Isolated Hypoglossal Nerve Palsy as an Early Symptom of a Granular Cell Tumor.

BACKGROUND: Hypoglossal nerve palsy (HNP) is rather common as a neurological disease. However, as an isolated nerve palsy it is an exceedingly rare phenomenon and points at local pathologies along the peripheral course of the nerve. In this communication we report a granular cell tumor (GCT) arising in the submandibular segment of the hypoglossal nerve. CASE-REPORT: Spontaneous isolated HNP was recognized in a female patient. First line MR-imaging identified a clivus-chordoma. However, involvement of the hypoglossal nerve was highly unlikely according to MR-findings. Finally, ultrasonographic investigation revealed a small submandibular mass which, at histological examination, turned out to be a granular cell tumor arising within the hypoglossal nerve. CONCLUSIONS: This is the report of an extremely rare GCT originating within the 12th cranial nerve. The case illustrates that isolated motoric cranial nerve palsy may result from this rare tumor entity. This report also points out the diagnostic value of a simple ultrasonographic investigation to depict pathologic lesions of the submandibular space.

Predictive values of resonance frequency analysis as a diagnostic tool in palatal implant loss.

OBJECTIVES: To determine the diagnostic value of resonance frequency analysis (RFA) in predicting palatal implant (PI) loss. MATERIALS AND METHODS: RFA values of 32 patients (study center at Mainz and Dresden) were evaluated in a prospective randomized controlled trial addressing clinical performance of two loading concepts on PI (Orthosystem, Straumann, Basel, Switzerland). Group 1: conventional loading after a 12-week healing period vs group 2: immediate loading within one week after insertion. Stability was assessed by RFA after surgical insertion (T1), one week (T2), and 12 weeks (T3) later. RESULTS: All 32 PI were clinically stable after surgical insertion; 14 PI were loaded conventionally and 18 immediately. One implant in group 1 was lost 6 weeks after insertion. One drop-out was registered in group 2. One false positive and three false negative implant stability quotients (ISQ) were observed. ISQ values of clinically stable PI in group 1 were 67.2 (SD ± 9.5) at T1, 62.3 (SD ± 11.7) at T2, and 68.2 (SD ± 5.5) at T3. Group 2 showed 67.1 (SD ± 11.7) at T1, 65.4 (SD ± 10.4) at T2, and 72.3 (SD ± 5.6) at T3. Differences between groups were not statistically significant for starting time (P = .88) and change from T1 to T2: 0.08 but were significant from T1 to T3: P = .04; (regression analysis). CONCLUSIONS: RFA had no sensitivity for prediction of stability. General decrease after primary stability and increase with secondary stability gives support for specificity. Within the limits of the study, only the diagnostic value of RFA identifying stable palatal implants could be confirmed.

Influence of soft tissue grafting, orofacial implant position, and angulation on facial hard and soft tissue thickness at immediately inserted and provisionalized implants in the anterior maxilla.

BACKGROUND: Resorption of hard and soft tissues following immediate implant insertion is frequently reported. Data regarding the influencing factors on facial tissue thickness are rare. PURPOSE: This retrospective study investigated the impact of connective tissue grafting, the orofacial angulation and position of immediately inserted and provisionalized implants on the facial hard and soft tissue thickness in the anterior maxilla within a 1- to 5-year follow-up. MATERIAL AND METHODS: Implants with the prerequisite of having preoperative and postoperative cone beam computed tomography (CBCT) and a follow-up of 1 to 5 years were included. Facial bone deficiencies were grafted flaplessly with autogenous bone in all sites. In a subgroup of implants additional connective tissue grafting was performed, whereas the remaining implants were not grafted with soft tissue. The orofacial tooth and implant angulation, the change of horizontal position and the facial bone thickness were measured by CBCT, the facial mucosa thickness by an ultrasonic device. RESULTS: In total, 76 implants were placed in 55 patients. Sixty-nine sites showed a facial bone defect. Thirty-eight received a connective tissue graft additionally. All implants were still in function after a mean follow-up of 36 months. The mean thickness of the facial mucosa was 1.72 mm at 1 mm, 1.63 mm at 4 mm, 1.52 mm at 6 mm, and 1.66 mm at 9 mm apically to mucosal margin. The bone thickness was 0.02, 0.25, and 0.36 mm initially and 1.32, 1.26, and 1.11 mm finally at 1, 3, and 6 mm apically to implant shoulder level. Mixed model analysis revealed an impact of the preoperative bone status on the facial bone increase. The facial soft tissue thickness was significantly influenced by the gingival biotype. CONCLUSIONS: The results indicate that an initial severe hard tissue defect allows for significant bone regeneration. The facial soft tissue thickness is primarily influenced by the gingival biotype.

Immediate and flapless implant insertion and provisionalization using autogenous bone grafts in the esthetic zone: 5-year results.

OBJECTIVES: As the 2-year results for immediately inserted and provisionalized implants have been reported, it remained an open issue, whether the initially high success rates and the esthetic outcome remain stable for longer observation periods. Therefore, this prospective study examines the 5-year hard and soft tissue changes at implants placed in the anterior maxilla. MATERIAL AND METHODS: Meanwhile, 37 microthreaded implants were placed in 21 patients into extraction sockets with and without facial bone deficiencies by a flapless approach. Facial gaps and bony defects were grafted with autogenous bone chips. The implants were immediately provisionalized. The primary outcome parameters were the interproximal marginal bone level and the thickness of the facial bony wall. Implant success and Pink Esthetic Score (PES) were considered as secondary outcome parameters. RESULTS: Two patients with four implants withdrew from the study (dropouts), and the remaining 33 implants were still in function at a follow-up period of 68 months. Marginal bone height averaged 0.04 mm coronal to the implant shoulder. The thickness of the facial bony lamellae increased significantly between pre-op examination and 1-year follow-up (p = .002) and thereafter remained stable. Within 5 years of follow-up, 24 of 33 implants were clinically stable, free of signs and symptoms, and showed bone loss less than 1 mm. The mean PES ratings improved slightly from 10.7 pre-operatively to 11.7 at the last follow-up (p = .02). CONCLUSIONS: Interproximal marginal bone levels, survival rates, and esthetic results remain stable at the 5-year follow-up in implants used in an immediate insertion, reconstruction, and provisionalization concept. Facial marginal bone levels decreased slightly; however, this reduction did not affect the PES so far.

Clinical and esthetic outcome with immediate insertion and provisionalization with or without connective tissue grafting in presence of mucogingival recessions: A retrospective analysis with follow-up between 1 and 8 years.

BACKGROUND: Recessions following immediate implant insertion are frequently reported in the literature. Data regarding implant installation in presence of mucogingival recessions are rare. PURPOSE: This study observes soft tissue level changes following immediate implant insertion and provisionalization of implants with or without connective tissue grafts in the anterior maxilla in patients with initial mucogingival recession within a follow-up period between one and eight years. MATERIALS AND METHODS: Twenty-six patients with marginal gingival recessions, which were designated for extraction and immediate implant insertion in the anterior zone of the maxilla (13-23), were included. Out of a larger group of immediate implants only single tooth replacements with 1 to 3 mm recession and a pre- and post-op CB-CT were selected. Facial bone deficiencies were grafted flaplessly with autologous bone in all sites. In a group of 13 patients the recessions (mean 2.3 ± 0.7 mm, range 1.0-3.0 mm) were grafted additionally by connective tissue (ABG + CTG), in the remaining 13 patients no soft tissue grafting (mean recession 1.8 ± 0.6 mm, range 1.0-3.0 mm) was performed (ABG). The marginal hard and soft tissue level, the width of the keratinized mucosa, the PES, and implant success were evaluated. RESULTS: After a mean follow-up period of 45 months the recessions were significantly reduced in the ABG group from 1.8 to 0.9 mm. The improvement was even more pronounced in the ABG + CTG group (from 2.3 to 0.5 mm). The PES improved significantly in both groups. At final examination all implants were still in function. Within the observational period, in 5 of 13 implants a marginal bone loss of more than 1 mm was noticed in the ABG, but in none of the ABG + CTG group. CONCLUSIONS: These clinical results provide evidence that immediate implant placement might improve the facial soft tissue level. This was more evident in cases with a greater recession and an additional treatment with connective tissue grafts.

Premolar autotransplantation in juvenile dentition: quantitative assessment of vertical bone and soft tissue growth.

OBJECTIVE: Premolar autotransplantation represents an effective therapeutic option for the treatment of juvenile dentition with either aquired or congenital hypodontia. The objective of this prospective clinical study was to quantitatively assess bone and soft tissue levels after autogenous premolar transplantation by clinical and radiographic parameters. STUDY DESIGN: In the study, 26 premolars were transplanted in 20 patients after traumatic tooth loss (n = 16) or congenital aplasia (n = 10) in the anterior maxilla. Based on standardized photographic documentation, the relative soft tissue level was measured compared to the healthy adjacent teeth. Radiographic findings included evaluation of root resorption, pulp canal obliteration, and relative bone height. RESULTS: Average survival rate of transplanted premolars (n = 26) was 100% over a follow-up period of 29 months (range 10-60 months). The relative soft tissue level significantly increased by +1.1 mm (P < .01). Radiographs showed a tendency toward vertical bone growth. Continuous root development and signs of pulpal healing were observed postoperatively in 18 transplants (69.2%). CONCLUSIONS: Autogenous premolar transplantation represents a safe method to ensure functional and aesthetic rehabilitation in the anterior maxilla irrespective of the nature of tooth loss.

What is the best position for palatal implants? A CBCT study on bone volume in the growing maxilla.

OBJECTIVE: The objectives of the present study are the following: (a) to investigate limitations (bone height, proximity to nasopalatine nerve and roots) in juvenile patients, (b) to review the recommended site for surgical insertion (level of the maxillary first premolars), and (c) to reassess the rationale behind the manufacturer's age limitation (12 years). PATIENTS AND METHODS: Cone beam CT images of 100 patients aged 10 to 20 years were analyzed. Vertical bone heights were measured in the median plane as well as 3- and 6-mm paramedian along the prospective axis of insertion, at the level of the first premolars (level 0), 3 mm anterior (level 1) and 3 mm posterior (level 2). The Mann-Whitney U test was used to compare bone heights between gender groups. RESULTS: The risk of damage to the nasopalatine nerve is highest in the median region on level 1 (46 %). The risk was lowest in the midsagittal region on level 0 (recommended insertion site; 3 %) and level 2 (0 %), as well as paramedian on levels 0 and 2. The risk of damaging roots was irrelevant for median insertion at all levels; the only critical region was 6-mm paramedian on level 1. CONCLUSIONS: The recommendation of surgical insertion at the level of the maxillary first premolars is still justified, but a slightly more posterior implant position might improve safety. We found no relevant growth-related changes in the vertical bone heights in the median palatal area. Thus, our data do not support the strict 12-year age restriction for palatal implants.

Third Molar Complications in the Elderly-A Matched-Pairs Analysis.

PURPOSE: The aim of this study was to evaluate the perioperative morbidity of third molar (3M) removal in elderly patients in an attempt to estimate the long-term future burden of 3M-related morbidity resulting from the postponement of 3M surgery to old age. MATERIALS AND METHODS: The study design was a retrospective matched-pair analysis comparing patients at least 65 years old (group A) with a control group of 15- to 20-year-old patients (group B). Age group was the predictor variable in this study. Outcome variables were general health status as defined by the modified Charlson score (MCS) and the American Society of Anesthesiologists (ASA) score, general surgical risks from antithrombotic or antiresorptive medication, and specific local surgical risks and complications. RESULTS: Patients in group A showed substantially more comorbidities as reflected in significantly higher MCS and ASA scores (P < .001). Older patients more frequently used antithrombotic agents (P < .001), had higher rates of ankylosis (P < .001) and nerve proximity (P < .001), and showed significantly more in intra- and postoperative complications (P < .001), thus resulting in longer operations and a substantially longer hospital stay (P < .001). CONCLUSION: Within the limits of a non-epidemiologic approach, this study showed a substantially greater burden of morbidity and substantially worse outcome of 3M surgery in older adults compared with young adults. For the medical risks of an aging population, the present data suggest a veritable burst of 3M-associated morbidity when surgery is shifted to late adulthood.

Moving the mandible in orthognathic surgery - A multicenter analysis.

Orthognathic surgery has always been a classical focus of maxillofacial surgery. Since more than 100 years, various surgical techniques for mandibular repositioning have been developed and clinically tested. Since the establishment of plate and screw osteosynthesis, orthognathic surgery became more stable and safe. Nowadays, different surgical methods for mobilising the mandible are existing. This international multicenter analysis (n = 51 hospitals) is providing first evidence based data for the current use of different surgical methods. The dominating techniques were Obwegeser/dal Pont (61%) followed by Hunsuck/Epker (37%) and Perthes/Schlössmann (29%). The main osteosynthesis materials were plates (82%), bicortical screws (23.5%), or a combination of both (5.9%). 47% of all centers reported to use several surgical methods at the same time, depending on the anatomical problem and the surgeon's preference. This shows that different surgical methods seem to work as comparable, safe, and reliable procedures in everydays clinical practise. On this basis, further prospective studies could evaluate possible advantages for our patients.

Clinical parameter of odontoma with special emphasis on treatment of impacted teeth-a retrospective multicentre study and literature review.

OBJECTIVES: Odontoma-separated into complex (CxOD) and compound (CpOD) subtypes-represents the most frequent odontogenic malformation. Retention of permanent teeth is a common symptom. Therefore, in a series of odontomas, an analysis of the management of retained teeth was conducted. MATERIALS AND METHODS: In a retrospective multicenter study of two University Medical Centers and one private praxis in Germany, demographic and clinical data regarding odontomas from 01/2000-03/2015 were obtained. In particular, the influence of operative therapy on the dentition and on the treatment of impacted teeth was analyzed. RESULTS: Forty-five patients with 15 CxOD and 30 CpOD were included. Initial symptoms were delayed eruption of permanent teeth (n = 11), pain (n = 4), and swellings (n = 2); 28 cases were discovered by incidence, all of them via panoramic radiographs. The mandible/maxilla ratio was about 1:0.55 (29/16). Thirty-five out of 45 odontomas were in close proximity of at least one tooth (n = 16 at molars). A total of 14 teeth were extracted (CxOD: n = 5; CpOD: n = 9). Extractions had to be conducted more often in older patients (mean age 39.8 vs. 25.6 years). Of the non-extracted teeth, 8 teeth were displaced and retained. Of those, 4 teeth were aligned in the dental arch via orthodontic help and 2 teeth erupted spontaneously after operation during the follow-up period. In all cases, no relapse was seen. CONCLUSION: Odontomas can cause displacement as well as malformation and resorption of the adjacent teeth. CLINICAL RELEVANCE: Mostly, removal of odontomas is conducted. Extirpation of odontoma can allow for normal tooth eruption, often rendering extractions avoidable. Orthodontic alignment, though sometimes challenging, is a reasonable therapeutic option. These findings underline the value of the panoramic radiograph in preventive dentistry in younger patients.

Immediately provisionalized OsseoSpeed(™) Profile implants inserted into extraction sockets: 3-year results.

OBJECTIVES: A sloped shoulder might improve the congruence between extraction socket and dental implant and may add to a better circumferential support of the peri-implant structures. Therefore, this study evaluates the 3-year clinical outcome (survival and success rates, marginal bone levels, and Pink Esthetic Score (PES)) of immediately inserted and provisionalized OsseoSpeed(™) Profile implants in the anterior maxilla. MATERIAL AND METHODS: Twenty-one implants were inserted in 16 patients. All implants were immediately placed into extraction sites with and without facial bone deficiencies. A flapless procedure was utilized, and the implants were provisionalized immediately. Facial gaps were grafted with autogenous bone chips from the mandibular ramus. Implant survival and success, the interproximal bone levels, the thickness of the facial bony wall, and the PES were evaluated. RESULTS: After a mean follow-up period of 43 months, 19 implants were still in function. One patient with 1 implant did not follow the study protocol (dropout) and 1 implant was lost at 10 weeks. Interproximal marginal bone levels measured -0.2 ± 0.4 mm (range, -1.0-0.4 mm) apical to the implant shoulder. The mean PES ratings were 11.9 ± 1.4 (range, 8-14) at the final examination. CONCLUSIONS: Clinical and radiographic results provide evidence that sloped implants can preserve the marginal bone circumferentially and are able to maintain soft tissue esthetics when inserted and provisionalized immediately, even in the presence of facial bony wall defects.

The current state of facial prosthetics ­ A multicenter analysis.

Even though modern surgical techniques are dominating reconstructive facial procedures, the capability to use facial epitheses for reconstruction is still an important skill for the maxillofacial surgeon. We present an international multicenter analysis to clarify which techniques are used to fixate facial prostheses. We contacted all maxillofacial departments in Germany, Austria, Switzerland and Norway which were registered with the German society for oral and maxillofacial surgery (DGMKG). These centers were asked via electronical mail to provide information on the type of epithesis fixation systems currently in use. The return rate from 58 departments was 43.1% (n = 25). Overall, implant fixation was the preferred fixation system (92%). Plates were the second most common fixation technique (32%). No centers reported the standard use of non-invasive fixation techniques for permanent epithesis fixation. The main retention systems in use were magnets (24/25), other retention systems are used much less often. The current preferred fixation technique for facial epitheses consists of implant-based, magnet-fixated epitheses. For nasal prostheses, a plate-based, magnet-fixated system is often used.

Life-threatening bleeding after tooth extraction due to vascular malformation: a case report and literature review.

Severe hemorrhages of the oral cavity may be caused by arteriovenous malformations. This case report concerns a 52-year-old healthy female who presented with a painful lower third molar and an extensive arteriovenous high-flow malformation of the floor of the right side of the mouth. During the extraction of the right lower wisdom tooth, an episode of massive life-threatening bleeding occurred. Since the therapy for intraoral arteriovenous malformations of the soft tissue is complex and often difficult to perform, the modus operandi of the present case is presented, and a review of the literature is included.

Maintenance of marginal bone support and soft tissue esthetics at immediately provisionalized OsseoSpeed implants placed into extraction sites: 2-year results.

BACKGROUND: Placement of implants into extraction sockets targets the maintenance of peri-implant hard and soft tissue structures and the support of a natural and esthetic contour. The main advantages of immediate implant insertion in comparison with delayed implant placement protocols are as follows: a reduced treatment time, less number of sessions, and, thus, the less invasive procedure. This study examines the clinical performance (survival rate, marginal bone levels and Pink Esthetic Score [PES]) of OsseoSpeed implants placed into extraction sockets with immediate provisionalization in the anterior maxilla after a follow-up of at least 12 months. METHODS: Twenty patients received a total number of 37 OsseoSpeed implants which were immediately inserted into extraction sockets with or without facial bone deficiencies of various dimensions. A flapless procedure was applied, and the implants were immediately provisionalized with temporary crowns without occlusal contacts. Facial gaps between implant surface and facial bone or the previous contour of the alveolar process were grafted with autogenous bone chips. Implants in diameters 3.5, 4.0, 4.5, and 5.0 with lengths of 11-17 mm were used in the study. During the course of the study, interproximal marginal bone levels, the thickness of the facial bony wall, implant success rate according to the criteria established by Buser, and the PES were assessed per implant. RESULTS: One patient with three implants did not continue the study after prosthesis delivery, the remaining 34 implants were still in function at the final follow-up (survival rate: 100%). The mean follow-up period was 27 months (range, 12-40 months). Marginal bone height at the level of the implant shoulder averaged -0.1 ± 0.55 mm (range, -1.25 to 1.47 mm) at the final follow-up. The mean PES ratings were 11.3 ± 1.8 (range, 6-14) at the final follow-up. In 78% of the patients, the PES was preserved or even improved. CONCLUSIONS: Success rates, marginal bone levels, and esthetic results suggest proof of principle for the preservation of marginal bone height at immediately placed and provisionalized OsseoSpeed implants after a follow-up of at least 12 months. Even implant sites with facial bony deficiencies can be successfully treated with a favorable esthetic outcome using the immediate implant insertion, immediate reconstruction, and immediate provisionalization technique.

Oral squamous cell carcinoma in the vicinity of dental implants.

OBJECTIVES: The study at hand presents a cohort of patients treated for carcinomas in the vicinity of dental implants for identification of potential risk factors. MATERIALS AND METHODS: The retrospective analysis covers patients treated for peri-implant carcinoma at our department between 1995 and 2011. An additional literature search focused likewise on peri-implant carcinomas. Obtained articles were screened for relevant risk factors and discussed in relation to our patient cohort. RESULTS: Fifteen patients were treated for peri-implant carcinoma. Six reported ongoing alcohol/tobacco consumption. Nine had a previously reported carcinoma of whom six had received radiotherapy after surgery. Time from implant placement until carcinoma diagnosis was 53.4 months on average. The literature search revealed 25 patients with peri-implant carcinoma and one with a sarcoma. Eight patients reported alcohol/tobacco consumption. Most patients exhibited risk factors for possible malignant transformation: previous carcinoma (n = 12), lichen (n = 4), irradiation (n = 3), and leukoplakia (n = 3). The average time until diagnosis was 51.6 months. CONCLUSIONS: Smoking, alcohol consumption, and the history of previous carcinoma characterize patients at risk for a peri-implant carcinoma. A balanced gender ratio might point at a higher risk for woman and additional risk factors promoting carcinogenesis apart from tobacco and alcohol consumption, a novel finding that has to be proven by larger patient counts. CLINICAL RELEVANCE: The incidence of carcinomas next to dental implants is low but may attain clinical relevance with raising implant figures worldwide. Patients at risk potentially profit from individualized recall intervals and careful evaluation.

Immediate nonfunctional loading of NobelPerfect implants in the anterior dental arch in private practice--5-year data.

BACKGROUND: The concept of scalloped implants to maintain the natural contour of the alveolar ridge has been a source of controversy for many years. PURPOSE: This study examined the long-term clinical performance of the scalloped NobelPerfect implant in a one-stage procedure (immediate loading in the esthetic zone). MATERIALS AND METHODS: In 20 patients, immediate prosthetic restorations were placed on 31 NobelPerfect implants in a private practice and followed for up to 78 months. Twenty-one implants were placed immediately after extraction, seven implants were placed after osseous consolidation of the extraction sockets, and three implants were placed secondary to extended alveolar ridge augmentation procedures. All implants were provisionalized on the day of implant placement and adjusted to clear all contacts in centric occlusion and during eccentric movements. Outcome variables were success rates, marginal bone levels, and pink esthetic score (PES) assessed per implant. RESULTS: One implant failed after 1.4 months. Five patients with six implants in total were scored in the 5-year follow-up as dropouts. Mean follow-up period of remaining 24 implants was 65 months (range, 55-78 months). Cumulative success rates according to the criteria specified by Smith and Zarb were 96.8%. Marginal bone levels averaged 1.1 mm above the first thread. Mean PES ratings were 10.5 (range, 3-13). CONCLUSIONS: Survival rates, marginal bone levels, and esthetic results suggest proof of principle for the preservation of the interproximal bony lamella with a scalloped implant design in long-term data.

ΔNp63 expression in four carcinoma cell lines and the effect on radioresistance--a siRNA knockdown model.

OBJECTIVES: This study investigated the expression of ΔNp63α in carcinoma cell lines of the upper aerodigestive tract and their potential influence on radioresistance using a small interfering RNA (siRNA) knockdown approach. MATERIALS AND METHODS: Four carcinoma cell lines were investigated for the expression of the ΔNp63 isoform by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) (0, 24, 48 h) with and without single dose irradiation of 6 Gy. Furthermore, all cell lines were transfected with siRNA against the ΔNp63α isoform over 24 h. Knockdown effectiveness was controlled by qRT-PCR and Western blot. Apoptotic events were evaluated by terminal transferase dUTP nick end labeling (TUNEL) assay and cross-checked by a test for cell viability (WST-1, Roche) over 48 h. RESULTS: All cell lines presented varying expression of the ΔNp63α isoform with and without irradiation. A sufficient knockdown rate was established by siRNA transfection. Knockdown of the ΔNp63 isoform showed an effect on radiation sensitivity proven by an increase of apoptotic events detectable by immunofluorescence (TUNEL assay) and likewise a significant reduction of formazan production (WST-1 test) in three cell lines. CONCLUSIONS: We found overexpression of ΔNp63α with and without irradiation in three cell lines, and the knockdown of ΔNp63α led to increased apoptotic events and fewer viable cells. Thus, the overexpression of ΔNp63α might protect carcinoma cells against irradiation effects. CLINICAL RELEVANCE: The present work supports the hypothesis that protein 63 might serve as a negative predictor for irradiation response and survival in a clinical setting and may be a target for future therapeutic strategies.

A spectroscopic approach to monitor the cut processing in pulsed laser osteotomy.

During laser osteotomy surgery, plasma arises at the place of ablation. It was the aim of this study to explore whether a spectroscopic analysis of this plasma would allow identification of the type of tissue that was affected by the laser. In an experimental setup (Rofin SCx10, CO(2) Slab Laser, wavelength 10.6 µm, pulse duration 80 µs, pulse repetition rate 200 Hz, max. output in cw-mode 100 W), the plasma spectra evoked by a pulsed laser, cutting 1-day postmortem pig and cow bones, were recorded. Spectra were compared to the reference spectrum of bone via correlation analysis. Our measurements show a clear differentiation between the plasma spectra when cutting either a bone or a soft tissue. The spectral changes could be detected from one to the next spectrum within 200 ms. Continuous surveillance of plasma spectra allows us to differentiate whether bone or soft tissue is hit by the last laser pulse. With this information, it may be possible to stop the laser when cutting undesired soft tissue and to design an automatic control of the ablation process.

Preoperative diagnostic for palatal implants: Is CT or CBCT necessary?

OBJECTIVE: To evaluate (a) the diagnostic value of lateral radiographs and (b) whether computed tomography (CT) or cone beam computed tomography (CBCT) is necessary in preoperative diagnostics for orthodontic anchorage implants. PATIENTS AND METHODS: We reviewed all patients who had presented for insertion of a palatal implant between January 2003 and December 2007 at the University Hospital Mainz. On the basis of lateral radiographs, the palatal bone was assessed as follows: (a) sufficient (bone height > 4 mm in the implant axis), (b) ambiguous, or (c) insufficient (bone height < 4 mm in the implant axis). In group A the surgical insertion procedure was performed without further radiological investigation. Group C required other types of anchorage. In cases of an ambiguous bone situation (group B), further diagnostic procedures (CT/CBCT) were performed. RESULTS: During the observation period, 105 patients were screened. Fourteen patients opted for alternative treatment leaving 91 patients for final evaluation. In 89 patients (97.8%), the lateral radiographs showed sufficient bone in the vertical dimension. In all of these cases, the availability of sufficient bone was confirmed intraoperatively. Further investigations were performed in two patients (2.2%) of group B (one CT, one CBCT). Finally, one patient had insufficient bone whereas the second had sufficient bone. CONCLUSIONS: Nearly 98% of the patients included in this study had sufficient bone for palatal implant insertion. Lateral radiographs permit correct and reliable evaluation of the quantity of bone in preoperative diagnosis of palatal implants. Additional imaging (CT or CBCT) is only required in rare cases of borderline dimensions.

Prognostic parameters contributing to palatal implant failures: a long-term survival analysis of 239 patients.

OBJECTIVE: To evaluate the demographic, radiological and therapeutic parameters that influence the overall clinical performance of palatal implants subjected to orthodontic loading. PATIENTS AND METHODS: The data of all patients who had received an orthodontic palatal implant for skeletal anchorage between January 1998 and December 2007 were reviewed retrospectively. The primary endpoint was the implant loss. The following parameters were assessed by univariate (log-rank test) and multivariate (Cox's regression) analysis: (a) age and gender, (b) vertical bone height along the prospective implant axis, (c) surgeon's experience and (d) implant type. RESULTS: Two-hundred and thirty-nine palatal implants were inserted in patients aged between 10 and 65 years. In all, 11/239 (4.6%) implants were lost: nine during the healing phase and two under functional loading. On univariate analysis, "surgeon's experience" was associated with a better implant survival and vice versa (P=0.0005; log-rank test). The significance of "surgeon's experience" was confirmed by Cox's regression analysis (P=0.001; Wald test). All other parameters had no impact on implant loss. CONCLUSIONS: The survival probability of palatal implants is not related to demographic and radiological parameters. Implant losses mainly occurred early in the healing phase of the palatal implant. According to our data, "surgeon's experience" is the cornerstone of palatal implant success.