal to the lingual and buccal surface remains constant, whereas the distance to the cranial and caudal surface is markedly reduced according to the degree of atrophy. The mass of compact and spongy bone tissue is reduced to a level of 50% or less of the original volume. In general, the cortical lamina around the mandibular canal is more often found on the caudal side than on the cranial side. At extreme rates of reduction of residual ridges the mandibular canal is enclosed by compact bone tissue. The visibility of the mandibular canal and the mental foramen on X-ray is significantly reduced by extreme rates of resorption.

[Stimulation of platelet mitogen-induced prostaglandin I2 synthesis in periodontal tissue of cyclosporin A treated patients]. / Stimulation der Plättchenmitogen-induzierten Prostaglandin I2-Synthese in periodontalem Gewebe von Cyclosporin A-behandelten Patienten.

Cyclosporine A (CsA) is a highly potent immunosuppressive agent that has proven to be particularly useful in organ transplantation. Like phenytoin and the calcium antagonists, this drug may be associated with gingival hyperplasia. This study examined the interaction of platelet derived growth factor (PDGF) with prostaglandin I2 (PGI2)--a potent mediator in inflammation and bone resorption. PGI2 synthesis was examined by bioassay in gingival tissue from rats, rabbits and humans. Gingival tissue from CsA-treated patients generates less PGI2. PDGF causes a dose-dependent increase in PGI2 release in both CsA-treated and control subjects. The actual and percentage increase in PGI2 synthesis, however, was significantly higher in control tissue. While PDGF on the other hand modulated cellular proliferation, it causes on the other hand liberation of PGI2 from gingival tissue, thus interfering with its own action and further synthesis. If the PGI2 response is insufficient as after CsA therapy, the proliferative action might dominate. These findings therefore suggest an important pathogenetic role of PDGF and possibly other growth factors in CsA-induced gingival hyperplasia. "CsA gingivitis" seems to be a predominantly proliferative process, whereby inflammatory reactions appear only as a secondary phenomenon.

Location of the mandibular canal within the atrophic mandible.

In 43 edentulous, lower jaw halves, sections were carried out in the area between the mental foramen and the third molar. The relative changes in the location and course of the mandibular canal which are caused by atrophy were analysed. For this purpose, the mandibles were classified according to so-called residual ridge orders which describe the different stages of alveolar ridge resorption. The following findings were obtained: The distance between the mandibular canal and the lingual and buccal external border does not change in any stage of the atrophic process, i.e. it remains conspicuously constant. However, the distance between the mandibular canal and the cranial and caudal borders of the body of the mandible partly changes to a statistically highly-significant extent, the distance between the canal and the atrophic alveolar ridge being affected more strongly than that between the canal and the base of the mandible. These changes were most clearly pronounced in the area of the first molar.

Reproducibility of three-dimensional CT-assisted model production in the maxillofacial area.

In the mid-eighties, computerised tomography (CT) assisted three-dimensional imaging, and modelling of skull structures was introduced into preoperative diagnosis in maxillofacial surgery. This new method is already being used in the preoperative planning of corrections of post-traumatic defects and craniofacial deformities as well as in tumour surgery and implantology. The aim of the present study was to collect information on the reproducibility of a skull model milled from hardened polyurethane foam, and based on the CT data of a real skull. Thirty one measurements were carried out on the model and on the original skull, leading to the result that the model showed a mean inaccuracy of 1.5 mm. The deviations ranged between 0.0 and 3.6 mm. Generally, the model structures, however, tended to be larger than those of the original. As far as the total of all measurements is concerned, the model deviated from the original skull by 1.6%. A convincing aspect of the model, which cannot be obtained by any other method, is its plasticity and the possibility of 3-D orientation on a lifesize model. However, the study indicates that surgeons using this technique should consider the possible discrepancies between the model and the real skull when making preoperative assessments.