Biomedical subjects

Georg-Hubertus Nentwig

Publications and source records attributed to Georg-Hubertus Nentwig.

4 recordsLinked to original sources

PubMed2006

Incidence and predictive factors for perforation of the maxillary antrum in operations to remove upper wisdom teeth: prospective multicentre study.

BACKGROUND: Our aim was to evaluate the incidence of perforations of the sinuses and their related treatment after the removal of upper wisdom teeth depending on various anatomical and clinical variables. MATERIAL AND METHODS: A total of 1057 upper wisdom teeth were removed under local anaesthetic in the departments of oral surgery at the Universities of Bonn, Düsseldorf, Frankfurt and Mainz, Germany. Data were collected with the help of an anonymised questionnaire dealing with information about the patients, and the position and stage of the development of teeth, as well as the occurrence and size of an oro-antral communication and its treatment. RESULTS: Of 465 extractions and 592 osteotomies of the upper third molars, 134 interventions (13%) were related directly to the diagnosis of a perforated maxillary sinus. Acute oro-antral communication occurred as a result of the removal of completely impacted teeth in 88 of 370, (24%) by removal of partially impacted teeth in 23 of 222 (10%) and in fully erupted third molars in 23 of 465 (5%) of all cases. These differences are significant (p<0.001). In 111 (83%), the diameter of the oro-antral perforation was less than 3mm. In 25 (19%) of all sinus openings, a buccal sliding flap was used to close the extraction wound. We conclude that intraoperative fracture of the root, higher degree of impaction and higher age of the patient are associated with a greater likelihood of oro-antral perforation.

Adolescent↗

PubMed2006

Immediate versus delayed functional loading of implants in the posterior mandible: a 2-year prospective clinical study of 12 consecutive cases.

The aim of this investigation was to evaluate the clinical success of immediately loaded implants versus implants loaded in a delayed fashion in the posterior mandible. Three implants were placed distal to the canines bilaterally in the edentulous distal mandibular ridges of 12 patients. One side was randomly selected for placement of three implants (delayed loading; control sites) with a progressive thread design for submerged healing, and after 3 months the implants were exposed and loaded with provisional splinted crowns, which were replaced 6 weeks later by the definitive restorations. Three additional implants (immediately loaded; test sites), of the same size were placed in the contralateral side of the mandible. The test implants had abutments placed and were loaded immediately using the same protocol as the control implants. After a mean loading period of 25.3 months, the patients showed normal mean clinical values without significant differences (P < 0.05) for test and control implants, respectively, as follows: Plaque Index: 0.4 versus 0.8; Sulcus Bleeding Index: 0.5 versus 0.3; probing pocket depth: 1.9 mm versus 2.1 mm; width of keratinized mucosa: 2.5 mm versus 3.3 mm; Periotest value: -3.7 versus -3.2. Twenty-nine of the examined sites showed no bone loss. After 2 years of loading in the posterior mandible, test and control implants had the same prognosis.

Bicuspid↗

PubMed2003

Bone-implant interface around titanium implants under different loading conditions: a histomorphometrical analysis in the Macaca fascicularis monkey.

BACKGROUND: Bone healing around endosseous dental implants is associated with peri-implant loading conditions. Therefore, the aim of this study was to evaluate histomorphometrically the bone response around unloaded, delayed, and immediately loaded implants with a progressive thread design that were placed in the posterior regions of the lower jaw in monkeys. METHODS: Nine adult monkeys (Macaca fascicularis) were used in this study. After extraction of the second premolars and first and second molars in the mandible, the bone was allowed to heal for a period of 3 months. Forty-eight 8 mm long implants with a diameter of 3.5 mm were placed according to the following protocol. In two of the monkeys, six implants were placed and left to heal submerged for 3 months (group A). In seven monkeys, 21 implants were placed in one side of the mandible and loaded after 3 months of submerged healing (group B). The group B implants were loaded with temporary resin bridges at the same time as another 21 implants that were loaded immediately (group C) after placement in the contralateral side of the mandibles of the same monkeys. The occlusion of group B and C implants was checked for optimal relationship of the resin bridges that were replaced 1 month later with metal bridges and loaded for an additional 2 months. The group A animals were sacrificed after 3 months of submerged healing without loading; group B and C animals were sacrificed after 3 months of implant loading. Specimens were examined histologically and histomorphometrically. RESULTS: All implants osseointegrated without presenting any gap in the metal-bone interface. Compact cortical bone was found in contact with the implant surfaces. Group A implants demonstrated in the interface cancellous bone with loose connective tissue. Group B and C implants showed a thick cortical plate with extensive bone trabeculae formation. There was a significant difference in bone-to-implant contact (BIC) between the various loading conditions. No significant difference (P < 0.05) was found between groups B and C. There was an increased area of bone (BA) within the threads as well as around the apices of group B and C implants. CONCLUSIONS: Implant loading might have stimulated increased bone formation and thus may be a key factor in influencing positive osseointegration. In addition, immediately loaded implants may osseointegrate in a similar manner as delayed loaded implants.

Animals↗

PubMed2003

Peri-implant soft tissue integration of immediately loaded implants in the posterior macaque mandible: a histomorphometric study.

BACKGROUND: Today, one critical goal in implant placement is the achievement of optimal soft tissue integration. Reports thus far have demonstrated successful soft tissue preservation in delayed loaded implants placed in anterior jaws. The aim of this study was to histomorphometrically examine the soft tissues around immediately loaded implants placed in the macaque posterior mandible. METHODS: Splinted crowns on screw-shaped titanium implants (8 mm length, 3.5 mm diameter) were utilized. Three implants each were placed in the premolar-molar edentulous mandibular segments of 6 adult monkeys (Macaca fascicularis); one side served as the control (delayed loading) and the other as the test sites (immediate loading). The animals were sacrificed after 3 months of loading. Histomorphometry of 6 soft tissue indices including the sulcus depth (SD), junctional epithelium (JE), connective tissue contact (CTC), biologic width (BW = SD + JE + CTC), DIM (distance between the implant top and coronal gingiva), and DIB (distance between the implant top and first implant-to-bone contact) was performed on non-decalcified sections. RESULTS: No significant differences in the mean soft tissue scores (mm) between the test (SD = 0.68 +/- 0.63; JE = 1.71 +/- 1.04; CTC = 1.51 +/- 1.14; DIM = 2.27 +/- 1.18; DIB = 1.32 +/- 1.21; BW = 3.9) and control (SD = 0.88 + 0.57; JE = 1.66 + 0.77; CTC = 1.24 +/- 0.92; DIM = 2.38 +/- 0.81; DIB = 1.19 +/- 0.91; BW = 3.78) groups were observed (P > 0.01). CONCLUSION: These findings suggest that the dimensions of the peri-implant soft tissues were within the biologic range and were not influenced by immediate functional loading or posterior location of the implants in the macaque mandible.

Alveolar Process↗