Pulpal response following anterior maxillary osteotomy

The Incidence of Devitalization of Vital Teeth Associated with Pathologies of the Jaws Following Surgical Intervention: A Mixed-case Study

AIM

The purpose of this mixed-case study is to explore the incidence of pulp necrosis of vital teeth after surgical treatment of adjacent lesions of the jaws.

MATERIALS AND METHODS

The records of 341 biopsies submitted to the institute's histopathology laboratory were reviewed to include cases that met the inclusion criteria. About 84 biopsies collected from patients during surgical enucleation of lesions in proximity to healthy vital teeth were included of which 22 patients were recalled. Adjacent teeth were examined clinically and radiographically to assess their pulpal and periapical status after at least 8 months of follow-up.

RESULTS

There were 7 different pathological lesions diagnosed histologically. The follow-up period ranged between 8 and 72 months; 12 cases (54.6%) have developed pulpal necrosis for at least one tooth after surgical enucleation of the lesion. The other 10 cases (45.4%) showed normal responses to sensibility testing for all the teeth adjacent to the lesion. Ten out of the 12 cases (83%) that underwent pulpal necrosis were associated with odontogenic cysts, whereas the remaining 2 were associated with periapical granuloma and fibrous dysplasia.

CONCLUSION

Pulp necrosis is high in vital teeth associated with lesions without pulpal involvement. These teeth may benefit from root canal treatment prior to surgical enucleation of the lesion, which may prevent impaired healing or recurrence of infection.

CLINICAL SIGNIFICANCE

Careful treatment planning and thorough discussion should take place between the surgeons, endodontists, and patients prior to executing the treatment. The patient should be aware that there is a possibility that they may need root canal treatment as a preventative measure to enhance the chances of healing following the surgical procedures and in case the patients opted not to perform root canal treatment beforehand, close follow-up in the future should take place to monitor the vitality of the teeth in the follow-up visits.

Loss of pulp vitality after maxillary sinus augmentation: a surgical and endodontic approach

BACKGROUND

Maxillary sinus augmentation is a routine procedure performed in implant dentistry in cases with sinus pneumatization. This study presents a series of clinical cases in which tooth devitalization occurred in conjunction with sinus augmentation.

METHODS

In the three cases presented, a sinus-lift procedure was performed that resulted in devitalization of the adjacent teeth. Patients were referred to an endodontist for evaluation and treatment. Vitality of the teeth was determined by the use of a cold test, electric pulp test, and cavity test. The pulp was considered to be necrotic if the tests were negative.

RESULTS

In this case series, loss of pulp vitality of two maxillary left second premolars and one maxillary left first molar occurs after sinus-augmentation procedures. The devitalized teeth were free of caries. In one case, two amalgam restorations were present.

CONCLUSION

Pulp necrosis may occur in conjunction with a sinus-lift procedure in cases when an adjacent root is in close proximity to the sinus floor and the sinus membrane is elevated over the root apex.

The influence of expansion on intraoperative bone blood flow in multisegmental maxillary osteotomies: an experimental study

The aim of the presented study was to investigate the effect of maxillary expansion in multisegmental Le Fort I osteotomies on bone blood flow. Five sheep underwent a three-piece total maxillary osteotomy. Bone blood flow was measured intraoperatively by laser Doppler flowmetry in the premaxilla, the lateral segments and the mandible before osteotomy, after osteotomy and segmentation as well as after 4mm, 8mm and 12mm expansion with a Hyrax screw. A significant reduction in blood flow was seen after osteotomy and segmentation with a factor of 3.10 and between 4mm and 8mm expansion with a factor of 1.81. No significant differences could be found between 0mm and 4mm widening or between 8mm and 12mm widening. These results suggest that expansion of more than 4mm in multisegmental osteotomies enhances the risk of avascular sequelae. As greater maxillary widening has been carried out in many cases without avascular complications, further research on additional factors, influencing the recovery of perfusion, is needed.

Effect of segmental Le Fort I osteotomy on maxillary tooth type-related pulpal blood-flow characteristics

Laser Doppler flowmetry (LDF) is a noninvasive method to assess pulpal blood-flow (PBF). Osteotomies may have segment-related losses of pulpal sensibility.

OBJECTIVES

To determine the effect of segmental Le Fort I osteotomy on tooth-type related PBF values.

MATERIALS AND METHODS

In 12 volunteers, maxillary incisors, canines, and premolars were investigated bilaterally by LDF to assess local PBF values before and after surgery. Perfusion units (PU) were in 3 sessions, on the day before surgery and at 4 and 56 days after osteotomy.

RESULTS

Measurements before surgery were significantly higher than at 4 days after surgery for the canine (P <.01) and for the overall PBF values (P <.01). At 4 days assessment, PBF values of tooth types adjacent to vertical osteotomy cuts showed a significant decrease for the lateral incisors (P <.05), canines, and first premolars (P <.05), with no significant differences between the preoperative and postoperative values for tooth types not adjacent to vertical osteotomy cuts (P <.05).

CONCLUSIONS

Segmental Le Fort I osteotomy induced a short-term and long-term decrease in maxillary PBF values of tooth types adjacent to vertical osteotomy cuts.

Multiple-segment osteotomy in maxillofacial surgery

Multiple-segment osteotomy is defined as an osteotomy that divides the tooth-bearing arch of the maxilla or mandible into three or more segments. Combining large-segment orthognathic surgery and unitooth or small-segment surgery is an effective approach for dealing with a wide range of dentofacial deformities with occlusal problems. The indications for a multiple-segment osteotomy included dentofacial deformities and malocclusions requiring stable correction within a short overall treatment period. From 1991 to 1997, a total of 85 patients had multiple-segment osteotomy orthognathic procedures performed at Chang Gung Memorial Hospital. The indications for surgery were maxillary protrusion/deformity (31 patients), mandibular prognathism (51 patients), and noncleft maxillary retrusion (three patients). The types of osteotomies performed were Le Fort I, anterior segmental osteotomies of the maxilla or the mandible, palatal split, posterior segment, and unitooth or double-tooth segments. Follow-up ranged from 6 months to 7 years; stability was seen in movements, with only three complications (one partial gingival loss and two inferior mental paresthesias). No osteotomized segments were lost. The average overall treatment time was approximately 15 months, including 3 to 6 months of preoperative and 9 to 12 months of postoperative orthodontic treatment. This is at least 6 months shorter than traditional orthognathic surgery. Experience with 85 consecutive patients has shown that the results are good and the procedure is safe, with minimal complications.

Periodontal and pulpal condition of the central incisors after midline osteotomy of the maxilla

PURPOSE

The purpose of this study was to evaluate the periodontal and pulpal condition of the central incisors after Le Fort I and midline osteotomies for transverse expansion of the maxilla.

PATIENTS AND METHODS

The series included 12 women and eight men, with an average age at operation of 28.4 years (range, 17 to 48 years). Each patient, examined retrospectively, underwent transverse expansion of the maxilla by combined Le Fort I and midline osteotomies. The minimum follow-up was 12 months (range, 12 to 85 months, with an average of 38 months). The central incisors were tested for percussion sound, mobility, and pulpal response to electric stimulation, and then compared with the lateral incisors. The pocket depths and the height of the alveolar bone were measured, and the root surface was evaluated for resorption on radiographs.

RESULTS

Percussion and mobility tests indicated normal values for all teeth. Four (11%) of the central incisors did not respond to electrical stimulation. There was no difference in pocket depth between the mesial and distal sulci of the central incisors. In one tooth, resorption was detectable on the medial surface of the root. Minor root surface injury was seen in two roots, although these injuries were not progressive. The alveolar bone level of the central incisors was located slightly more superiorly on the mesial than on the distal side.

CONCLUSIONS

Although there may be some minor complications to the periodontal and pulpal tissues after combined Le Fort I and midline osteotomies, the harmful effects seem to be of negligible clinical significance.

Long-term histologic changes in the dental pulp after posterior segmental osteotomies

OBJECTIVE

The purpose of this study was to examine pulp tissue for 18 months after segmental osteotomy in nonhuman primates.

STUDY DESIGN

In this long-term experimental study, subapical, posterior, maxillary, and mandibular osteotomies were done in 26 baboons (Papio ursinus). Baboons were killed humanely immediately after operation and at 3, 6, 12, and 18 months, when tissues were perfusion-fixed. Longitudinal step-serial sections of dental pulps were examined.

RESULTS

There was a loss of the odontoblast layer as early as 3 months after surgery. Inflammatory cell infiltrate was most marked in the early postoperative stages, and the formation of osteodentin and secondary dentin was evident after 6 months. Foci of necrosis were present in the 3-month and 6-month groups but were replaced by pulp fibrosis in the 12-month and 18-month groups. All these changes were more frequent in experimental than control teeth.

CONCLUSIONS

The histologic changes seen should not affect the prognosis of teeth in subapical osteotomy segments if clinicians are careful not to damage root apices and do regular, careful, clinical, and radiographic follow-up examinations. Because many pulps healed spontaneously in the study teeth, endodontic treatment should be delayed until it is clearly needed.

Laser Doppler flowmetry in the assessment of tooth vitality after Le Fort I osteotomy

The aim of the present study was to evaluate pulp vitality in 15 patients, 11 to 29 months after a Le Fort I osteotomy. Assessment of pulpal blood flow was obtained by means of laser Doppler flowmetry, and it was measured bilaterally from the first maxillary premolar to the central incisor. The results were compared with those obtained by electric pulp testing in the same teeth. In addition, periodontal ligament perception was evaluated by applying axial loads to the central incisors. Radiographs were also studied. Fourteen subjects served as a control group. There was no significant difference between the level of pulpal blood flow in the teeth of the operated group compared with the control group. Twenty-one per cent of the teeth in the group operated on were insensitive to electric pulp testing, and in the remaining 79% the mean threshold was significantly higher than in the corresponding teeth in the control subjects. Similarly, the axial load threshold for the incisors for the control subjects was below 5 g, but in the group operated on 66% had a threshold above 5 g. These experiments clearly demonstrate that teeth without normal innervation can have an intact blood supply and be vital.

Pulpal and apical changes secondary to segmental osteotomy in the mandible--an experimental study

Posterior segmental osteotomies were performed on 7 dogs to investigate postoperative changes in the pulpal and periodontal tissue. Osteotomy cuts were made at various distances from the apices of roots. After 3 to 6 months, results were evaluated clinically, radiographically and histopathologically. Clinical and radiographic healing of the osteotomy sites was uneventful. Histological evaluation revealed that when the osteotomy cuts were made at a safe distance (3-5 mm) from the apices of roots, neither important pulpal degeneration nor loss of teeth occurred. Even two of the teeth whose apices were cut off had completely healthy pulpal and periapical tissues. The periodontium in almost all of the cases was also found to be healthy.

Pulpal and radicular changes following maxillary subapical corticotomy

Pulpal and radicular changes after subapical corticotomy in combination with posterior transfer of the maxilla were studied histopathologically using monkey jaws. When the surgical procedures were successful, the pulp tissues were kept alive, even though some slight atrophy and degeneration appeared. In some cases, however, severe reticular atrophy occurred which might be due to anaemia during operations.

Aseptic necrosis following maxillary osteotomies: report of 36 cases

The sequelae of insufficient vascularity following maxillary orthognathic surgery can vary from loss of tooth vitality, to periodontal defects, to tooth loss, to loss of major maxillary dentoalveolar segments. The results of a questionnaire mailed to oral and maxillofacial surgeons found this complication was most likely to occur with Le Fort I osteotomies done in multiple segments in conjunction with superior repositioning and transverse expansion. Significant palatal perforations definitely seem to compromise the already tenuous blood supply to the anterior maxilla. Suggestions are given regarding the prevention and treatment of this complication.

Tooth pulp changes following Le Fort I maxillary osteotomy in a primate model

Le Fort I maxillary 'down-fracture' osteotomy with 8 mm advancement was performed in 15 adult rhesus monkeys. Forty-five tooth pulps were examined histologically at intervals from 0 to 24 weeks after surgery. Cell degeneration occurred in 31% of pulps examined, necrosis in 16% of pulps and osteo-dentine was found in 7% of pulps. Almost half of the teeth examined (47%) showed marked cellular changes, more frequently found in posterior teeth. Other features noted were inflammation (13%) and reactive dentine in pulps (24%). Axons degenerated initially but recovered by 24 weeks. It is concluded that Le Fort I maxillary osteotomy caused pulpal disturbances in an animal model and the extent to which this occurs in patients needs to be carefully monitored.

Relationship of mandibular anterior tooth apices to genial muscle attachments

Ten adult midsagittally sectioned cadaver heads were used to measure the distance between the apex of the central incisor or canine teeth and the attachment of the genioglossus or geniohyoid muscles. Measurements were made on both cadaver specimens and radiographs. The results of the two methods showed no statistically significant difference. The results indicate that there is a relatively small chance (5.6%) of including the genioglossus attachment in the lingual pedicle if an anterior mandibular subapical osteotomy is positioned 3 to 5 mm below the incisor apex but a large chance (65%) of including the genioglossus muscle when the osteotomy procedure includes the canine teeth.

Long-term evaluation of human teeth after Le Fort I osteotomy: a histologic and developmental study

Transient pulpal vascular ischemia and direct injury to the apices of the teeth have been implicated as the causes of degenerative and atrophic pulpal changes in experimental animals after Le Fort I osteotomy despite the presence of collateral circulation. The long-term clinical effect of these pathologic changes in human teeth has not been studied. Seventeen maxillary third molar teeth from 10 patients whose postsurgical follow-up ranged from 6 months to 78 months (mean, 40 months) were extracted. The long-term biologic effects of Le Fort I osteotomy on the pulp and on the development of teeth were retrospectively evaluated with clinical and standard histologic techniques. Normal teeth from patients who were not operated on were used as controls. Histologic examination revealed an intact pulpal circulation and minimal pathologic changes in the pulpal tissue. Clinical and radiographic studies showed that the growing teeth developed normally after surgery. The Le Fort I downfracture procedure had little discernible long-term effect on the pulp and on the development of human third molar teeth.

Recovery of maxillary sinus and tooth sensibility after le Fort I osteotomy

The post-operative effects of maxillary le Fort I osteotomies on tooth sensibility and recovery of maxillary sinus integrity has been studied in thirty patients. The results show that tooth sensibility is lost in over 90% of the teeth post-operatively but gradually returns by 18 months in almost all of the teeth. Radiographic examination of the maxillary sinus post-operatively shows total or almost total radiopacity in all patients whereas later controls at 2 months and 6 months show normalisation of the bony and soft tissue structures in over 55% of the patients. At 6 months some of the patients (30%) show latent mucosal borderline swelling either bilateral or unilateral. A certain remodelling of the maxillary sinus was seen in all patients.

Wound healing after anterior and posterior subapical osteotomy

Changes in the process of wound healing and in the dental pulp were examined following anterior and posterior mandibular subapical osteotomies in pig-tailed macaque monkeys. Results of microangiographic and histologic investigations indicated that degenerative pulpal changes may occur following mobilization and repositioning of small dentoalveolar segments. The potential significance of such degenerative pulpal changes and the need for routine dental radiographic checkups following anterior and posterior mandibular dentoalveolar surgery are discussed.

Studies on protracted tissue reactions and repair after circulatory and skeletal damage to the rat mandible

The effect of circulatory and skeletal damage to the distal part of the mandible was studied on young growing rats after interruption of the inferior alveolar artery. The central part of the mandible including the incisor was most vulnerable to circulatory trauma. Maximal damage was seen when the inferior alveolar artery was interrupted combined with bilateral reflection of the mandibular periosteum. The damage produced then was a necrosis of the incisor pulp, odontoblasts and enamel organ and extensive resorption of the centrally-located compact bone. When both sides of the mucoperiosteum remained intact, damage to the main vessels of the mandible did not produce total necrosis of the incisor pulp. Reparative events with production of a fibrous connective tissue of the pulp and osteodentin production were seen. After resorption of sequestered bone was finished, this was replaced by a cell-rich type of bone which also replaced the alveola of those animals which had had their incisors excised. Hypercementosis was seen in the molars after 1 year. No respiratory activity in the incisor pulps was seen after the circulatory damage.

Primate models in surgical orthodontics

Between 1969 and 1980, 22 studies using nonhuman primates for experimental research in surgical orthodontics were published in the American Journal of Orthodontics, Angle Orthodontist, Journal of Oral Surgery, or International Journal of Oral Surgery. The most common species used was the rhesus monkey, Macaca mulatta. As laboratory animals, monkeys are relatively expensive and difficult to obtain. These problems have limited the design of experimental studies. Sample sizes are often too small for statistical analysis, control groups are small or omitted, and it has frequently been necessary to pool animals of different ages and sexes. These compromises might be appropriate if monkeys are the best available experimental model for humans, but there is little evidence that this is the case. Monkeys do not fill the usual role of good experimental models, which is to simplify a complex system. The monkeys used for craniofacial surgery have normal craniofacial function and morphology for their species, unlike human clinical patients. Cephalometric radiographs and skull measurements taken on monkeys of the five most common experimental species indicate that all experimental animals are much more prognathic than humans, and sex differences in prognathism are small. However, because many species have a large sex difference in canine size, females are a better experimental model than males for some questions. Considering recent federal legislative interest in animal research and the decreasing financial support for research, it is essential that the choice of experimental animals be justifiable and cost-effective. It would be worthwhile to consider alternatives to primates as the species of choice for experimental research in surgical orthodontics.

Quantitative assessment of intrapulpal axon response to orthodontic movement

Nerve fiber changes are of potential concern during tooth movement. Quantitative and qualitative assessments using electron microscopy of nerve fibers entering the tooth give an indication of change in the remainder of the pulp. Eight healthy mandibular first premolars were selected from four subjects, so that respective pairs had open apices and short-term movement, open apices and long-term movement, closed apices and short-term movement, and closed apices and long-term movement. These were compared to forty-nine untreated control teeth. No significant differences in myelinated or unmyelinated axon number were observed between experimental and control teeth. Altered myelin figures, possibly degenerating, were observed in only a small percentage of axons in teeth moved for a short period. No alterations were observed in teeth moved for long periods. It is concluded that intrapulpal axon alterations are minimal and not progressive with conservative orthodontic tooth movement.

Early tissue reactions after circulatory and skeletal damage to the mandible of the rat

Skeletal and circulatory damage in the form of a fracture of the mandible, proximal to the entry of the inferior alveolar artery and other perforantes, alone or combined with unilateral or bilateral mucoperiosteal extirpation, was inflicted on growing young rats. A morphological study of the tissue changes in the bone, dental tissues and soft tissues was performed. Cutting of the nutrient vessels together with extirpation of the periosteum was followed after 10 days by extensive infarction of the incisor pulp, the odontoblasts and the apical part of the enamel organ. The bone was damaged centrally in the mandibular corpus and at the lower border of the ramus, and was partly resorbed during the experimental period. The periodontium showed dilated vessels, but was not damaged. The pulps of the three molars showed numerous dilated vessels but were otherwise not damaged. The oral mucosa, bone marrow, peripheral nerve tissue and peripherally situated bone were not altered. In the animals after fracture alone, oedema of the incisor pulp was present, but infarction did not occur with certainty. A similar bone damage as with mucoperiosteal extirpation was present. The incisor with its dentin and enamel-forming cells was most sensitive to circulatory disturbances due to its central location, while the gingivoperiodontal, mucoperiosteal and midline circulatory systems could nourish the peripheral parts of the mandible. The dependence of the different nutrient systems to bone and dental tissues is discussed.

Modification of the muco-periosteal flap design in anterior maxillary osteotomies

A modification of the mucoperiosteal flap planning for anterior maxillary osteotomy operations is suggested. This approach involves a total reflection of the labial mucoperiosteal flap, with the advantages of direct vision of the operative field thus providing easy and precise execution of the operative bony cuts, avoiding damage to the adjacent teeth and reduction of operating time. Sufficient blood supply to the mobilised segment is maintained through the palatal blood vessels. Corrective periodontal surgery may also be carried out at the same time.

Pulp changes after anterior mandibular subapical osteotomy in a primate model

Subapical osteotomy of the anterior mandible was carried out on 10 adult Macaca Irus monkeys with and without open bite. Teeth were extracted at 8 weeks, 12 weeks, 24 weeks and 1 year after surgery and the pulps examined histologically. No normal pulps were found. Progressive fibrosis and calcification was noted in all teeth. Patent pulp blood vessels were found up to 24 weeks after surgery. Pulp damage to teeth distal to the osteotomy site was found in 50% of cases. Control teeth extracted from the opposing jaw at the same intervals were all found to have normal pulps.

The early effects of segmental surgery on the human pulp

The teeth of two patients requiring preprosthetic segmental surgery were removed between 4 and 10 weeks postoperatively. The pulps of these teeth were examined histologically using sound teeth from patients of the same age as controls and it was generally found that the teeth from the repositioned segment retained their vitality; there was progressive degeneration of nerves except for the nonmyelinated nerves of the autonomac nervous system, which remained intact.

A longitudinal study on electrical pulp testing following Le Fort type osteotomy and Le Fort type fracture

A longitudinal study of electrical pulp testing was carried out in 27 cases, or 53 maxillary halves following Le Fort type fractures and Le Fort type osteotomies. On the average, most teeth required positive responses around 7 months or around 11 months afterwards. The central and lateral incisor teeth demonstrated poor results; only 8 percent and 36 percent responded positively at 8 months, and at 14 months, 23 per cent and 50 per cent, respectively. The overall percentage of responsive teeth was 29 percent at 6 months and 85 percent at 14 months. These results are discussed and compared with those of segmental maxillary osteotomy, together with the value of pulp testing in the diagnosis in fracture and osteotomy.